* Initial infrastructure for shadow stage-2 MMUs, as part of nested
virtualization enablement
* Support for userspace changes to the guest CTR_EL0 value, enabling
(in part) migration of VMs between heterogenous hardware
* Fixes + improvements to pKVM's FF-A proxy, adding support for v1.1 of
the protocol
* FPSIMD/SVE support for nested, including merged trap configuration
and exception routing
* New command-line parameter to control the WFx trap behavior under KVM
* Introduce kCFI hardening in the EL2 hypervisor
* Fixes + cleanups for handling presence/absence of FEAT_TCRX
* Miscellaneous fixes + documentation updates
LoongArch:
* Add paravirt steal time support.
* Add support for KVM_DIRTY_LOG_INITIALLY_SET.
* Add perf kvm-stat support for loongarch.
RISC-V:
* Redirect AMO load/store access fault traps to guest
* perf kvm stat support
* Use guest files for IMSIC virtualization, when available
ONE_REG support for the Zimop, Zcmop, Zca, Zcf, Zcd, Zcb and Zawrs ISA
extensions is coming through the RISC-V tree.
s390:
* Assortment of tiny fixes which are not time critical
x86:
* Fixes for Xen emulation.
* Add a global struct to consolidate tracking of host values, e.g. EFER
* Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC
bus frequency, because TDX.
* Print the name of the APICv/AVIC inhibits in the relevant tracepoint.
* Clean up KVM's handling of vendor specific emulation to consistently act on
"compatible with Intel/AMD", versus checking for a specific vendor.
* Drop MTRR virtualization, and instead always honor guest PAT on CPUs
that support self-snoop.
* Update to the newfangled Intel CPU FMS infrastructure.
* Don't advertise IA32_PERF_GLOBAL_OVF_CTRL as an MSR-to-be-saved, as it reads
'0' and writes from userspace are ignored.
* Misc cleanups
x86 - MMU:
* Small cleanups, renames and refactoring extracted from the upcoming
Intel TDX support.
* Don't allocate kvm_mmu_page.shadowed_translation for shadow pages that can't
hold leafs SPTEs.
* Unconditionally drop mmu_lock when allocating TDP MMU page tables for eager
page splitting, to avoid stalling vCPUs when splitting huge pages.
* Bug the VM instead of simply warning if KVM tries to split a SPTE that is
non-present or not-huge. KVM is guaranteed to end up in a broken state
because the callers fully expect a valid SPTE, it's all but dangerous
to let more MMU changes happen afterwards.
x86 - AMD:
* Make per-CPU save_area allocations NUMA-aware.
* Force sev_es_host_save_area() to be inlined to avoid calling into an
instrumentable function from noinstr code.
* Base support for running SEV-SNP guests. API-wise, this includes
a new KVM_X86_SNP_VM type, encrypting/measure the initial image into
guest memory, and finalizing it before launching it. Internally,
there are some gmem/mmu hooks needed to prepare gmem-allocated pages
before mapping them into guest private memory ranges.
This includes basic support for attestation guest requests, enough to
say that KVM supports the GHCB 2.0 specification.
There is no support yet for loading into the firmware those signing
keys to be used for attestation requests, and therefore no need yet
for the host to provide certificate data for those keys. To support
fetching certificate data from userspace, a new KVM exit type will be
needed to handle fetching the certificate from userspace. An attempt to
define a new KVM_EXIT_COCO/KVM_EXIT_COCO_REQ_CERTS exit type to handle
this was introduced in v1 of this patchset, but is still being discussed
by community, so for now this patchset only implements a stub version
of SNP Extended Guest Requests that does not provide certificate data.
x86 - Intel:
* Remove an unnecessary EPT TLB flush when enabling hardware.
* Fix a series of bugs that cause KVM to fail to detect nested pending posted
interrupts as valid wake eents for a vCPU executing HLT in L2 (with
HLT-exiting disable by L1).
* KVM: x86: Suppress MMIO that is triggered during task switch emulation
Explicitly suppress userspace emulated MMIO exits that are triggered when
emulating a task switch as KVM doesn't support userspace MMIO during
complex (multi-step) emulation. Silently ignoring the exit request can
result in the WARN_ON_ONCE(vcpu->mmio_needed) firing if KVM exits to
userspace for some other reason prior to purging mmio_needed.
See commit 0dc902267c ("KVM: x86: Suppress pending MMIO write exits if
emulator detects exception") for more details on KVM's limitations with
respect to emulated MMIO during complex emulator flows.
Generic:
* Rename the AS_UNMOVABLE flag that was introduced for KVM to AS_INACCESSIBLE,
because the special casing needed by these pages is not due to just
unmovability (and in fact they are only unmovable because the CPU cannot
access them).
* New ioctl to populate the KVM page tables in advance, which is useful to
mitigate KVM page faults during guest boot or after live migration.
The code will also be used by TDX, but (probably) not through the ioctl.
* Enable halt poll shrinking by default, as Intel found it to be a clear win.
* Setup empty IRQ routing when creating a VM to avoid having to synchronize
SRCU when creating a split IRQCHIP on x86.
* Rework the sched_in/out() paths to replace kvm_arch_sched_in() with a flag
that arch code can use for hooking both sched_in() and sched_out().
* Take the vCPU @id as an "unsigned long" instead of "u32" to avoid
truncating a bogus value from userspace, e.g. to help userspace detect bugs.
* Mark a vCPU as preempted if and only if it's scheduled out while in the
KVM_RUN loop, e.g. to avoid marking it preempted and thus writing guest
memory when retrieving guest state during live migration blackout.
Selftests:
* Remove dead code in the memslot modification stress test.
* Treat "branch instructions retired" as supported on all AMD Family 17h+ CPUs.
* Print the guest pseudo-RNG seed only when it changes, to avoid spamming the
log for tests that create lots of VMs.
* Make the PMU counters test less flaky when counting LLC cache misses by
doing CLFLUSH{OPT} in every loop iteration.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"ARM:
- Initial infrastructure for shadow stage-2 MMUs, as part of nested
virtualization enablement
- Support for userspace changes to the guest CTR_EL0 value, enabling
(in part) migration of VMs between heterogenous hardware
- Fixes + improvements to pKVM's FF-A proxy, adding support for v1.1
of the protocol
- FPSIMD/SVE support for nested, including merged trap configuration
and exception routing
- New command-line parameter to control the WFx trap behavior under
KVM
- Introduce kCFI hardening in the EL2 hypervisor
- Fixes + cleanups for handling presence/absence of FEAT_TCRX
- Miscellaneous fixes + documentation updates
LoongArch:
- Add paravirt steal time support
- Add support for KVM_DIRTY_LOG_INITIALLY_SET
- Add perf kvm-stat support for loongarch
RISC-V:
- Redirect AMO load/store access fault traps to guest
- perf kvm stat support
- Use guest files for IMSIC virtualization, when available
s390:
- Assortment of tiny fixes which are not time critical
x86:
- Fixes for Xen emulation
- Add a global struct to consolidate tracking of host values, e.g.
EFER
- Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the
effective APIC bus frequency, because TDX
- Print the name of the APICv/AVIC inhibits in the relevant
tracepoint
- Clean up KVM's handling of vendor specific emulation to
consistently act on "compatible with Intel/AMD", versus checking
for a specific vendor
- Drop MTRR virtualization, and instead always honor guest PAT on
CPUs that support self-snoop
- Update to the newfangled Intel CPU FMS infrastructure
- Don't advertise IA32_PERF_GLOBAL_OVF_CTRL as an MSR-to-be-saved, as
it reads '0' and writes from userspace are ignored
- Misc cleanups
x86 - MMU:
- Small cleanups, renames and refactoring extracted from the upcoming
Intel TDX support
- Don't allocate kvm_mmu_page.shadowed_translation for shadow pages
that can't hold leafs SPTEs
- Unconditionally drop mmu_lock when allocating TDP MMU page tables
for eager page splitting, to avoid stalling vCPUs when splitting
huge pages
- Bug the VM instead of simply warning if KVM tries to split a SPTE
that is non-present or not-huge. KVM is guaranteed to end up in a
broken state because the callers fully expect a valid SPTE, it's
all but dangerous to let more MMU changes happen afterwards
x86 - AMD:
- Make per-CPU save_area allocations NUMA-aware
- Force sev_es_host_save_area() to be inlined to avoid calling into
an instrumentable function from noinstr code
- Base support for running SEV-SNP guests. API-wise, this includes a
new KVM_X86_SNP_VM type, encrypting/measure the initial image into
guest memory, and finalizing it before launching it. Internally,
there are some gmem/mmu hooks needed to prepare gmem-allocated
pages before mapping them into guest private memory ranges
This includes basic support for attestation guest requests, enough
to say that KVM supports the GHCB 2.0 specification
There is no support yet for loading into the firmware those signing
keys to be used for attestation requests, and therefore no need yet
for the host to provide certificate data for those keys.
To support fetching certificate data from userspace, a new KVM exit
type will be needed to handle fetching the certificate from
userspace.
An attempt to define a new KVM_EXIT_COCO / KVM_EXIT_COCO_REQ_CERTS
exit type to handle this was introduced in v1 of this patchset, but
is still being discussed by community, so for now this patchset
only implements a stub version of SNP Extended Guest Requests that
does not provide certificate data
x86 - Intel:
- Remove an unnecessary EPT TLB flush when enabling hardware
- Fix a series of bugs that cause KVM to fail to detect nested
pending posted interrupts as valid wake eents for a vCPU executing
HLT in L2 (with HLT-exiting disable by L1)
- KVM: x86: Suppress MMIO that is triggered during task switch
emulation
Explicitly suppress userspace emulated MMIO exits that are
triggered when emulating a task switch as KVM doesn't support
userspace MMIO during complex (multi-step) emulation
Silently ignoring the exit request can result in the
WARN_ON_ONCE(vcpu->mmio_needed) firing if KVM exits to userspace
for some other reason prior to purging mmio_needed
See commit 0dc902267c ("KVM: x86: Suppress pending MMIO write
exits if emulator detects exception") for more details on KVM's
limitations with respect to emulated MMIO during complex emulator
flows
Generic:
- Rename the AS_UNMOVABLE flag that was introduced for KVM to
AS_INACCESSIBLE, because the special casing needed by these pages
is not due to just unmovability (and in fact they are only
unmovable because the CPU cannot access them)
- New ioctl to populate the KVM page tables in advance, which is
useful to mitigate KVM page faults during guest boot or after live
migration. The code will also be used by TDX, but (probably) not
through the ioctl
- Enable halt poll shrinking by default, as Intel found it to be a
clear win
- Setup empty IRQ routing when creating a VM to avoid having to
synchronize SRCU when creating a split IRQCHIP on x86
- Rework the sched_in/out() paths to replace kvm_arch_sched_in() with
a flag that arch code can use for hooking both sched_in() and
sched_out()
- Take the vCPU @id as an "unsigned long" instead of "u32" to avoid
truncating a bogus value from userspace, e.g. to help userspace
detect bugs
- Mark a vCPU as preempted if and only if it's scheduled out while in
the KVM_RUN loop, e.g. to avoid marking it preempted and thus
writing guest memory when retrieving guest state during live
migration blackout
Selftests:
- Remove dead code in the memslot modification stress test
- Treat "branch instructions retired" as supported on all AMD Family
17h+ CPUs
- Print the guest pseudo-RNG seed only when it changes, to avoid
spamming the log for tests that create lots of VMs
- Make the PMU counters test less flaky when counting LLC cache
misses by doing CLFLUSH{OPT} in every loop iteration"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (227 commits)
crypto: ccp: Add the SNP_VLEK_LOAD command
KVM: x86/pmu: Add kvm_pmu_call() to simplify static calls of kvm_pmu_ops
KVM: x86: Introduce kvm_x86_call() to simplify static calls of kvm_x86_ops
KVM: x86: Replace static_call_cond() with static_call()
KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event
x86/sev: Move sev_guest.h into common SEV header
KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event
KVM: x86: Suppress MMIO that is triggered during task switch emulation
KVM: x86/mmu: Clean up make_huge_page_split_spte() definition and intro
KVM: x86/mmu: Bug the VM if KVM tries to split a !hugepage SPTE
KVM: selftests: x86: Add test for KVM_PRE_FAULT_MEMORY
KVM: x86: Implement kvm_arch_vcpu_pre_fault_memory()
KVM: x86/mmu: Make kvm_mmu_do_page_fault() return mapped level
KVM: x86/mmu: Account pf_{fixed,emulate,spurious} in callers of "do page fault"
KVM: x86/mmu: Bump pf_taken stat only in the "real" page fault handler
KVM: Add KVM_PRE_FAULT_MEMORY vcpu ioctl to pre-populate guest memory
KVM: Document KVM_PRE_FAULT_MEMORY ioctl
mm, virt: merge AS_UNMOVABLE and AS_INACCESSIBLE
perf kvm: Add kvm-stat for loongarch64
LoongArch: KVM: Add PV steal time support in guest side
...
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
2c9b351240