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408323581b
87 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
408323581b |
- Add support for running the kernel in a SEV-SNP guest, over a Secure
VM Service Module (SVSM).
When running over a SVSM, different services can run at different
protection levels, apart from the guest OS but still within the
secure SNP environment. They can provide services to the guest, like
a vTPM, for example.
This series adds the required facilities to interface with such a SVSM
module.
- The usual fixlets, refactoring and cleanups
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Merge tag 'x86_sev_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 SEV updates from Borislav Petkov:
- Add support for running the kernel in a SEV-SNP guest, over a Secure
VM Service Module (SVSM).
When running over a SVSM, different services can run at different
protection levels, apart from the guest OS but still within the
secure SNP environment. They can provide services to the guest, like
a vTPM, for example.
This series adds the required facilities to interface with such a
SVSM module.
- The usual fixlets, refactoring and cleanups
[ And as always: "SEV" is AMD's "Secure Encrypted Virtualization".
I can't be the only one who gets all the newer x86 TLA's confused,
can I?
- Linus ]
* tag 'x86_sev_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Documentation/ABI/configfs-tsm: Fix an unexpected indentation silly
x86/sev: Do RMP memory coverage check after max_pfn has been set
x86/sev: Move SEV compilation units
virt: sev-guest: Mark driver struct with __refdata to prevent section mismatch
x86/sev: Allow non-VMPL0 execution when an SVSM is present
x86/sev: Extend the config-fs attestation support for an SVSM
x86/sev: Take advantage of configfs visibility support in TSM
fs/configfs: Add a callback to determine attribute visibility
sev-guest: configfs-tsm: Allow the privlevel_floor attribute to be updated
virt: sev-guest: Choose the VMPCK key based on executing VMPL
x86/sev: Provide guest VMPL level to userspace
x86/sev: Provide SVSM discovery support
x86/sev: Use the SVSM to create a vCPU when not in VMPL0
x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0
x86/sev: Use kernel provided SVSM Calling Areas
x86/sev: Check for the presence of an SVSM in the SNP secrets page
x86/irqflags: Provide native versions of the local_irq_save()/restore()
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Borislav Petkov (AMD)
|
38918e0bb2 |
x86/sev: Move SEV compilation units
A long time ago it was agreed upon that the coco stuff needs to go where it belongs: https://lore.kernel.org/all/Yg5nh1RknPRwIrb8@zn.tnic and not keep it in arch/x86/kernel. TDX did that and SEV can't find time to do so. So lemme do it. If people have trouble converting their ongoing featuritis patches, ask me for a sed script. No functional changes. Move the instrumentation exclusion bits too, as helpfully caught and reported by the 0day folks. Closes: https://lore.kernel.org/oe-kbuild-all/202406220748.hG3qlmDx-lkp@intel.com Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-lkp/202407091342.46d7dbb-oliver.sang@intel.com Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Nikunj A Dadhania <nikunj@amd.com> Reviewed-by: Ashish Kalra <ashish.kalra@amd.com> Tested-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/r/20240619093014.17962-1-bp@kernel.org |
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Kirill A. Shutemov
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859e63b789 |
x86/tdx: Convert shared memory back to private on kexec
TDX guests allocate shared buffers to perform I/O. It is done by allocating pages normally from the buddy allocator and converting them to shared with set_memory_decrypted(). The second, kexec-ed kernel has no idea what memory is converted this way. It only sees E820_TYPE_RAM. Accessing shared memory via private mapping is fatal. It leads to unrecoverable TD exit. On kexec, walk direct mapping and convert all shared memory back to private. It makes all RAM private again and second kernel may use it normally. The conversion occurs in two steps: stopping new conversions and unsharing all memory. In the case of normal kexec, the stopping of conversions takes place while scheduling is still functioning. This allows for waiting until any ongoing conversions are finished. The second step is carried out when all CPUs except one are inactive and interrupts are disabled. This prevents any conflicts with code that may access shared memory. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Tested-by: Tao Liu <ltao@redhat.com> Link: https://lore.kernel.org/r/20240614095904.1345461-12-kirill.shutemov@linux.intel.com |
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Kirill A. Shutemov
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c3abbf1376 |
x86/tdx: Account shared memory
The kernel will convert all shared memory back to private during kexec. The direct mapping page tables will provide information on which memory is shared. It is extremely important to convert all shared memory. If a page is missed, it will cause the second kernel to crash when it accesses it. Keep track of the number of shared pages. This will allow for cross-checking against the shared information in the direct mapping and reporting if the shared bit is lost. Memory conversion is slow and does not happen often. Global atomic is not going to be a bottleneck. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Kai Huang <kai.huang@intel.com> Tested-by: Tao Liu <ltao@redhat.com> Link: https://lore.kernel.org/r/20240614095904.1345461-10-kirill.shutemov@linux.intel.com |
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Kirill A. Shutemov
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99c5c4c60e |
x86/mm: Make x86_platform.guest.enc_status_change_*() return an error
TDX is going to have more than one reason to fail enc_status_change_prepare(). Change the callback to return errno instead of assuming -EIO. Change enc_status_change_finish() too to keep the interface symmetric. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Tao Liu <ltao@redhat.com> Link: https://lore.kernel.org/r/20240614095904.1345461-8-kirill.shutemov@linux.intel.com |
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Kirill A. Shutemov
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66e48e491d |
cpu/hotplug, x86/acpi: Disable CPU offlining for ACPI MADT wakeup
ACPI MADT doesn't allow to offline a CPU after it has been woken up. Currently, CPU hotplug is prevented based on the confidential computing attribute which is set for Intel TDX. But TDX is not the only possible user of the wake up method. Any platform that uses ACPI MADT wakeup method cannot offline CPU. Disable CPU offlining on ACPI MADT wakeup enumeration. This has no visible effects for users: currently, TDX guest is the only platform that uses the ACPI MADT wakeup method. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Tao Liu <ltao@redhat.com> Link: https://lore.kernel.org/r/20240614095904.1345461-5-kirill.shutemov@linux.intel.com |
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Borislav Petkov (AMD)
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bc6f707fc0 |
x86/cc: Add cc_platform_set/_clear() helpers
Add functionality to set and/or clear different attributes of the
machine as a confidential computing platform. Add the first one too:
whether the machine is running as a host for SEV-SNP guests.
Fixes:
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Jason A. Donenfeld
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99485c4c02 |
x86/coco: Require seeding RNG with RDRAND on CoCo systems
There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND. If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical. So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot. Add this deliberately to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose. Any driver can call it with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never make it worse. Rather than trying to build something into the core of the RNG, consider the particular CoCo issue just a CoCo issue, and therefore separate it all out into driver (well, arch/platform) code. [ bp: Massage commit message. ] Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Elena Reshetova <elena.reshetova@intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240326160735.73531-1-Jason@zx2c4.com |
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Ard Biesheuvel
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1c811d403a |
x86/sev: Fix position dependent variable references in startup code
The early startup code executes from a 1:1 mapping of memory, which
differs from the mapping that the code was linked and/or relocated to
run at. The latter mapping is not active yet at this point, and so
symbol references that rely on it will fault.
Given that the core kernel is built without -fPIC, symbol references are
typically emitted as absolute, and so any such references occuring in
the early startup code will therefore crash the kernel.
While an attempt was made to work around this for the early SEV/SME
startup code, by forcing RIP-relative addressing for certain global
SEV/SME variables via inline assembly (see snp_cpuid_get_table() for
example), RIP-relative addressing must be pervasively enforced for
SEV/SME global variables when accessed prior to page table fixups.
__startup_64() already handles this issue for select non-SEV/SME global
variables using fixup_pointer(), which adjusts the pointer relative to a
`physaddr` argument. To avoid having to pass around this `physaddr`
argument across all functions needing to apply pointer fixups, introduce
a macro RIP_RELATIVE_REF() which generates a RIP-relative reference to
a given global variable. It is used where necessary to force
RIP-relative accesses to global variables.
For backporting purposes, this patch makes no attempt at cleaning up
other occurrences of this pattern, involving either inline asm or
fixup_pointer(). Those will be addressed later.
[ bp: Call it "rip_rel_ref" everywhere like other code shortens
"rIP-relative reference" and make the asm wrapper __always_inline. ]
Co-developed-by: Kevin Loughlin <kevinloughlin@google.com>
Signed-off-by: Kevin Loughlin <kevinloughlin@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/all/20240130220845.1978329-1-kevinloughlin@google.com
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Linus Torvalds
|
b4442cadca |
- Add support managing TDX host hardware
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Linus Torvalds
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b51cc5d028 |
x86/cleanups changes for v6.8:
- A micro-optimization got misplaced as a cleanup:
- Micro-optimize the asm code in secondary_startup_64_no_verify()
- Change global variables to local
- Add missing kernel-doc function parameter descriptions
- Remove unused parameter from a macro
- Remove obsolete Kconfig entry
- Fix comments
- Fix typos, mostly scripted, manually reviewed
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-cleanups-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Ingo Molnar:
- Change global variables to local
- Add missing kernel-doc function parameter descriptions
- Remove unused parameter from a macro
- Remove obsolete Kconfig entry
- Fix comments
- Fix typos, mostly scripted, manually reviewed
and a micro-optimization got misplaced as a cleanup:
- Micro-optimize the asm code in secondary_startup_64_no_verify()
* tag 'x86-cleanups-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
arch/x86: Fix typos
x86/head_64: Use TESTB instead of TESTL in secondary_startup_64_no_verify()
x86/docs: Remove reference to syscall trampoline in PTI
x86/Kconfig: Remove obsolete config X86_32_SMP
x86/io: Remove the unused 'bw' parameter from the BUILDIO() macro
x86/mtrr: Document missing function parameters in kernel-doc
x86/setup: Make relocated_ramdisk a local variable of relocate_initrd()
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Bjorn Helgaas
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54aa699e80 |
arch/x86: Fix typos
Fix typos, most reported by "codespell arch/x86". Only touches comments, no code changes. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20240103004011.1758650-1-helgaas@kernel.org |
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Kai Huang
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d623704bb2 |
x86/virt/tdx: Define TDX supported page sizes as macros
TDX supports 4K, 2M and 1G page sizes. The corresponding values are defined by the TDX module spec and used as TDX module ABI. Currently, they are used in try_accept_one() when the TDX guest tries to accept a page. However currently try_accept_one() uses hard-coded magic values. Define TDX supported page sizes as macros and get rid of the hard-coded values in try_accept_one(). TDX host support will need to use them too. Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/all/20231208170740.53979-2-dave.hansen%40intel.com |
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Kirill A. Shutemov
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f4116bfc44 |
x86/tdx: Allow 32-bit emulation by default
32-bit emulation was disabled on TDX to prevent a possible attack by a VMM injecting an interrupt on vector 0x80. Now that int80_emulation() has a check for external interrupts the limitation can be lifted. To distinguish software interrupts from external ones, int80_emulation() checks the APIC ISR bit relevant to the 0x80 vector. For software interrupts, this bit will be 0. On TDX, the VAPIC state (including ISR) is protected and cannot be manipulated by the VMM. The ISR bit is set by the microcode flow during the handling of posted interrupts. [ dhansen: more changelog tweaks ] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: <stable@vger.kernel.org> # v6.0+ |
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Kirill A. Shutemov
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b82a8dbd3d |
x86/coco: Disable 32-bit emulation by default on TDX and SEV
The INT 0x80 instruction is used for 32-bit x86 Linux syscalls. The
kernel expects to receive a software interrupt as a result of the INT
0x80 instruction. However, an external interrupt on the same vector
triggers the same handler.
The kernel interprets an external interrupt on vector 0x80 as a 32-bit
system call that came from userspace.
A VMM can inject external interrupts on any arbitrary vector at any
time. This remains true even for TDX and SEV guests where the VMM is
untrusted.
Put together, this allows an untrusted VMM to trigger int80 syscall
handling at any given point. The content of the guest register file at
that moment defines what syscall is triggered and its arguments. It
opens the guest OS to manipulation from the VMM side.
Disable 32-bit emulation by default for TDX and SEV. User can override
it with the ia32_emulation=y command line option.
[ dhansen: reword the changelog ]
Reported-by: Supraja Sridhara <supraja.sridhara@inf.ethz.ch>
Reported-by: Benedict Schlüter <benedict.schlueter@inf.ethz.ch>
Reported-by: Mark Kuhne <mark.kuhne@inf.ethz.ch>
Reported-by: Andrin Bertschi <andrin.bertschi@inf.ethz.ch>
Reported-by: Shweta Shinde <shweta.shinde@inf.ethz.ch>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@vger.kernel.org> # v6.0+:
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Linus Torvalds
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5e2cb28dd7 |
configfs-tsm for v6.7
- Introduce configfs-tsm as a shared ABI for confidential computing
attestation reports
- Convert sev-guest to additionally support configfs-tsm alongside its
vendor specific ioctl()
- Added signed attestation report retrieval to the tdx-guest driver
forgoing a new vendor specific ioctl()
- Misc. cleanups and a new __free() annotation for kvfree()
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Merge tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux
Pull unified attestation reporting from Dan Williams:
"In an ideal world there would be a cross-vendor standard attestation
report format for confidential guests along with a common device
definition to act as the transport.
In the real world the situation ended up with multiple platform
vendors inventing their own attestation report formats with the
SEV-SNP implementation being a first mover to define a custom
sev-guest character device and corresponding ioctl(). Later, this
configfs-tsm proposal intercepted an attempt to add a tdx-guest
character device and a corresponding new ioctl(). It also anticipated
ARM and RISC-V showing up with more chardevs and more ioctls().
The proposal takes for granted that Linux tolerates the vendor report
format differentiation until a standard arrives. From talking with
folks involved, it sounds like that standardization work is unlikely
to resolve anytime soon. It also takes the position that kernfs ABIs
are easier to maintain than ioctl(). The result is a shared configfs
mechanism to return per-vendor report-blobs with the option to later
support a standard when that arrives.
Part of the goal here also is to get the community into the
"uncomfortable, but beneficial to the long term maintainability of the
kernel" state of talking to each other about their differentiation and
opportunities to collaborate. Think of this like the device-driver
equivalent of the common memory-management infrastructure for
confidential-computing being built up in KVM.
As for establishing an "upstream path for cross-vendor
confidential-computing device driver infrastructure" this is something
I want to discuss at Plumbers. At present, the multiple vendor
proposals for assigning devices to confidential computing VMs likely
needs a new dedicated repository and maintainer team, but that is a
discussion for v6.8.
For now, Greg and Thomas have acked this approach and this is passing
is AMD, Intel, and Google tests.
Summary:
- Introduce configfs-tsm as a shared ABI for confidential computing
attestation reports
- Convert sev-guest to additionally support configfs-tsm alongside
its vendor specific ioctl()
- Added signed attestation report retrieval to the tdx-guest driver
forgoing a new vendor specific ioctl()
- Misc cleanups and a new __free() annotation for kvfree()"
* tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux:
virt: tdx-guest: Add Quote generation support using TSM_REPORTS
virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT
mm/slab: Add __free() support for kvfree
virt: sevguest: Prep for kernel internal get_ext_report()
configfs-tsm: Introduce a shared ABI for attestation reports
virt: coco: Add a coco/Makefile and coco/Kconfig
virt: sevguest: Fix passing a stack buffer as a scatterlist target
|
||
|
Linus Torvalds
|
8999ad99f4 |
* Refactor and clean up TDX hypercall/module call infrastructure
* Handle retrying/resuming page conversion hypercalls * Make sure to use the (shockingly) reliable TSC in TDX guests -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmVBlqMACgkQaDWVMHDJ krBrhBAArKay0MvzmdzS4IQs8JqkmuMEHI6WabYv2POPjJNXrn5MelLH972pLuX9 NJ3+yeOLmNMYwqu5qwLCxyeO5CtqEyT2lNumUrxAtHQG4+oS2RYJYUalxMuoGxt8 fAHxbItFg0TobBSUtwcnN2R2WdXwPuUW0Co+pJfLlZV4umVM7QANO1nf1g8YmlDD sVtpDaeKJRdylmwgWgAyGow0tDKd6oZB9j/vOHvZRrEQ+DMjEtG75fjwbjbu43Cl tI/fbxKjzAkOFcZ7PEPsQ8jE1h9DXU+JzTML9Nu/cPMalxMeBg3Dol/JOEbqgreI 4W8Lg7g071EkUcQDxpwfe4aS6rsfsbwUIV4gJVkg9ZhlT7RayWsFik2CfBpJ4IMQ TM8BxtCEGCz3cxVvg3mstX9rRA7eNlXOzcKE/8Y7cpSsp94bA9jtf2GgUSUoi9St y+fIEei8mgeHutdiFh8psrmR7hp6iX/ldMFqHtjNo6xatf2KjdVHhVSU13Jz544z 43ATNi1gZeHOgfwlAlIxLPDVDJidHuux3f6g2vfMkAqItyEqFauC1HA1pIDgckoY 9FpBPp9vNUToSPp6reB6z/PkEBIrG2XtQh82JLt2CnCb6aTUtnPds+psjtT4sSE/ a9SQvZLWWmpj+BlI2yrtfJzhy7SwhltgdjItQHidmCNEn0PYfTc= =FJ1Y -----END PGP SIGNATURE----- Merge tag 'x86_tdx_for_6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 TDX updates from Dave Hansen: "The majority of this is a rework of the assembly and C wrappers that are used to talk to the TDX module and VMM. This is a nice cleanup in general but is also clearing the way for using this code when Linux is the TDX VMM. There are also some tidbits to make TDX guests play nicer with Hyper-V and to take advantage the hardware TSC. Summary: - Refactor and clean up TDX hypercall/module call infrastructure - Handle retrying/resuming page conversion hypercalls - Make sure to use the (shockingly) reliable TSC in TDX guests" [ TLA reminder: TDX is "Trust Domain Extensions", Intel's guest VM confidentiality technology ] * tag 'x86_tdx_for_6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/tdx: Mark TSC reliable x86/tdx: Fix __noreturn build warning around __tdx_hypercall_failed() x86/virt/tdx: Make TDX_MODULE_CALL handle SEAMCALL #UD and #GP x86/virt/tdx: Wire up basic SEAMCALL functions x86/tdx: Remove 'struct tdx_hypercall_args' x86/tdx: Reimplement __tdx_hypercall() using TDX_MODULE_CALL asm x86/tdx: Make TDX_HYPERCALL asm similar to TDX_MODULE_CALL x86/tdx: Extend TDX_MODULE_CALL to support more TDCALL/SEAMCALL leafs x86/tdx: Pass TDCALL/SEAMCALL input/output registers via a structure x86/tdx: Rename __tdx_module_call() to __tdcall() x86/tdx: Make macros of TDCALLs consistent with the spec x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro x86/tdx: Retry partially-completed page conversion hypercalls |
||
Kuppuswamy Sathyanarayanan
|
f4738f56d1 |
virt: tdx-guest: Add Quote generation support using TSM_REPORTS
In TDX guest, the attestation process is used to verify the TDX guest trustworthiness to other entities before provisioning secrets to the guest. The first step in the attestation process is TDREPORT generation, which involves getting the guest measurement data in the format of TDREPORT, which is further used to validate the authenticity of the TDX guest. TDREPORT by design is integrity-protected and can only be verified on the local machine. To support remote verification of the TDREPORT in a SGX-based attestation, the TDREPORT needs to be sent to the SGX Quoting Enclave (QE) to convert it to a remotely verifiable Quote. SGX QE by design can only run outside of the TDX guest (i.e. in a host process or in a normal VM) and guest can use communication channels like vsock or TCP/IP to send the TDREPORT to the QE. But for security concerns, the TDX guest may not support these communication channels. To handle such cases, TDX defines a GetQuote hypercall which can be used by the guest to request the host VMM to communicate with the SGX QE. More details about GetQuote hypercall can be found in TDX Guest-Host Communication Interface (GHCI) for Intel TDX 1.0, section titled "TDG.VP.VMCALL<GetQuote>". Trusted Security Module (TSM) [1] exposes a common ABI for Confidential Computing Guest platforms to get the measurement data via ConfigFS. Extend the TSM framework and add support to allow an attestation agent to get the TDX Quote data (included usage example below). report=/sys/kernel/config/tsm/report/report0 mkdir $report dd if=/dev/urandom bs=64 count=1 > $report/inblob hexdump -C $report/outblob rmdir $report GetQuote TDVMCALL requires TD guest pass a 4K aligned shared buffer with TDREPORT data as input, which is further used by the VMM to copy the TD Quote result after successful Quote generation. To create the shared buffer, allocate a large enough memory and mark it shared using set_memory_decrypted() in tdx_guest_init(). This buffer will be re-used for GetQuote requests in the TDX TSM handler. Although this method reserves a fixed chunk of memory for GetQuote requests, such one time allocation can help avoid memory fragmentation related allocation failures later in the uptime of the guest. Since the Quote generation process is not time-critical or frequently used, the current version uses a polling model for Quote requests and it also does not support parallel GetQuote requests. Link: https://lore.kernel.org/lkml/169342399185.3934343.3035845348326944519.stgit@dwillia2-xfh.jf.intel.com/ [1] Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Reviewed-by: Erdem Aktas <erdemaktas@google.com> Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Tested-by: Peter Gonda <pgonda@google.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> |
||
|
Kirill A. Shutemov
|
9ee4318c15 |
x86/tdx: Mark TSC reliable
In x86 virtualization environments, including TDX, RDTSC instruction is
handled without causing a VM exit, resulting in minimal overhead and
jitters. On the other hand, other clock sources (such as HPET, ACPI
timer, APIC, etc.) necessitate VM exits to implement, resulting in more
fluctuating measurements compared to TSC. Thus, those clock sources are
not effective for calibrating TSC.
As a foundation, the host TSC is guaranteed to be invariant on any
system which enumerates TDX support.
TDX guests and the TDX module build on that foundation by enforcing:
- Virtual TSC is monotonously incrementing for any single VCPU;
- Virtual TSC values are consistent among all the TD’s VCPUs at the
level supported by the CPU:
+ VMM is required to set the same TSC_ADJUST;
+ VMM must not modify from initial value of TSC_ADJUST before
SEAMCALL;
- The frequency is determined by TD configuration:
+ Virtual TSC frequency is specified by VMM on TDH.MNG.INIT;
+ Virtual TSC starts counting from 0 at TDH.MNG.INIT;
The result is that a reliable TSC is a TDX architectural guarantee.
Use the TSC as the only reliable clock source in TD guests, bypassing
unstable calibration.
This is similar to what the kernel already does in some VMWare and
HyperV environments.
[ dhansen: changelog tweaks ]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Erdem Aktas <erdemaktas@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20231006144549.2633-1-kirill.shutemov%40linux.intel.com
|
||
Justin Stitt
|
c9babd5d95 |
x86/tdx: Replace deprecated strncpy() with strtomem_pad()
strncpy() works perfectly here in all cases, however, it is deprecated and
as such we should prefer more robust and less ambiguous string APIs:
https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Let's use strtomem_pad() as this matches the functionality of strncpy()
and is _not_ deprecated.
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://github.com/KSPP/linux/issues/90
Link: https://lore.kernel.org/r/20231003-strncpy-arch-x86-coco-tdx-tdx-c-v2-1-0bd21174a217@google.com
|
||
|
Kai Huang
|
8a8544bde8 |
x86/tdx: Remove 'struct tdx_hypercall_args'
Now 'struct tdx_hypercall_args' is basically 'struct tdx_module_args' minus RCX. Although from __tdx_hypercall()'s perspective RCX isn't used as shared register thus not part of input/output registers, it's not worth to have a separate structure just due to one register. Remove the 'struct tdx_hypercall_args' and use 'struct tdx_module_args' instead in __tdx_hypercall() related code. This also saves the memory copy between the two structures within __tdx_hypercall(). Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/798dad5ce24e9d745cf0e16825b75ccc433ad065.1692096753.git.kai.huang%40intel.com |
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Kai Huang
|
90f5ecd37f |
x86/tdx: Reimplement __tdx_hypercall() using TDX_MODULE_CALL asm
Now the TDX_HYPERCALL asm is basically identical to the TDX_MODULE_CALL with both '\saved' and '\ret' enabled, with two minor things though: 1) The way to restore the structure pointer is different The TDX_HYPERCALL uses RCX as spare to restore the structure pointer, but the TDX_MODULE_CALL assumes no spare register can be used. In other words, TDX_MODULE_CALL already covers what TDX_HYPERCALL does. 2) TDX_MODULE_CALL only clears shared registers for TDH.VP.ENTER For this just need to make that code available for the non-host case. Thus, remove the TDX_HYPERCALL and reimplement the __tdx_hypercall() using the TDX_MODULE_CALL. Extend the TDX_MODULE_CALL to cover "clear shared registers" for TDG.VP.VMCALL. Introduce a new __tdcall_saved_ret() to replace the temporary __tdcall_hypercall(). The __tdcall_saved_ret() can also be used for those new TDCALLs which require more input/output registers than the basic TDCALLs do. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/e68a2473fb6f5bcd78b078cae7510e9d0753b3df.1692096753.git.kai.huang%40intel.com |
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Kai Huang
|
c641cfb5c1 |
x86/tdx: Make TDX_HYPERCALL asm similar to TDX_MODULE_CALL
Now the 'struct tdx_hypercall_args' and 'struct tdx_module_args' are
almost the same, and the TDX_HYPERCALL and TDX_MODULE_CALL asm macro
share similar code pattern too. The __tdx_hypercall() and __tdcall()
should be unified to use the same assembly code.
As a preparation to unify them, simplify the TDX_HYPERCALL to make it
more like the TDX_MODULE_CALL.
The TDX_HYPERCALL takes the pointer of 'struct tdx_hypercall_args' as
function call argument, and does below extra things comparing to the
TDX_MODULE_CALL:
1) It sets RAX to 0 (TDG.VP.VMCALL leaf) internally;
2) It sets RCX to the (fixed) bitmap of shared registers internally;
3) It calls __tdx_hypercall_failed() internally (and panics) when the
TDCALL instruction itself fails;
4) After TDCALL, it moves R10 to RAX to return the return code of the
VMCALL leaf, regardless the '\ret' asm macro argument;
Firstly, change the TDX_HYPERCALL to take the same function call
arguments as the TDX_MODULE_CALL does: TDCALL leaf ID, and the pointer
to 'struct tdx_module_args'. Then 1) and 2) can be moved to the
caller:
- TDG.VP.VMCALL leaf ID can be passed via the function call argument;
- 'struct tdx_module_args' is 'struct tdx_hypercall_args' + RCX, thus
the bitmap of shared registers can be passed via RCX in the
structure.
Secondly, to move 3) and 4) out of assembly, make the TDX_HYPERCALL
always save output registers to the structure. The caller then can:
- Call __tdx_hypercall_failed() when TDX_HYPERCALL returns error;
- Return R10 in the structure as the return code of the VMCALL leaf;
With above changes, change the asm function from __tdx_hypercall() to
__tdcall_hypercall(), and reimplement __tdx_hypercall() as the C wrapper
of it. This avoids having to add another wrapper of __tdx_hypercall()
(_tdx_hypercall() is already taken).
The __tdcall_hypercall() will be replaced with a __tdcall() variant
using TDX_MODULE_CALL in a later commit as the final goal is to have one
assembly to handle both TDCALL and TDVMCALL.
Currently, the __tdx_hypercall() asm is in '.noinstr.text'. To keep
this unchanged, annotate __tdx_hypercall(), which is a C function now,
as 'noinstr'.
Remove the __tdx_hypercall_ret() as __tdx_hypercall() already does so.
Implement __tdx_hypercall() in tdx-shared.c so it can be shared with the
compressed code.
Opportunistically fix a checkpatch error complaining using space around
parenthesis '(' and ')' while moving the bitmap of shared registers to
<asm/shared/tdx.h>.
[ dhansen: quash new calls of __tdx_hypercall_ret() that showed up ]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/0cbf25e7aee3256288045023a31f65f0cef90af4.1692096753.git.kai.huang%40intel.com
|
||
|
Kai Huang
|
12f34ed862 |
x86/tdx: Extend TDX_MODULE_CALL to support more TDCALL/SEAMCALL leafs
The TDX guest live migration support (TDX 1.5) adds new TDCALL/SEAMCALL
leaf functions. Those new TDCALLs/SEAMCALLs take additional registers
for input (R10-R13) and output (R12-R13). TDG.SERVTD.RD is an example.
Also, the current TDX_MODULE_CALL doesn't aim to handle TDH.VP.ENTER
SEAMCALL, which monitors the TDG.VP.VMCALL in input/output registers
when it returns in case of VMCALL from TDX guest.
With those new TDCALLs/SEAMCALLs and the TDH.VP.ENTER covered, the
TDX_MODULE_CALL macro basically needs to handle the same input/output
registers as the TDX_HYPERCALL does. And as a result, they also share
similar logic in the assembly, thus should be unified to use one common
assembly.
Extend the TDX_MODULE_CALL asm to support the new TDCALLs/SEAMCALLs and
also the TDH.VP.ENTER SEAMCALL. Eventually it will be unified with the
TDX_HYPERCALL.
The new input/output registers fit with the "callee-saved" registers in
the x86 calling convention. Add a new "saved" parameter to support
those new TDCALLs/SEAMCALLs and TDH.VP.ENTER and keep the existing
TDCALLs/SEAMCALLs minimally impacted.
For TDH.VP.ENTER, after it returns the registers shared by the guest
contain guest's values. Explicitly clear them to prevent speculative
use of guest's values.
Note most TDX live migration related SEAMCALLs may also clobber AVX*
state ("AVX, AVX2 and AVX512 state: may be reset to the architectural
INIT state" -- see TDH.EXPORT.MEM for example). And TDH.VP.ENTER also
clobbers XMM0-XMM15 when the corresponding bit is set in RCX. Don't
handle them in the TDX_MODULE_CALL macro but let the caller save and
restore when needed.
This is basically based on Peter's code.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/d4785de7c392f7c5684407f6c24a73b92148ec49.1692096753.git.kai.huang%40intel.com
|
||
|
Kai Huang
|
57a420bb81 |
x86/tdx: Pass TDCALL/SEAMCALL input/output registers via a structure
Currently, the TDX_MODULE_CALL asm macro, which handles both TDCALL and SEAMCALL, takes one parameter for each input register and an optional 'struct tdx_module_output' (a collection of output registers) as output. This is different from the TDX_HYPERCALL macro which uses a single 'struct tdx_hypercall_args' to carry all input/output registers. The newer TDX versions introduce more TDCALLs/SEAMCALLs which use more input/output registers. Also, the TDH.VP.ENTER (which isn't covered by the current TDX_MODULE_CALL macro) basically can use all registers that the TDX_HYPERCALL does. The current TDX_MODULE_CALL macro isn't extendible to cover those cases. Similar to the TDX_HYPERCALL macro, simplify the TDX_MODULE_CALL macro to use a single structure 'struct tdx_module_args' to carry all the input/output registers. Currently, R10/R11 are only used as output register but not as input by any TDCALL/SEAMCALL. Change to also use R10/R11 as input register to make input/output registers symmetric. Currently, the TDX_MODULE_CALL macro depends on the caller to pass a non-NULL 'struct tdx_module_output' to get additional output registers. Similar to the TDX_HYPERCALL macro, change the TDX_MODULE_CALL macro to take a new 'ret' macro argument to indicate whether to save the output registers to the 'struct tdx_module_args'. Also introduce a new __tdcall_ret() for that purpose, similar to the __tdx_hypercall_ret(). Note the tdcall(), which is a wrapper of __tdcall(), is called by three callers: tdx_parse_tdinfo(), tdx_get_ve_info() and tdx_early_init(). The former two need the additional output but the last one doesn't. For simplicity, make tdcall() always call __tdcall_ret() to avoid another "_ret()" wrapper. The last caller tdx_early_init() isn't performance critical anyway. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/483616c1762d85eb3a3c3035a7de061cfacf2f14.1692096753.git.kai.huang%40intel.com |
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|
Kai Huang
|
5efb96289e |
x86/tdx: Rename __tdx_module_call() to __tdcall()
__tdx_module_call() is only used by the TDX guest to issue TDCALL to the TDX module. Rename it to __tdcall() to match its behaviour, e.g., it cannot be used to make host-side SEAMCALL. Also rename tdx_module_call() which is a wrapper of __tdx_module_call() to tdcall(). No functional change intended. Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/785d20d99fbcd0db8262c94da6423375422d8c75.1692096753.git.kai.huang%40intel.com |
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|
Kai Huang
|
f0024dbfc4 |
x86/tdx: Make macros of TDCALLs consistent with the spec
The TDX spec names all TDCALLs with prefix "TDG". Currently, the kernel doesn't follow such convention for the macros of those TDCALLs but uses prefix "TDX_" for all of them. Although it's arguable whether the TDX spec names those TDCALLs properly, it's better for the kernel to follow the spec when naming those macros. Change all macros of TDCALLs to make them consistent with the spec. As a bonus, they get distinguished easily from the host-side SEAMCALLs, which all have prefix "TDH". No functional change intended. Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/516dccd0bd8fb9a0b6af30d25bb2d971aa03d598.1692096753.git.kai.huang%40intel.com |
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|
Kai Huang
|
03a423d40c |
x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid
If SEAMCALL fails with VMFailInvalid, the SEAM software (e.g., the TDX module) won't have chance to set any output register. Skip saving the output registers to the structure in this case. Also, as '.Lno_output_struct' is the very last symbol before RET, rename it to '.Lout' to make it short. Opportunistically make the asm directives unindented. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/704088f5b4d72c7e24084f7f15bd1ac5005b7213.1692096753.git.kai.huang%40intel.com |
||
|
Kai Huang
|
5d092b6611 |
x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro
In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the untrusted VMM, the registers that the TDX guest shares to the VMM need to be cleared to avoid speculative execution of VMM-provided values. RSI is specified in the bitmap of those registers, but it is missing when zeroing out those registers in the current TDX_HYPERCALL. It was there when it was originally added in commit |
||
Dexuan Cui
|
019b383d11 |
x86/tdx: Retry partially-completed page conversion hypercalls
TDX guest memory is private by default and the VMM may not access it. However, in cases where the guest needs to share data with the VMM, the guest and the VMM can coordinate to make memory shared between them. The guest side of this protocol includes the "MapGPA" hypercall. This call takes a guest physical address range. The hypercall spec (aka. the GHCI) says that the MapGPA call is allowed to return partial progress in mapping this range and indicate that fact with a special error code. A guest that sees such partial progress is expected to retry the operation for the portion of the address range that was not completed. Hyper-V does this partial completion dance when set_memory_decrypted() is called to "decrypt" swiotlb bounce buffers that can be up to 1GB in size. It is evidently the only VMM that does this, which is why nobody noticed this until now. [ dhansen: rewrite changelog ] Signed-off-by: Dexuan Cui <decui@microsoft.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: https://lore.kernel.org/all/20230811021246.821-2-decui%40microsoft.com |
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|
Linus Torvalds
|
12dc010071 |
- Some SEV and CC platform helpers cleanup and simplifications now that
the usage patterns are becoming apparent -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmSa9CoACgkQEsHwGGHe VUr1NhAAjmOq/T41u3FCSU6fZ8gXo5UkIUT13a6cx+6Omx9waJn5G0xdf/380vQN RPRTcc4cfQHCdnIeHgiz1YtCh1ljxXswOSbexHgWHjEcqadgxkZTlKaBEbqyEwLI lnRRsowfk7J/8RsYqtzuBvGaWNliiszWE8iayruI1IL+FoEDLlLx1GNYqusP5WIs 0KYm919Zozl8FEZjP47nH4bab1RcE+HGmLG7UEBmR0zHl4cc7iN3wpv2o/vDxVzR /KP8a2G7J/xjllGW+OP81dFCS7iklHpNuaxQS73fDIL7ll2VDqNemh4ivykCrplo 93twODBwKboKmZhnKc0M2axm5JGGx7IC3KTqEUHzb2Wo4bZCYnrj+9Utzxsa3FxB m0BSUcmBqzZCsHCbu62N66l1NlB32EnMO80/45NrgGi62YiGP8qQNhy3TiceUNle NHFkQmRZwLyW5YC1ntSK8fwSu4GrMG1MG/eRfMPDmmsYogiZUm2KIj7XKy3dKXR6 maqifh/raPk3rL+7cl9BQleCDLjnkHNxFxFa329P9K4wrtqn7Ley4izWYAUYhNrl VOjLs+thTwEmPPgpo/K1wAbR/PjLdmSQ/fQR6w7eUrzNVnm5ndXzhTUcIawycG3T haVry+xPMIRlLCIg+dkrwwNcTW1y/X3K4SmgnjLLF57lZFn9UJc= =Aj6p -----END PGP SIGNATURE----- Merge tag 'x86_sev_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 SEV updates from Borislav Petkov: - Some SEV and CC platform helpers cleanup and simplifications now that the usage patterns are becoming apparent [ I'm sure I'm the only one that has gets confused by all the TLAs, but in case there are others: here SEV is AMD's "Secure Encrypted Virtualization" and CC is generic "Confidential Computing". There's also Intel SGX (Software Guard Extensions) and TDX (Trust Domain Extensions), along with all the vendor memory encryption extensions (SME, TSME, TME, and WTF). And then we have arm64 with RMA and CCA, and I probably forgot another dozen or so related acronyms - Linus ] * tag 'x86_sev_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/coco: Get rid of accessor functions x86/sev: Get rid of special sev_es_enable_key x86/coco: Mark cc_platform_has() and descendants noinstr |
||
|
Linus Torvalds
|
5dfe7a7e52 |
- Fix a race window where load_unaligned_zeropad() could cause
a fatal shutdown during TDX private<=>shared conversion
- Annotate sites where VM "exit reasons" are reused as hypercall
numbers.
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Merge tag 'x86_tdx_for_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 tdx updates from Dave Hansen:
- Fix a race window where load_unaligned_zeropad() could cause a fatal
shutdown during TDX private<=>shared conversion
The race has never been observed in practice but might allow
load_unaligned_zeropad() to catch a TDX page in the middle of its
conversion process which would lead to a fatal and unrecoverable
guest shutdown.
- Annotate sites where VM "exit reasons" are reused as hypercall
numbers.
* tag 'x86_tdx_for_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mm: Fix enc_status_change_finish_noop()
x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad()
x86/mm: Allow guest.enc_status_change_prepare() to fail
x86/tdx: Wrap exit reason with hcall_func()
|
||
|
Linus Torvalds
|
2c96136a3f |
- Add support for unaccepted memory as specified in the UEFI spec v2.9.
The gist of it all is that Intel TDX and AMD SEV-SNP confidential computing guests define the notion of accepting memory before using it and thus preventing a whole set of attacks against such guests like memory replay and the like. There are a couple of strategies of how memory should be accepted - the current implementation does an on-demand way of accepting. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmSZ0f4ACgkQEsHwGGHe VUpasw//RKoNW9HSU1csY+XnG9uuaT6QKgji+gIEZWWIGPO9iibvbBj6P5WxJE8T fe7yb6CGa6d6thoU0v+mQGVVvCd7OjCFwPD5wAo4mXToD7Ig+4mI6jMkaKifqa2f N1Uuy8u/zQnGyWrP5Y//WH5bJYfsmds4UGwXI2nLvKlhE7MG90/ePjt7iqnnwZsy waLp6a0Q1VeOvnfRszFLHZw/SoER5RSJ4qeVqttkFNmPPEKMK1Kirrl2poR56OQJ nMr6LqVtD7erlSJ36VRXOKzLI443A4iIEIg/wBjIOU6L5ZEWJGNqtCDnIqFJ6+TM XatsejfRYkkMZH0qXtX9+M0u+HJHbZPCH5rEcA21P3Nbd7od/ANq91qCGoMjtUZ4 7pZohMG8M6IDvkLiOb8fQVkR5k/9Jbk8UvdN/8jdPx1ERxYMFO3BDvJpV2gzrW4B KYtFTPR7j2nY3eKfDpe3flanqYzKUBsKoTlLnlH7UHaiMZ2idwG8AQjlrhC/erCq /Lq1LXt4Mq46FyHABc+PSHytu0WWj1nBUftRt+lviY/Uv7TlkBldOTT7wm7itsfF HUCTfLWl0CJXKPq8rbbZhAG/exN6Ay6MO3E3OcNq8A72E5y4cXenuG3ic/0tUuOu FfjpiMk35qE2Qb4hnj1YtF3XINtd1MpKcuwzGSzEdv9s3J7hrS0= =FS95 -----END PGP SIGNATURE----- Merge tag 'x86_cc_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 confidential computing update from Borislav Petkov: - Add support for unaccepted memory as specified in the UEFI spec v2.9. The gist of it all is that Intel TDX and AMD SEV-SNP confidential computing guests define the notion of accepting memory before using it and thus preventing a whole set of attacks against such guests like memory replay and the like. There are a couple of strategies of how memory should be accepted - the current implementation does an on-demand way of accepting. * tag 'x86_cc_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: virt: sevguest: Add CONFIG_CRYPTO dependency x86/efi: Safely enable unaccepted memory in UEFI x86/sev: Add SNP-specific unaccepted memory support x86/sev: Use large PSC requests if applicable x86/sev: Allow for use of the early boot GHCB for PSC requests x86/sev: Put PSC struct on the stack in prep for unaccepted memory support x86/sev: Fix calculation of end address based on number of pages x86/tdx: Add unaccepted memory support x86/tdx: Refactor try_accept_one() x86/tdx: Make _tdx_hypercall() and __tdx_module_call() available in boot stub efi/unaccepted: Avoid load_unaligned_zeropad() stepping into unaccepted memory efi: Add unaccepted memory support x86/boot/compressed: Handle unaccepted memory efi/libstub: Implement support for unaccepted memory efi/x86: Get full memory map in allocate_e820() mm: Add support for unaccepted memory |
||
|
Kirill A. Shutemov
|
195edce08b |
x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad()
tl;dr: There is a race in the TDX private<=>shared conversion code
which could kill the TDX guest. Fix it by changing conversion
ordering to eliminate the window.
TDX hardware maintains metadata to track which pages are private and
shared. Additionally, TDX guests use the guest x86 page tables to
specify whether a given mapping is intended to be private or shared.
Bad things happen when the intent and metadata do not match.
So there are two thing in play:
1. "the page" -- the physical TDX page metadata
2. "the mapping" -- the guest-controlled x86 page table intent
For instance, an unrecoverable exit to VMM occurs if a guest touches a
private mapping that points to a shared physical page.
In summary:
* Private mapping => Private Page == OK (obviously)
* Shared mapping => Shared Page == OK (obviously)
* Private mapping => Shared Page == BIG BOOM!
* Shared mapping => Private Page == OK-ish
(It will read generate a recoverable #VE via handle_mmio())
Enter load_unaligned_zeropad(). It can touch memory that is adjacent but
otherwise unrelated to the memory it needs to touch. It will cause one
of those unrecoverable exits (aka. BIG BOOM) if it blunders into a
shared mapping pointing to a private page.
This is a problem when __set_memory_enc_pgtable() converts pages from
shared to private. It first changes the mapping and second modifies
the TDX page metadata. It's moving from:
* Shared mapping => Shared Page == OK
to:
* Private mapping => Shared Page == BIG BOOM!
This means that there is a window with a shared mapping pointing to a
private page where load_unaligned_zeropad() can strike.
Add a TDX handler for guest.enc_status_change_prepare(). This converts
the page from shared to private *before* the page becomes private. This
ensures that there is never a private mapping to a shared page.
Leave a guest.enc_status_change_finish() in place but only use it for
private=>shared conversions. This will delay updating the TDX metadata
marking the page private until *after* the mapping matches the metadata.
This also ensures that there is never a private mapping to a shared page.
[ dhansen: rewrite changelog ]
Fixes:
|
||
|
Kirill A. Shutemov
|
75d090fd16 |
x86/tdx: Add unaccepted memory support
Hookup TDX-specific code to accept memory. Accepting the memory is done with ACCEPT_PAGE module call on every page in the range. MAP_GPA hypercall is not required as the unaccepted memory is considered private already. Extract the part of tdx_enc_status_changed() that does memory acceptance in a new helper. Move the helper tdx-shared.c. It is going to be used by both main kernel and decompressor. [ bp: Fix the INTEL_TDX_GUEST=y, KVM_GUEST=n build. ] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230606142637.5171-10-kirill.shutemov@linux.intel.com |
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|
Kirill A. Shutemov
|
c2b353ae24 |
x86/tdx: Refactor try_accept_one()
Rework try_accept_one() to return accepted size instead of modifying 'start' inside the helper. It makes 'start' in-only argument and streamlines code on the caller side. Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20230606142637.5171-9-kirill.shutemov@linux.intel.com |
||
|
Kirill A. Shutemov
|
ff40b5769a |
x86/tdx: Make _tdx_hypercall() and __tdx_module_call() available in boot stub
Memory acceptance requires a hypercall and one or multiple module calls. Make helpers for the calls available in boot stub. It has to accept memory where kernel image and initrd are placed. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20230606142637.5171-8-kirill.shutemov@linux.intel.com |
||
Thomas Gleixner
|
ff3cfcb0d4 |
x86/smpboot: Fix the parallel bringup decision
The decision to allow parallel bringup of secondary CPUs checks
CC_ATTR_GUEST_STATE_ENCRYPT to detect encrypted guests. Those cannot use
parallel bootup because accessing the local APIC is intercepted and raises
a #VC or #VE, which cannot be handled at that point.
The check works correctly, but only for AMD encrypted guests. TDX does not
set that flag.
As there is no real connection between CC attributes and the inability to
support parallel bringup, replace this with a generic control flag in
x86_cpuinit and let SEV-ES and TDX init code disable it.
Fixes:
|
||
Nikolay Borisov
|
122333d6bd |
x86/tdx: Wrap exit reason with hcall_func()
TDX reuses VMEXIT "reasons" in its guest->host hypercall ABI. This is confusing because there might not be a VMEXIT involved at *all*. These instances are supposed to document situation and reduce confusion by wrapping VMEXIT reasons with hcall_func(). The decompression code does not follow this convention. Unify the TDX decompression code with the other TDX use of VMEXIT reasons. No functional changes. Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: https://lore.kernel.org/all/20230505120332.1429957-1-nik.borisov%40suse.com |
||
|
Borislav Petkov (AMD)
|
da86eb9611 |
x86/coco: Get rid of accessor functions
cc_vendor is __ro_after_init and thus can be used directly. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230508121957.32341-1-bp@alien8.de |
||
|
Borislav Petkov (AMD)
|
1eaf282e2c |
x86/coco: Mark cc_platform_has() and descendants noinstr
Those will be used in code regions where instrumentation is not allowed so mark them as such. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230328201712.25852-2-bp@alien8.de |
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|
Linus Torvalds
|
7b664cc38e |
* Do conditional __tdx_hypercall() 'output' processing via an
assembly macro argument rather than a runtime register.
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Merge tag 'x86_tdx_for_6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 tdx update from Dave Hansen:
"The original tdx hypercall assembly code took two flags in %RSI to
tweak its behavior at runtime. PeterZ recently axed one flag in commit
|
||
|
Linus Torvalds
|
de10553fce |
x86 APIC updates:
- Fix the incorrect handling of atomic offset updates in
reserve_eilvt_offset()
The check for the return value of atomic_cmpxchg() is not compared
against the old value, it is compared against the new value, which
makes it two round on success.
Convert it to atomic_try_cmpxchg() which does the right thing.
- Handle IO/APIC less systems correctly
When IO/APIC is not advertised by ACPI then the computation of the lower
bound for dynamically allocated interrupts like MSI goes wrong.
This lower bound is used to exclude the IO/APIC legacy GSI space as that
must stay reserved for the legacy interrupts.
In case that the system, e.g. VM, does not advertise an IO/APIC the
lower bound stays at 0.
0 is an invalid interrupt number except for the legacy timer interrupt
on x86. The return value is unchecked in the core code, so it ends up
to allocate interrupt number 0 which is subsequently considered to be
invalid by the caller, e.g. the MSI allocation code.
A similar problem was already cured for device tree based systems years
ago, but that missed - or did not envision - the zero IO/APIC case.
Consolidate the zero check and return the provided "from" argument to the
core code call site, which is guaranteed to be greater than 0.
- Simplify the X2APIC cluster CPU mask logic for CPU hotplug
Per cluster CPU masks are required for X2APIC in cluster mode to
determine the correct cluster for a target CPU when calculating the
destination for IPIs
These masks are established when CPUs are borught up. The first CPU in a
cluster must allocate a new cluster CPU mask. As this happens during the
early startup of a CPU, where memory allocations cannot be done, the
mask has to be allocated by the control CPU.
The current implementation allocates a clustermask just in case and if
the to be brought up CPU is the first in a cluster the CPU takes over
this allocation from a global pointer.
This works nicely in the fully serialized CPU bringup scenario which is
used today, but would fail completely for parallel bringup of CPUs.
The cluster association of a CPU can be computed from the APIC ID which
is enumerated by ACPI/MADT.
So the cluster CPU masks can be preallocated and associated upfront and
the upcoming CPUs just need to set their corresponding bit.
Aside of preparing for parallel bringup this is a valuable
simplification on its own.
- Remove global variables which control the early startup of secondary
CPUs on 64-bit
The only information which is needed by a starting CPU is the Linux CPU
number. The CPU number allows it to retrieve the rest of the required
data from already existing per CPU storage.
So instead of initial_stack, early_gdt_desciptor and initial_gs provide
a new variable smpboot_control which contains the Linux CPU number for
now. The starting CPU can retrieve and compute all required information
for startup from there.
Aside of being a cleanup, this is also preparing for parallel CPU
bringup, where starting CPUs will look up their Linux CPU number via the
APIC ID, when smpboot_control has the corresponding control bit set.
- Make cc_vendor globally accesible
Subsequent parallel bringup changes require access to cc_vendor because
confidental computing platforms need special treatment in the early
startup phase vs. CPUID and APCI ID readouts.
The change makes cc_vendor global and provides stub accessors in case
that CONFIG_ARCH_HAS_CC_PLATFORM is not set.
This was merged from the x86/cc branch in anticipation of further
parallel bringup commits which require access to cc_vendor. Due to late
discoveries of fundamental issue with those patches these commits never
happened.
The merge commit is unfortunately in the middle of the APIC commits so
unraveling it would have required a rebase or revert. As the parallel
bringup seems to be well on its way for 6.5 this would be just pointless
churn. As the commit does not contain any functional change it's not a
risk to keep it.
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Merge tag 'x86-apic-2023-04-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 APIC updates from Thomas Gleixner:
- Fix the incorrect handling of atomic offset updates in
reserve_eilvt_offset()
The check for the return value of atomic_cmpxchg() is not compared
against the old value, it is compared against the new value, which
makes it two round on success.
Convert it to atomic_try_cmpxchg() which does the right thing.
- Handle IO/APIC less systems correctly
When IO/APIC is not advertised by ACPI then the computation of the
lower bound for dynamically allocated interrupts like MSI goes wrong.
This lower bound is used to exclude the IO/APIC legacy GSI space as
that must stay reserved for the legacy interrupts.
In case that the system, e.g. VM, does not advertise an IO/APIC the
lower bound stays at 0.
0 is an invalid interrupt number except for the legacy timer
interrupt on x86. The return value is unchecked in the core code, so
it ends up to allocate interrupt number 0 which is subsequently
considered to be invalid by the caller, e.g. the MSI allocation code.
A similar problem was already cured for device tree based systems
years ago, but that missed - or did not envision - the zero IO/APIC
case.
Consolidate the zero check and return the provided "from" argument to
the core code call site, which is guaranteed to be greater than 0.
- Simplify the X2APIC cluster CPU mask logic for CPU hotplug
Per cluster CPU masks are required for X2APIC in cluster mode to
determine the correct cluster for a target CPU when calculating the
destination for IPIs
These masks are established when CPUs are borught up. The first CPU
in a cluster must allocate a new cluster CPU mask. As this happens
during the early startup of a CPU, where memory allocations cannot be
done, the mask has to be allocated by the control CPU.
The current implementation allocates a clustermask just in case and
if the to be brought up CPU is the first in a cluster the CPU takes
over this allocation from a global pointer.
This works nicely in the fully serialized CPU bringup scenario which
is used today, but would fail completely for parallel bringup of
CPUs.
The cluster association of a CPU can be computed from the APIC ID
which is enumerated by ACPI/MADT.
So the cluster CPU masks can be preallocated and associated upfront
and the upcoming CPUs just need to set their corresponding bit.
Aside of preparing for parallel bringup this is a valuable
simplification on its own.
- Remove global variables which control the early startup of secondary
CPUs on 64-bit
The only information which is needed by a starting CPU is the Linux
CPU number. The CPU number allows it to retrieve the rest of the
required data from already existing per CPU storage.
So instead of initial_stack, early_gdt_desciptor and initial_gs
provide a new variable smpboot_control which contains the Linux CPU
number for now. The starting CPU can retrieve and compute all
required information for startup from there.
Aside of being a cleanup, this is also preparing for parallel CPU
bringup, where starting CPUs will look up their Linux CPU number via
the APIC ID, when smpboot_control has the corresponding control bit
set.
- Make cc_vendor globally accesible
Subsequent parallel bringup changes require access to cc_vendor
because confidental computing platforms need special treatment in the
early startup phase vs. CPUID and APCI ID readouts.
The change makes cc_vendor global and provides stub accessors in case
that CONFIG_ARCH_HAS_CC_PLATFORM is not set.
This was merged from the x86/cc branch in anticipation of further
parallel bringup commits which require access to cc_vendor. Due to
late discoveries of fundamental issue with those patches these
commits never happened.
The merge commit is unfortunately in the middle of the APIC commits
so unraveling it would have required a rebase or revert. As the
parallel bringup seems to be well on its way for 6.5 this would be
just pointless churn. As the commit does not contain any functional
change it's not a risk to keep it.
* tag 'x86-apic-2023-04-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ioapic: Don't return 0 from arch_dynirq_lower_bound()
x86/apic: Fix atomic update of offset in reserve_eilvt_offset()
x86/coco: Export cc_vendor
x86/smpboot: Reference count on smpboot_setup_warm_reset_vector()
x86/smpboot: Remove initial_gs
x86/smpboot: Remove early_gdt_descr on 64-bit
x86/smpboot: Remove initial_stack on 64-bit
x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel
|
||
|
Borislav Petkov (AMD)
|
3d91c53729 |
x86/coco: Export cc_vendor
It will be used in different checks in future changes. Export it directly and provide accessor functions and stubs so this can be used in general code when CONFIG_ARCH_HAS_CC_PLATFORM is not set. No functional changes. [ tglx: Add accessor functions ] Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230318115634.9392-2-bp@alien8.de |
||
Michael Kelley
|
812b0597fb |
x86/hyperv: Change vTOM handling to use standard coco mechanisms
Hyper-V guests on AMD SEV-SNP hardware have the option of using the "virtual Top Of Memory" (vTOM) feature specified by the SEV-SNP architecture. With vTOM, shared vs. private memory accesses are controlled by splitting the guest physical address space into two halves. vTOM is the dividing line where the uppermost bit of the physical address space is set; e.g., with 47 bits of guest physical address space, vTOM is 0x400000000000 (bit 46 is set). Guest physical memory is accessible at two parallel physical addresses -- one below vTOM and one above vTOM. Accesses below vTOM are private (encrypted) while accesses above vTOM are shared (decrypted). In this sense, vTOM is like the GPA.SHARED bit in Intel TDX. Support for Hyper-V guests using vTOM was added to the Linux kernel in two patch sets[1][2]. This support treats the vTOM bit as part of the physical address. For accessing shared (decrypted) memory, these patch sets create a second kernel virtual mapping that maps to physical addresses above vTOM. A better approach is to treat the vTOM bit as a protection flag, not as part of the physical address. This new approach is like the approach for the GPA.SHARED bit in Intel TDX. Rather than creating a second kernel virtual mapping, the existing mapping is updated using recently added coco mechanisms. When memory is changed between private and shared using set_memory_decrypted() and set_memory_encrypted(), the PTEs for the existing kernel mapping are changed to add or remove the vTOM bit in the guest physical address, just as with TDX. The hypercalls to change the memory status on the host side are made using the existing callback mechanism. Everything just works, with a minor tweak to map the IO-APIC to use private accesses. To accomplish the switch in approach, the following must be done: * Update Hyper-V initialization to set the cc_mask based on vTOM and do other coco initialization. * Update physical_mask so the vTOM bit is no longer treated as part of the physical address * Remove CC_VENDOR_HYPERV and merge the associated vTOM functionality under CC_VENDOR_AMD. Update cc_mkenc() and cc_mkdec() to set/clear the vTOM bit as a protection flag. * Code already exists to make hypercalls to inform Hyper-V about pages changing between shared and private. Update this code to run as a callback from __set_memory_enc_pgtable(). * Remove the Hyper-V special case from __set_memory_enc_dec() * Remove the Hyper-V specific call to swiotlb_update_mem_attributes() since mem_encrypt_init() will now do it. * Add a Hyper-V specific implementation of the is_private_mmio() callback that returns true for the IO-APIC and vTPM MMIO addresses [1] https://lore.kernel.org/all/20211025122116.264793-1-ltykernel@gmail.com/ [2] https://lore.kernel.org/all/20211213071407.314309-1-ltykernel@gmail.com/ [ bp: Touchups. ] Signed-off-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/1679838727-87310-7-git-send-email-mikelley@microsoft.com |
||
|
Kirill A. Shutemov
|
7a3a401874 |
x86/tdx: Drop flags from __tdx_hypercall()
After TDX_HCALL_ISSUE_STI got dropped, the only flag left is TDX_HCALL_HAS_OUTPUT. The flag indicates if the caller wants to see tdx_hypercall_args updated based on the hypercall output. Drop the flags and provide __tdx_hypercall_ret() that matches TDX_HCALL_HAS_OUTPUT semantics. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/20230321003511.9469-1-kirill.shutemov%40linux.intel.com |
||
|
Linus Torvalds
|
d8e473182a |
- Fixup comment typo
- Prevent unexpected #VE's from:
- Hosts removing perfectly good guest mappings (SEPT_VE_DISABLE
- Excessive #VE notifications (NOTIFY_ENABLES) which are
delivered via a #VE.
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Merge tag 'x86_tdx_for_6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull Intel Trust Domain Extensions (TDX) updates from Dave Hansen:
"Other than a minor fixup, the content here is to ensure that TDX
guests never see virtualization exceptions (#VE's) that might be
induced by the untrusted VMM.
This is a highly desirable property. Without it, #VE exception
handling would fall somewhere between NMIs, machine checks and total
insanity. With it, #VE handling remains pretty mundane.
Summary:
- Fixup comment typo
- Prevent unexpected #VE's from:
- Hosts removing perfectly good guest mappings (SEPT_VE_DISABLE)
- Excessive #VE notifications (NOTIFY_ENABLES) which are delivered
via a #VE"
* tag 'x86_tdx_for_6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall()
x86/tdx: Disable NOTIFY_ENABLES
x86/tdx: Relax SEPT_VE_DISABLE check for debug TD
x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE
x86/tdx: Expand __tdx_hypercall() to handle more arguments
x86/tdx: Refactor __tdx_hypercall() to allow pass down more arguments
x86/tdx: Add more registers to struct tdx_hypercall_args
x86/tdx: Fix typo in comment in __tdx_hypercall()
|
||
|
Kirill A. Shutemov
|
1e70c68037 |
x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall()
If compiled with CONFIG_FRAME_POINTER=y, objtool is not happy that
__tdx_hypercall() messes up RBP:
objtool: __tdx_hypercall+0x7f: return with modified stack frame
Rework the function to store TDX_HCALL_ flags on stack instead of RBP.
[ dhansen: minor changelog tweaks ]
Fixes:
|
||
Ingo Molnar
|
57a30218fa |
Linux 6.2-rc6
-----BEGIN PGP SIGNATURE----- iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAmPW7E8eHHRvcnZhbGRz QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGf7MIAI0JnHN9WvtEukSZ E6j6+cEGWxsvD6q0g3GPolaKOCw7hlv0pWcFJFcUAt0jebspMdxV2oUGJ8RYW7Lg nCcHvEVswGKLAQtQSWw52qotW6fUfMPsNYYB5l31sm1sKH4Cgss0W7l2HxO/1LvG TSeNHX53vNAZ8pVnFYEWCSXC9bzrmU/VALF2EV00cdICmfvjlgkELGXoLKJJWzUp s63fBHYGGURSgwIWOKStoO6HNo0j/F/wcSMx8leY8qDUtVKHj4v24EvSgxUSDBER ch3LiSQ6qf4sw/z7pqruKFthKOrlNmcc0phjiES0xwwGiNhLv0z3rAhc4OM2cgYh SDc/Y/c= =zpaD -----END PGP SIGNATURE----- Merge tag 'v6.2-rc6' into sched/core, to pick up fixes Pick up fixes before merging another batch of cpuidle updates. Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Kirill A. Shutemov
|
8de62af018 |
x86/tdx: Disable NOTIFY_ENABLES
== Background == There is a class of side-channel attacks against SGX enclaves called "SGX Step"[1]. These attacks create lots of exceptions inside of enclaves. Basically, run an in-enclave instruction, cause an exception. Over and over. There is a concern that a VMM could attack a TDX guest in the same way by causing lots of #VE's. The TDX architecture includes new countermeasures for these attacks. It basically counts the number of exceptions and can send another *special* exception once the number of VMM-induced #VE's hits a critical threshold[2]. == Problem == But, these special exceptions are independent of any action that the guest takes. They can occur anywhere that the guest executes. This includes sensitive areas like the entry code. The (non-paranoid) #VE handler is incapable of handling exceptions in these areas. == Solution == Fortunately, the special exceptions can be disabled by the guest via write to NOTIFY_ENABLES TDCS field. NOTIFY_ENABLES is disabled by default, but might be enabled by a bootloader, firmware or an earlier kernel before the current kernel runs. Disable NOTIFY_ENABLES feature explicitly and unconditionally. Any NOTIFY_ENABLES-based #VE's that occur before this point will end up in the early #VE exception handler and die due to unexpected exit reason. [1] https://github.com/jovanbulck/sgx-step [2] https://intel.github.io/ccc-linux-guest-hardening-docs/security-spec.html#safety-against-ve-in-kernel-code Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Dave Hansen <dave.hansen@intel.com> Link: https://lore.kernel.org/all/20230126221159.8635-8-kirill.shutemov%40linux.intel.com |