Commit Graph

102 Commits

Author SHA1 Message Date
Mark Brown
e35ac9d0b5 arm64/sve: Use correct size when reinitialising SVE state
When we need a buffer for SVE register state we call sve_alloc() to make
sure that one is there. In order to avoid repeated allocations and frees
we keep the buffer around unless we change vector length and just memset()
it to ensure a clean register state. The function that deals with this
takes the task to operate on as an argument, however in the case where we
do a memset() we initialise using the SVE state size for the current task
rather than the task passed as an argument.

This is only an issue in the case where we are setting the register state
for a task via ptrace and the task being configured has a different vector
length to the task tracing it. In the case where the buffer is larger in
the traced process we will leak old state from the traced process to
itself, in the case where the buffer is smaller in the traced process we
will overflow the buffer and corrupt memory.

Fixes: bc0ee47603 ("arm64/sve: Core task context handling")
Cc: <stable@vger.kernel.org> # 4.15.x
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210909165356.10675-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-09-16 17:34:46 +01:00
Mark Brown
7559b7d7d6 arm64/sve: Better handle failure to allocate SVE register storage
Currently we "handle" failure to allocate the SVE register storage by
doing a BUG_ON() and hoping for the best. This is obviously not great and
the memory allocation failure will already be loud enough without the
BUG_ON(). As the comment says it is a corner case but let's try to do a bit
better, remove the BUG_ON() and add code to handle the failure in the
callers.

For the ptrace and signal code we can return -ENOMEM gracefully however
we have no real error reporting path available to us for the SVE access
trap so instead generate a SIGKILL if the allocation fails there. This
at least means that we won't try to soldier on and end up trying to
access the nonexistant state and while it's obviously not ideal for
userspace SIGKILL doesn't allow any handling so minimises the ABI
impact, making it easier to improve the interface later if we come up
with a better idea.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210824153417.18371-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-08-24 16:44:30 +01:00
Mark Brown
b24b520509 arm64/sve: Make fpsimd_bind_task_to_cpu() static
This function is not referenced outside fpsimd.c so can be static, making
it that little bit easier to follow what is called from where.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210730165846.18558-1-broonie@kernel.org
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-08-02 17:48:16 +01:00
Mark Brown
ad4711f962 arm64/sve: Skip flushing Z registers with 128 bit vectors
When the SVE vector length is 128 bits then there are no bits in the Z
registers which are not shared with the V registers so we can skip them
when zeroing state not shared with FPSIMD, this results in a minor
performance improvement.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210512151131.27877-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2021-05-26 20:04:28 +01:00
Catalin Marinas
a1e1eddef2 Merge branches 'for-next/misc', 'for-next/kselftest', 'for-next/xntable', 'for-next/vdso', 'for-next/fiq', 'for-next/epan', 'for-next/kasan-vmalloc', 'for-next/fgt-boot-init', 'for-next/vhe-only' and 'for-next/neon-softirqs-disabled', remote-tracking branch 'arm64/for-next/perf' into for-next/core
* for-next/misc:
  : Miscellaneous patches
  arm64/sve: Add compile time checks for SVE hooks in generic functions
  arm64/kernel/probes: Use BUG_ON instead of if condition followed by BUG.
  arm64/sve: Remove redundant system_supports_sve() tests
  arm64: mte: Remove unused mte_assign_mem_tag_range()
  arm64: Add __init section marker to some functions
  arm64/sve: Rework SVE access trap to convert state in registers
  docs: arm64: Fix a grammar error
  arm64: smp: Add missing prototype for some smp.c functions
  arm64: setup: name `tcr` register
  arm64: setup: name `mair` register
  arm64: stacktrace: Move start_backtrace() out of the header
  arm64: barrier: Remove spec_bar() macro
  arm64: entry: remove test_irqs_unmasked macro
  ARM64: enable GENERIC_FIND_FIRST_BIT
  arm64: defconfig: Use DEBUG_INFO_REDUCED

* for-next/kselftest:
  : Various kselftests for arm64
  kselftest: arm64: Add BTI tests
  kselftest/arm64: mte: Report filename on failing temp file creation
  kselftest/arm64: mte: Fix clang warning
  kselftest/arm64: mte: Makefile: Fix clang compilation
  kselftest/arm64: mte: Output warning about failing compiler
  kselftest/arm64: mte: Use cross-compiler if specified
  kselftest/arm64: mte: Fix MTE feature detection
  kselftest/arm64: mte: common: Fix write() warnings
  kselftest/arm64: mte: user_mem: Fix write() warning
  kselftest/arm64: mte: ksm_options: Fix fscanf warning
  kselftest/arm64: mte: Fix pthread linking
  kselftest/arm64: mte: Fix compilation with native compiler

* for-next/xntable:
  : Add hierarchical XN permissions for all page tables
  arm64: mm: use XN table mapping attributes for user/kernel mappings
  arm64: mm: use XN table mapping attributes for the linear region
  arm64: mm: add missing P4D definitions and use them consistently

* for-next/vdso:
  : Minor improvements to the compat vdso and sigpage
  arm64: compat: Poison the compat sigpage
  arm64: vdso: Avoid ISB after reading from cntvct_el0
  arm64: compat: Allow signal page to be remapped
  arm64: vdso: Remove redundant calls to flush_dcache_page()
  arm64: vdso: Use GFP_KERNEL for allocating compat vdso and signal pages

* for-next/fiq:
  : Support arm64 FIQ controller registration
  arm64: irq: allow FIQs to be handled
  arm64: Always keep DAIF.[IF] in sync
  arm64: entry: factor irq triage logic into macros
  arm64: irq: rework root IRQ handler registration
  arm64: don't use GENERIC_IRQ_MULTI_HANDLER
  genirq: Allow architectures to override set_handle_irq() fallback

* for-next/epan:
  : Support for Enhanced PAN (execute-only permissions)
  arm64: Support execute-only permissions with Enhanced PAN

* for-next/kasan-vmalloc:
  : Support CONFIG_KASAN_VMALLOC on arm64
  arm64: Kconfig: select KASAN_VMALLOC if KANSAN_GENERIC is enabled
  arm64: kaslr: support randomized module area with KASAN_VMALLOC
  arm64: Kconfig: support CONFIG_KASAN_VMALLOC
  arm64: kasan: abstract _text and _end to KERNEL_START/END
  arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC

* for-next/fgt-boot-init:
  : Booting clarifications and fine grained traps setup
  arm64: Require that system registers at all visible ELs be initialized
  arm64: Disable fine grained traps on boot
  arm64: Document requirements for fine grained traps at boot

* for-next/vhe-only:
  : Dealing with VHE-only CPUs (a.k.a. M1)
  arm64: Get rid of CONFIG_ARM64_VHE
  arm64: Cope with CPUs stuck in VHE mode
  arm64: cpufeature: Allow early filtering of feature override

* arm64/for-next/perf:
  arm64: perf: Remove redundant initialization in perf_event.c
  perf/arm_pmu_platform: Clean up with dev_printk
  perf/arm_pmu_platform: Fix error handling
  perf/arm_pmu_platform: Use dev_err_probe() for IRQ errors
  docs: perf: Address some html build warnings
  docs: perf: Add new description on HiSilicon uncore PMU v2
  drivers/perf: hisi: Add support for HiSilicon PA PMU driver
  drivers/perf: hisi: Add support for HiSilicon SLLC PMU driver
  drivers/perf: hisi: Update DDRC PMU for programmable counter
  drivers/perf: hisi: Add new functions for HHA PMU
  drivers/perf: hisi: Add new functions for L3C PMU
  drivers/perf: hisi: Add PMU version for uncore PMU drivers.
  drivers/perf: hisi: Refactor code for more uncore PMUs
  drivers/perf: hisi: Remove unnecessary check of counter index
  drivers/perf: Simplify the SMMUv3 PMU event attributes
  drivers/perf: convert sysfs sprintf family to sysfs_emit
  drivers/perf: convert sysfs scnprintf family to sysfs_emit_at() and sysfs_emit()
  drivers/perf: convert sysfs snprintf family to sysfs_emit

* for-next/neon-softirqs-disabled:
  : Run kernel mode SIMD with softirqs disabled
  arm64: fpsimd: run kernel mode NEON with softirqs disabled
  arm64: assembler: introduce wxN aliases for wN registers
  arm64: assembler: remove conditional NEON yield macros
2021-04-15 14:00:38 +01:00
Mark Brown
087dfa5ca7 arm64/sve: Add compile time checks for SVE hooks in generic functions
The FPSIMD code was relying on IS_ENABLED() checks in system_suppors_sve()
to cause the compiler to delete references to SVE functions in some places,
add explicit IS_ENABLED() checks back.

Fixes: ef9c5d0979 ("arm64/sve: Remove redundant system_supports_sve() tests")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210415121742.36628-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-04-15 13:56:30 +01:00
Mark Brown
ef9c5d0979 arm64/sve: Remove redundant system_supports_sve() tests
Currently there are a number of places in the SVE code where we check both
system_supports_sve() and TIF_SVE. This is a bit redundant given that we
should never get into a situation where we have set TIF_SVE without having
SVE support and it is not clear that silently ignoring a mistakenly set
TIF_SVE flag is the most sensible error handling approach. For now let's
just drop the system_supports_sve() checks since this will at least reduce
overhead a little.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210412172320.3315-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-04-13 12:51:33 +01:00
Ard Biesheuvel
13150149aa arm64: fpsimd: run kernel mode NEON with softirqs disabled
Kernel mode NEON can be used in task or softirq context, but only in
a non-nesting manner, i.e., softirq context is only permitted if the
interrupt was not taken at a point where the kernel was using the NEON
in task context.

This means all users of kernel mode NEON have to be aware of this
limitation, and either need to provide scalar fallbacks that may be much
slower (up to 20x for AES instructions) and potentially less safe, or
use an asynchronous interface that defers processing to a later time
when the NEON is guaranteed to be available.

Given that grabbing and releasing the NEON is cheap, we can relax this
restriction, by increasing the granularity of kernel mode NEON code, and
always disabling softirq processing while the NEON is being used in task
context.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210302090118.30666-4-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-04-12 11:55:34 +01:00
Mark Brown
cccb78ce89 arm64/sve: Rework SVE access trap to convert state in registers
When we enable SVE usage in userspace after taking a SVE access trap we
need to ensure that the portions of the register state that are not
shared with the FPSIMD registers are zeroed. Currently we do this by
forcing the FPSIMD registers to be saved to the task struct and converting
them there. This is wasteful in the common case where the task state is
loaded into the registers and we will immediately return to userspace
since we can initialise the SVE state directly in registers instead of
accessing multiple copies of the register state in memory.

Instead in that common case do the conversion in the registers and
update the task metadata so that we can return to userspace without
spilling the register state to memory unless there is some other reason
to do so.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210312190313.24598-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-04-08 17:43:43 +01:00
Peter Collingbourne
4b7a6ce71e arm64: reject prctl(PR_PAC_RESET_KEYS) on compat tasks
It doesn't make sense to issue prctl(PR_PAC_RESET_KEYS) on a
compat task because the 32-bit instruction set does not offer PAuth
instructions. For consistency with other 64-bit only prctls such as
{SET,GET}_TAGGED_ADDR_CTRL, reject the prctl on compat tasks.

Although this is a userspace-visible change, maybe it isn't too late
to make this change given that the hardware isn't available yet and
it's very unlikely that anyone has 32-bit software that actually
depends on this succeeding.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ie885a1ff84ab498cc9f62d6451e9f2cfd4b1d06a
Link: https://lore.kernel.org/r/20201014052430.11630-1-pcc@google.com
[will: Do the same for the SVE prctl()s]
Signed-off-by: Will Deacon <will@kernel.org>
2020-10-15 10:50:09 +01:00
Will Deacon
57b8b1b435 Merge branches 'for-next/acpi', 'for-next/boot', 'for-next/bpf', 'for-next/cpuinfo', 'for-next/fpsimd', 'for-next/misc', 'for-next/mm', 'for-next/pci', 'for-next/perf', 'for-next/ptrauth', 'for-next/sdei', 'for-next/selftests', 'for-next/stacktrace', 'for-next/svm', 'for-next/topology', 'for-next/tpyos' and 'for-next/vdso' into for-next/core
Remove unused functions and parameters from ACPI IORT code.
(Zenghui Yu via Lorenzo Pieralisi)
* for-next/acpi:
  ACPI/IORT: Remove the unused inline functions
  ACPI/IORT: Drop the unused @ops of iort_add_device_replay()

Remove redundant code and fix documentation of caching behaviour for the
HVC_SOFT_RESTART hypercall.
(Pingfan Liu)
* for-next/boot:
  Documentation/kvm/arm: improve description of HVC_SOFT_RESTART
  arm64/relocate_kernel: remove redundant code

Improve reporting of unexpected kernel traps due to BPF JIT failure.
(Will Deacon)
* for-next/bpf:
  arm64: Improve diagnostics when trapping BRK with FAULT_BRK_IMM

Improve robustness of user-visible HWCAP strings and their corresponding
numerical constants.
(Anshuman Khandual)
* for-next/cpuinfo:
  arm64/cpuinfo: Define HWCAP name arrays per their actual bit definitions

Cleanups to handling of SVE and FPSIMD register state in preparation
for potential future optimisation of handling across syscalls.
(Julien Grall)
* for-next/fpsimd:
  arm64/sve: Implement a helper to load SVE registers from FPSIMD state
  arm64/sve: Implement a helper to flush SVE registers
  arm64/fpsimdmacros: Allow the macro "for" to be used in more cases
  arm64/fpsimdmacros: Introduce a macro to update ZCR_EL1.LEN
  arm64/signal: Update the comment in preserve_sve_context
  arm64/fpsimd: Update documentation of do_sve_acc

Miscellaneous changes.
(Tian Tao and others)
* for-next/misc:
  arm64/mm: return cpu_all_mask when node is NUMA_NO_NODE
  arm64: mm: Fix missing-prototypes in pageattr.c
  arm64/fpsimd: Fix missing-prototypes in fpsimd.c
  arm64: hibernate: Remove unused including <linux/version.h>
  arm64/mm: Refactor {pgd, pud, pmd, pte}_ERROR()
  arm64: Remove the unused include statements
  arm64: get rid of TEXT_OFFSET
  arm64: traps: Add str of description to panic() in die()

Memory management updates and cleanups.
(Anshuman Khandual and others)
* for-next/mm:
  arm64: dbm: Invalidate local TLB when setting TCR_EL1.HD
  arm64: mm: Make flush_tlb_fix_spurious_fault() a no-op
  arm64/mm: Unify CONT_PMD_SHIFT
  arm64/mm: Unify CONT_PTE_SHIFT
  arm64/mm: Remove CONT_RANGE_OFFSET
  arm64/mm: Enable THP migration
  arm64/mm: Change THP helpers to comply with generic MM semantics
  arm64/mm/ptdump: Add address markers for BPF regions

Allow prefetchable PCI BARs to be exposed to userspace using normal
non-cacheable mappings.
(Clint Sbisa)
* for-next/pci:
  arm64: Enable PCI write-combine resources under sysfs

Perf/PMU driver updates.
(Julien Thierry and others)
* for-next/perf:
  perf: arm-cmn: Fix conversion specifiers for node type
  perf: arm-cmn: Fix unsigned comparison to less than zero
  arm_pmu: arm64: Use NMIs for PMU
  arm_pmu: Introduce pmu_irq_ops
  KVM: arm64: pmu: Make overflow handler NMI safe
  arm64: perf: Defer irq_work to IPI_IRQ_WORK
  arm64: perf: Remove PMU locking
  arm64: perf: Avoid PMXEV* indirection
  arm64: perf: Add missing ISB in armv8pmu_enable_counter()
  perf: Add Arm CMN-600 PMU driver
  perf: Add Arm CMN-600 DT binding
  arm64: perf: Add support caps under sysfs
  drivers/perf: thunderx2_pmu: Fix memory resource error handling
  drivers/perf: xgene_pmu: Fix uninitialized resource struct
  perf: arm_dsu: Support DSU ACPI devices
  arm64: perf: Remove unnecessary event_idx check
  drivers/perf: hisi: Add missing include of linux/module.h
  arm64: perf: Add general hardware LLC events for PMUv3

Support for the Armv8.3 Pointer Authentication enhancements.
(By Amit Daniel Kachhap)
* for-next/ptrauth:
  arm64: kprobe: clarify the comment of steppable hint instructions
  arm64: kprobe: disable probe of fault prone ptrauth instruction
  arm64: cpufeature: Modify address authentication cpufeature to exact
  arm64: ptrauth: Introduce Armv8.3 pointer authentication enhancements
  arm64: traps: Allow force_signal_inject to pass esr error code
  arm64: kprobe: add checks for ARMv8.3-PAuth combined instructions

Tonnes of cleanup to the SDEI driver.
(Gavin Shan)
* for-next/sdei:
  firmware: arm_sdei: Remove _sdei_event_unregister()
  firmware: arm_sdei: Remove _sdei_event_register()
  firmware: arm_sdei: Introduce sdei_do_local_call()
  firmware: arm_sdei: Cleanup on cross call function
  firmware: arm_sdei: Remove while loop in sdei_event_unregister()
  firmware: arm_sdei: Remove while loop in sdei_event_register()
  firmware: arm_sdei: Remove redundant error message in sdei_probe()
  firmware: arm_sdei: Remove duplicate check in sdei_get_conduit()
  firmware: arm_sdei: Unregister driver on error in sdei_init()
  firmware: arm_sdei: Avoid nested statements in sdei_init()
  firmware: arm_sdei: Retrieve event number from event instance
  firmware: arm_sdei: Common block for failing path in sdei_event_create()
  firmware: arm_sdei: Remove sdei_is_err()

Selftests for Pointer Authentication and FPSIMD/SVE context-switching.
(Mark Brown and Boyan Karatotev)
* for-next/selftests:
  selftests: arm64: Add build and documentation for FP tests
  selftests: arm64: Add wrapper scripts for stress tests
  selftests: arm64: Add utility to set SVE vector lengths
  selftests: arm64: Add stress tests for FPSMID and SVE context switching
  selftests: arm64: Add test for the SVE ptrace interface
  selftests: arm64: Test case for enumeration of SVE vector lengths
  kselftests/arm64: add PAuth tests for single threaded consistency and differently initialized keys
  kselftests/arm64: add PAuth test for whether exec() changes keys
  kselftests/arm64: add nop checks for PAuth tests
  kselftests/arm64: add a basic Pointer Authentication test

Implementation of ARCH_STACKWALK for unwinding.
(Mark Brown)
* for-next/stacktrace:
  arm64: Move console stack display code to stacktrace.c
  arm64: stacktrace: Convert to ARCH_STACKWALK
  arm64: stacktrace: Make stack walk callback consistent with generic code
  stacktrace: Remove reliable argument from arch_stack_walk() callback

Support for ASID pinning, which is required when sharing page-tables with
the SMMU.
(Jean-Philippe Brucker)
* for-next/svm:
  arm64: cpufeature: Export symbol read_sanitised_ftr_reg()
  arm64: mm: Pin down ASIDs for sharing mm with devices

Rely on firmware tables for establishing CPU topology.
(Valentin Schneider)
* for-next/topology:
  arm64: topology: Stop using MPIDR for topology information

Spelling fixes.
(Xiaoming Ni and Yanfei Xu)
* for-next/tpyos:
  arm64/numa: Fix a typo in comment of arm64_numa_init
  arm64: fix some spelling mistakes in the comments by codespell

vDSO cleanups.
(Will Deacon)
* for-next/vdso:
  arm64: vdso: Fix unusual formatting in *setup_additional_pages()
  arm64: vdso32: Remove a bunch of #ifdef CONFIG_COMPAT_VDSO guards
2020-10-02 12:01:41 +01:00
Julien Grall
f186a84d8a arm64/fpsimd: Update documentation of do_sve_acc
fpsimd_restore_current_state() enables and disables the SVE access trap
based on TIF_SVE, not task_fpsimd_load(). Update the documentation of
do_sve_acc to reflect this behavior.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20200828181155.17745-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2020-09-21 18:06:32 +01:00
Tian Tao
c6b90d5cf6 arm64/fpsimd: Fix missing-prototypes in fpsimd.c
Fix the following warnings.
arch/arm64/kernel/fpsimd.c:935:6: warning: no previous prototype for
‘do_sve_acc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:962:6: warning: no previous prototype for
‘do_fpsimd_acc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:971:6: warning: no previous prototype for
‘do_fpsimd_exc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:1266:6: warning: no previous prototype for
‘kernel_neon_begin’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:1292:6: warning: no previous prototype for
‘kernel_neon_end’ [-Wmissing-prototypes]

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/1600157999-14802-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Will Deacon <will@kernel.org>
2020-09-18 14:33:03 +01:00
Amit Daniel Kachhap
4ef333b2d1 arm64: traps: Allow force_signal_inject to pass esr error code
Some error signal need to pass proper ARM esr error code to userspace to
better identify the cause of the signal. So the function
force_signal_inject is extended to pass this as a parameter. The
existing code is not affected by this change.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20200914083656.21428-3-amit.kachhap@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2020-09-14 12:07:02 +01:00
Will Deacon
e575fb9e76 arm64: sve: Fix build failure when ARM64_SVE=y and SYSCTL=n
When I squashed the 'allnoconfig' compiler warning about the
set_sve_default_vl() function being defined but not used in commit
1e570f512c ("arm64/sve: Eliminate data races on sve_default_vl"), I
accidentally broke the build for configs where ARM64_SVE is enabled, but
SYSCTL is not.

Fix this by only compiling the SVE sysctl support if both CONFIG_SVE=y
and CONFIG_SYSCTL=y.

Cc: Dave Martin <Dave.Martin@arm.com>
Reported-by: Qian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/20200616131808.GA1040@lca.pw
Signed-off-by: Will Deacon <will@kernel.org>
2020-06-16 18:29:11 +01:00
Dave Martin
1e570f512c arm64/sve: Eliminate data races on sve_default_vl
sve_default_vl can be modified via the /proc/sys/abi/sve_default_vl
sysctl concurrently with use, and modified concurrently by multiple
threads.

Adding a lock for this seems overkill, and I don't want to think any
more than necessary, so just define wrappers using READ_ONCE()/
WRITE_ONCE().

This will avoid the possibility of torn accesses and repeated loads
and stores.

There's no evidence yet that this is going wrong in practice: this
is just hygiene.  For generic sysctl users, it would be better to
build this kind of thing into the sysctl common code somehow.

Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/1591808590-20210-3-git-send-email-Dave.Martin@arm.com
[will: move set_sve_default_vl() inside #ifdef to squash allnoconfig warning]
Signed-off-by: Will Deacon <will@kernel.org>
2020-06-15 16:57:42 +01:00
Christoph Hellwig
32927393dc sysctl: pass kernel pointers to ->proc_handler
Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-04-27 02:07:40 -04:00
Suzuki K Poulose
52f73c383b arm64: nofpsmid: Handle TIF_FOREIGN_FPSTATE flag cleanly
We detect the absence of FP/SIMD after an incapable CPU is brought up,
and by then we have kernel threads running already with TIF_FOREIGN_FPSTATE set
which could be set for early userspace applications (e.g, modprobe triggered
from initramfs) and init. This could cause the applications to loop forever in
do_nofity_resume() as we never clear the TIF flag, once we now know that
we don't support FP.

Fix this by making sure that we clear the TIF_FOREIGN_FPSTATE flag
for tasks which may have them set, as we would have done in the normal
case, but avoiding touching the hardware state (since we don't support any).

Also to make sure we handle the cases seemlessly we categorise the
helper functions to two :
 1) Helpers for common core code, which calls into take appropriate
    actions without knowing the current FPSIMD state of the CPU/task.

    e.g fpsimd_restore_current_state(), fpsimd_flush_task_state(),
        fpsimd_save_and_flush_cpu_state().

    We bail out early for these functions, taking any appropriate actions
    (e.g, clearing the TIF flag) where necessary to hide the handling
    from core code.

 2) Helpers used when the presence of FP/SIMD is apparent.
    i.e, save/restore the FP/SIMD register state, modify the CPU/task
    FP/SIMD state.
    e.g,

    fpsimd_save(), task_fpsimd_load() - save/restore task FP/SIMD registers

    fpsimd_bind_task_to_cpu()  \
                                - Update the "state" metadata for CPU/task.
    fpsimd_bind_state_to_cpu() /

    fpsimd_update_current_state() - Update the fp/simd state for the current
                                    task from memory.

    These must not be called in the absence of FP/SIMD. Put in a WARNING
    to make sure they are not invoked in the absence of FP/SIMD.

KVM also uses the TIF_FOREIGN_FPSTATE flag to manage the FP/SIMD state
on the CPU. However, without FP/SIMD support we trap all accesses and
inject undefined instruction. Thus we should never "load" guest state.
Add a sanity check to make sure this is valid.

Fixes: 82e0191a1a ("arm64: Support systems without FP/ASIMD")
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
2020-01-14 17:11:53 +00:00
James Morse
afa7c0e5b9 arm64: Remove asmlinkage from updated functions
Now that the callers of these functions have moved into C, they no longer
need the asmlinkage annotation. Remove it.

Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2019-10-28 11:22:51 +00:00
Dave Martin
ed2f3e9ff6 arm64/sve: Fix a couple of magic numbers for the Z-reg count
There are some hand-written instances of "32" to express the number
of SVE Z-registers.

Since this code was written a #define was added for this, so
convert trivial instances of this magic number as appropriate.

No functional change.

Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
2019-07-22 11:49:03 +01:00
Dave Martin
d16af870a7 arm64/sve: Factor out FPSIMD to SVE state conversion
Currently we convert from FPSIMD to SVE register state in memory in
two places.

To ease future maintenance, let's consolidate this in one place.

Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
2019-07-22 11:48:11 +01:00
Linus Torvalds
dfd437a257 arm64 updates for 5.3:
- arm64 support for syscall emulation via PTRACE_SYSEMU{,_SINGLESTEP}
 
 - Wire up VM_FLUSH_RESET_PERMS for arm64, allowing the core code to
   manage the permissions of executable vmalloc regions more strictly
 
 - Slight performance improvement by keeping softirqs enabled while
   touching the FPSIMD/SVE state (kernel_neon_begin/end)
 
 - Expose a couple of ARMv8.5 features to user (HWCAP): CondM (new XAFLAG
   and AXFLAG instructions for floating point comparison flags
   manipulation) and FRINT (rounding floating point numbers to integers)
 
 - Re-instate ARM64_PSEUDO_NMI support which was previously marked as
   BROKEN due to some bugs (now fixed)
 
 - Improve parking of stopped CPUs and implement an arm64-specific
   panic_smp_self_stop() to avoid warning on not being able to stop
   secondary CPUs during panic
 
 - perf: enable the ARM Statistical Profiling Extensions (SPE) on ACPI
   platforms
 
 - perf: DDR performance monitor support for iMX8QXP
 
 - cache_line_size() can now be set from DT or ACPI/PPTT if provided to
   cope with a system cache info not exposed via the CPUID registers
 
 - Avoid warning on hardware cache line size greater than
   ARCH_DMA_MINALIGN if the system is fully coherent
 
 - arm64 do_page_fault() and hugetlb cleanups
 
 - Refactor set_pte_at() to avoid redundant READ_ONCE(*ptep)
 
 - Ignore ACPI 5.1 FADTs reported as 5.0 (infer from the 'arm_boot_flags'
   introduced in 5.1)
 
 - CONFIG_RANDOMIZE_BASE now enabled in defconfig
 
 - Allow the selection of ARM64_MODULE_PLTS, currently only done via
   RANDOMIZE_BASE (and an erratum workaround), allowing modules to spill
   over into the vmalloc area
 
 - Make ZONE_DMA32 configurable
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:

 - arm64 support for syscall emulation via PTRACE_SYSEMU{,_SINGLESTEP}

 - Wire up VM_FLUSH_RESET_PERMS for arm64, allowing the core code to
   manage the permissions of executable vmalloc regions more strictly

 - Slight performance improvement by keeping softirqs enabled while
   touching the FPSIMD/SVE state (kernel_neon_begin/end)

 - Expose a couple of ARMv8.5 features to user (HWCAP): CondM (new
   XAFLAG and AXFLAG instructions for floating point comparison flags
   manipulation) and FRINT (rounding floating point numbers to integers)

 - Re-instate ARM64_PSEUDO_NMI support which was previously marked as
   BROKEN due to some bugs (now fixed)

 - Improve parking of stopped CPUs and implement an arm64-specific
   panic_smp_self_stop() to avoid warning on not being able to stop
   secondary CPUs during panic

 - perf: enable the ARM Statistical Profiling Extensions (SPE) on ACPI
   platforms

 - perf: DDR performance monitor support for iMX8QXP

 - cache_line_size() can now be set from DT or ACPI/PPTT if provided to
   cope with a system cache info not exposed via the CPUID registers

 - Avoid warning on hardware cache line size greater than
   ARCH_DMA_MINALIGN if the system is fully coherent

 - arm64 do_page_fault() and hugetlb cleanups

 - Refactor set_pte_at() to avoid redundant READ_ONCE(*ptep)

 - Ignore ACPI 5.1 FADTs reported as 5.0 (infer from the
   'arm_boot_flags' introduced in 5.1)

 - CONFIG_RANDOMIZE_BASE now enabled in defconfig

 - Allow the selection of ARM64_MODULE_PLTS, currently only done via
   RANDOMIZE_BASE (and an erratum workaround), allowing modules to spill
   over into the vmalloc area

 - Make ZONE_DMA32 configurable

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (54 commits)
  perf: arm_spe: Enable ACPI/Platform automatic module loading
  arm_pmu: acpi: spe: Add initial MADT/SPE probing
  ACPI/PPTT: Add function to return ACPI 6.3 Identical tokens
  ACPI/PPTT: Modify node flag detection to find last IDENTICAL
  x86/entry: Simplify _TIF_SYSCALL_EMU handling
  arm64: rename dump_instr as dump_kernel_instr
  arm64/mm: Drop [PTE|PMD]_TYPE_FAULT
  arm64: Implement panic_smp_self_stop()
  arm64: Improve parking of stopped CPUs
  arm64: Expose FRINT capabilities to userspace
  arm64: Expose ARMv8.5 CondM capability to userspace
  arm64: defconfig: enable CONFIG_RANDOMIZE_BASE
  arm64: ARM64_MODULES_PLTS must depend on MODULES
  arm64: bpf: do not allocate executable memory
  arm64/kprobes: set VM_FLUSH_RESET_PERMS on kprobe instruction pages
  arm64/mm: wire up CONFIG_ARCH_HAS_SET_DIRECT_MAP
  arm64: module: create module allocations without exec permissions
  arm64: Allow user selection of ARM64_MODULE_PLTS
  acpi/arm64: ignore 5.1 FADTs that are reported as 5.0
  arm64: Allow selecting Pseudo-NMI again
  ...
2019-07-08 09:54:55 -07:00
Thomas Gleixner
caab277b1d treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not see http www gnu org
  licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 503 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:07 +02:00
Dave Martin
41040cf7c5 arm64/sve: Fix missing SVE/FPSIMD endianness conversions
The in-memory representation of SVE and FPSIMD registers is
different: the FPSIMD V-registers are stored as single 128-bit
host-endian values, whereas SVE registers are stored in an
endianness-invariant byte order.

This means that the two representations differ when running on a
big-endian host.  But we blindly copy data from one representation
to another when converting between the two, resulting in the
register contents being unintentionally byteswapped in certain
situations.  Currently this can be triggered by the first SVE
instruction after a syscall, for example (though the potential
trigger points may vary in future).

So, fix the conversion functions fpsimd_to_sve(), sve_to_fpsimd()
and sve_sync_from_fpsimd_zeropad() to swab where appropriate.

There is no common swahl128() or swab128() that we could use here.
Maybe it would be worth making this generic, but for now add a
simple local hack.

Since the byte order differences are exposed in ABI, also clarify
the documentation.

Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Alan Hayward <alan.hayward@arm.com>
Cc: Julien Grall <julien.grall@arm.com>
Fixes: bc0ee47603 ("arm64/sve: Core task context handling")
Fixes: 8cd969d28f ("arm64/sve: Signal handling support")
Fixes: 43d4da2c45 ("arm64/sve: ptrace and ELF coredump support")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
[will: Fix typos in comments and docs spotted by Julien]
Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-06-13 10:07:19 +01:00
Julien Grall
6dcdefcde4 arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state
When the kernel is compiled with CONFIG_KERNEL_MODE_NEON, some part of
the kernel may be able to use FPSIMD/SVE. This is for instance the case
for crypto code.

Any use of FPSIMD/SVE in the kernel are clearly marked by using the
function kernel_neon_{begin, end}. Furthermore, this can only be used
when may_use_simd() returns true.

The current implementation of may_use_simd() allows softirq to use
FPSIMD/SVE unless it is currently in use (i.e kernel_neon_busy is true).
When in use, softirqs usually fall back to a software method.

At the moment, as a softirq may use FPSIMD/SVE, softirqs are disabled
when touching the FPSIMD/SVE context. This has the drawback to disable
all softirqs even if they are not using FPSIMD/SVE.

Since a softirq is supposed to check may_use_simd() anyway before
attempting to use FPSIMD/SVE, there is limited reason to keep softirq
disabled when touching the FPSIMD/SVE context. Instead, we can simply
disable preemption and mark the FPSIMD/SVE context as in use by setting
CPU's fpsimd_context_busy flag.

Two new helpers {get, put}_cpu_fpsimd_context are introduced to mark
the area using FPSIMD/SVE context and they are used to replace
local_bh_{disable, enable}. The functions kernel_neon_{begin, end} are
also re-implemented to use the new helpers.

Additionally, double-underscored versions of the helpers are provided to
called when preemption is already disabled. These are only relevant on
paths where irqs are disabled anyway, so they are not needed for
correctness in the current code. Let's use them anyway though: this
marks critical sections clearly and will help to avoid mistakes during
future maintenance.

The change has been benchmarked on Linux 5.1-rc4 with defconfig.

On Juno2:
    * hackbench 100 process 1000 (10 times)
    * .7% quicker

On ThunderX 2:
    * hackbench 1000 process 1000 (20 times)
    * 3.4% quicker

Reviewed-by: Dave Martin <dave.martin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2019-06-04 13:17:37 +01:00
Julien Grall
54b8c7cbc5 arm64/fpsimd: Introduce fpsimd_save_and_flush_cpu_state() and use it
The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is
the KVM FPSIMD code.

A following patch will introduce a mechanism to acquire owernship of the
FPSIMD/SVE context for performing context management operations. Rather
than having to export the new helpers to get/put the context, we can just
introduce a new function to combine fpsimd_save() and
fpsimd_flush_cpu_state().

This has also the advantage to remove any external call of fpsimd_save()
and fpsimd_flush_cpu_state(), so they can be turned static.

Lastly, the new function can also be used in the PM notifier.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2019-06-04 13:17:30 +01:00
Linus Torvalds
0ef0fd3515 * ARM: support for SVE and Pointer Authentication in guests, PMU improvements
* POWER: support for direct access to the POWER9 XIVE interrupt controller,
 memory and performance optimizations.
 
 * x86: support for accessing memory not backed by struct page, fixes and refactoring
 
 * Generic: dirty page tracking improvements
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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:
   - support for SVE and Pointer Authentication in guests
   - PMU improvements

  POWER:
   - support for direct access to the POWER9 XIVE interrupt controller
   - memory and performance optimizations

  x86:
   - support for accessing memory not backed by struct page
   - fixes and refactoring

  Generic:
   - dirty page tracking improvements"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (155 commits)
  kvm: fix compilation on aarch64
  Revert "KVM: nVMX: Expose RDPMC-exiting only when guest supports PMU"
  kvm: x86: Fix L1TF mitigation for shadow MMU
  KVM: nVMX: Disable intercept for FS/GS base MSRs in vmcs02 when possible
  KVM: PPC: Book3S: Remove useless checks in 'release' method of KVM device
  KVM: PPC: Book3S HV: XIVE: Fix spelling mistake "acessing" -> "accessing"
  KVM: PPC: Book3S HV: Make sure to load LPID for radix VCPUs
  kvm: nVMX: Set nested_run_pending in vmx_set_nested_state after checks complete
  tests: kvm: Add tests for KVM_SET_NESTED_STATE
  KVM: nVMX: KVM_SET_NESTED_STATE - Tear down old EVMCS state before setting new state
  tests: kvm: Add tests for KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_CPU_ID
  tests: kvm: Add tests to .gitignore
  KVM: Introduce KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
  KVM: Fix kvm_clear_dirty_log_protect off-by-(minus-)one
  KVM: Fix the bitmap range to copy during clear dirty
  KVM: arm64: Fix ptrauth ID register masking logic
  KVM: x86: use direct accessors for RIP and RSP
  KVM: VMX: Use accessors for GPRs outside of dedicated caching logic
  KVM: x86: Omit caching logic for always-available GPRs
  kvm, x86: Properly check whether a pfn is an MMIO or not
  ...
2019-05-17 10:33:30 -07:00
Dave Martin
624835abf9 arm64/sve: Clarify vq map semantics
Currently the meanings of sve_vq_map and the ancillary helpers
__bit_to_vq() and __vq_to_bit() are not clearly explained.

This patch makes the explanatory comment clearer, and removes the
duplicate comment from fpsimd.h.

The WARN_ON() currently present in __bit_to_vq() confuses the
intended use of this helper.  Since these are low-level helpers not
intended for general-purpose use anyway, it is better not to make
guesses about how these functions will be used: rather, this patch
removes the WARN_ON() and relies on callers to use the helpers
sensibly.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-04-18 17:14:01 +01:00
Andrew Murray
aaba098fe6 arm64: HWCAP: add support for AT_HWCAP2
As we will exhaust the first 32 bits of AT_HWCAP let's start
exposing AT_HWCAP2 to userspace to give us up to 64 caps.

Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we
prefer to expand into AT_HWCAP2 in order to provide a consistent
view to userspace between ILP32 and LP64. However internal to the
kernel we prefer to continue to use the full space of elf_hwcap.

To reduce complexity and allow for future expansion, we now
represent hwcaps in the kernel as ordinals and use a
KERNEL_HWCAP_ prefix. This allows us to support automatic feature
based module loading for all our hwcaps.

We introduce cpu_set_feature to set hwcaps which complements the
existing cpu_have_feature helper. These helpers allow us to clean
up existing direct uses of elf_hwcap and reduce any future effort
required to move beyond 64 caps.

For convenience we also introduce cpu_{have,set}_named_feature which
makes use of the cpu_feature macro to allow providing a hwcap name
without a {KERNEL_}HWCAP_ prefix.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
[will: use const_ilog2() and tweak documentation]
Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-16 16:27:12 +01:00
Dave Martin
ead9e430c0 arm64/sve: In-kernel vector length availability query interface
KVM will need to interrogate the set of SVE vector lengths
available on the system.

This patch exposes the relevant bits to the kernel, along with a
sve_vq_available() helper to check whether a particular vector
length is supported.

__vq_to_bit() and __bit_to_vq() are not intended for use outside
these functions: now that these are exposed outside fpsimd.c, they
are prefixed with __ in order to provide an extra hint that they
are not intended for general-purpose use.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-03-29 14:41:54 +00:00
Dave Martin
0495067420 arm64/sve: Enable SVE state tracking for non-task contexts
The current FPSIMD/SVE context handling support for non-task (i.e.,
KVM vcpu) contexts does not take SVE into account.  This means that
only task contexts can safely use SVE at present.

In preparation for enabling KVM guests to use SVE, it is necessary
to keep track of SVE state for non-task contexts too.

This patch adds the necessary support, removing assumptions from
the context switch code about the location of the SVE context
storage.

When binding a vcpu context, its vector length is arbitrarily
specified as SVE_VL_MIN for now.  In any case, because TIF_SVE is
presently cleared at vcpu context bind time, the specified vector
length will not be used for anything yet.  In later patches TIF_SVE
will be set here as appropriate, and the appropriate maximum vector
length for the vcpu will be passed when binding.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-03-29 14:41:52 +00:00
Dave Martin
d06b76be8d arm64/sve: Check SVE virtualisability
Due to the way the effective SVE vector length is controlled and
trapped at different exception levels, certain mismatches in the
sets of vector lengths supported by different physical CPUs in the
system may prevent straightforward virtualisation of SVE at parity
with the host.

This patch analyses the extent to which SVE can be virtualised
safely without interfering with migration of vcpus between physical
CPUs, and rejects late secondary CPUs that would erode the
situation further.

It is left up to KVM to decide what to do with this information.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-03-29 14:41:52 +00:00
Dave Martin
8b08e8401f arm64/sve: Clarify role of the VQ map maintenance functions
The roles of sve_init_vq_map(), sve_update_vq_map() and
sve_verify_vq_map() are highly non-obvious to anyone who has not dug
through cpufeatures.c in detail.

Since the way these functions interact with each other is more
important here than a full understanding of the cpufeatures code, this
patch adds comments to make the functions' roles clearer.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-03-29 14:41:52 +00:00
Dave Martin
efbc20249f arm64: fpsimd: Always set TIF_FOREIGN_FPSTATE on task state flush
This patch updates fpsimd_flush_task_state() to mirror the new
semantics of fpsimd_flush_cpu_state() introduced by commit
d8ad71fa38 ("arm64: fpsimd: Fix TIF_FOREIGN_FPSTATE after
invalidating cpu regs").  Both functions now implicitly set
TIF_FOREIGN_FPSTATE to indicate that the task's FPSIMD state is not
loaded into the cpu.

As a side-effect, fpsimd_flush_task_state() now sets
TIF_FOREIGN_FPSTATE even for non-running tasks.  In the case of
non-running tasks this is not useful but also harmless, because the
flag is live only while the corresponding task is running.  This
function is not called from fast paths, so special-casing this for
the task == current case is not really worth it.

Compiler barriers previously present in restore_sve_fpsimd_context()
are pulled into fpsimd_flush_task_state() so that it can be safely
called with preemption enabled if necessary.

Explicit calls to set TIF_FOREIGN_FPSTATE that accompany
fpsimd_flush_task_state() calls and are now redundant are removed
as appropriate.

fpsimd_flush_task_state() is used to get exclusive access to the
representation of the task's state via task_struct, for the purpose
of replacing the state.  Thus, the call to this function should
happen before manipulating fpsimd_state or sve_state etc. in
task_struct.  Anomalous cases are reordered appropriately in order
to make the code more consistent, although there should be no
functional difference since these cases are protected by
local_bh_disable() anyway.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-03-29 14:41:52 +00:00
Eric W. Biederman
c852680959 signal/arm64: Use send_sig_fault where appropriate
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-09-27 21:55:23 +02:00
Mark Rutland
f9209e2629 arm64: move sve_user_{enable,disable} to <asm/fpsimd.h>
In subsequent patches, we'll want to make use of sve_user_enable() and
sve_user_disable() outside of kernel/fpsimd.c. Let's move these to
<asm/fpsimd.h> where we can make use of them.

To avoid ifdeffery in sequences like:

if (system_supports_sve() && some_condition)
	sve_user_disable();

... empty stubs are provided when support for SVE is not enabled. Note
that system_supports_sve() contains as IS_ENABLED(CONFIG_ARM64_SVE), so
the sve_user_disable() call should be optimized away entirely when
CONFIG_ARM64_SVE is not selected.

To ensure that this is the case, the stub definitions contain a
BUILD_BUG(), as we do for other stubs for which calls should always be
optimized away when the relevant config option is not selected.

At the same time, the include list of <asm/fpsimd.h> is sorted while
adding <asm/sysreg.h>.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-07-12 14:40:39 +01:00
Mark Rutland
8d370933fa arm64: kill change_cpacr()
Now that we have sysreg_clear_set(), we can use this instead of
change_cpacr().

Note that the order of the set and clear arguments differs between
change_cpacr() and sysreg_clear_set(), so these are flipped as part of
the conversion. Also, sve_user_enable() redundantly clears
CPACR_EL1_ZEN_EL0EN before setting it; this is removed for clarity.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-07-12 14:40:39 +01:00
Linus Torvalds
b357bf6023 Small update for KVM.
* ARM: lazy context-switching of FPSIMD registers on arm64, "split"
 regions for vGIC redistributor
 
 * s390: cleanups for nested, clock handling, crypto, storage keys and
 control register bits
 
 * x86: many bugfixes, implement more Hyper-V super powers,
 implement lapic_timer_advance_ns even when the LAPIC timer
 is emulated using the processor's VMX preemption timer.  Two
 security-related bugfixes at the top of the branch.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM updates from Paolo Bonzini:
 "Small update for KVM:

  ARM:
   - lazy context-switching of FPSIMD registers on arm64
   - "split" regions for vGIC redistributor

  s390:
   - cleanups for nested
   - clock handling
   - crypto
   - storage keys
   - control register bits

  x86:
   - many bugfixes
   - implement more Hyper-V super powers
   - implement lapic_timer_advance_ns even when the LAPIC timer is
     emulated using the processor's VMX preemption timer.
   - two security-related bugfixes at the top of the branch"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (79 commits)
  kvm: fix typo in flag name
  kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor access
  KVM: x86: pass kvm_vcpu to kvm_read_guest_virt and kvm_write_guest_virt_system
  KVM: x86: introduce linear_{read,write}_system
  kvm: nVMX: Enforce cpl=0 for VMX instructions
  kvm: nVMX: Add support for "VMWRITE to any supported field"
  kvm: nVMX: Restrict VMX capability MSR changes
  KVM: VMX: Optimize tscdeadline timer latency
  KVM: docs: nVMX: Remove known limitations as they do not exist now
  KVM: docs: mmu: KVM support exposing SLAT to guests
  kvm: no need to check return value of debugfs_create functions
  kvm: Make VM ioctl do valloc for some archs
  kvm: Change return type to vm_fault_t
  KVM: docs: mmu: Fix link to NPT presentation from KVM Forum 2008
  kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation
  KVM: x86: hyperv: declare KVM_CAP_HYPERV_TLBFLUSH capability
  KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation
  KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation
  KVM: introduce kvm_make_vcpus_request_mask() API
  KVM: x86: hyperv: do rep check for each hypercall separately
  ...
2018-06-12 11:34:04 -07:00
Linus Torvalds
410feb75de arm64 updates for 4.18:
- Spectre v4 mitigation (Speculative Store Bypass Disable) support for
   arm64 using SMC firmware call to set a hardware chicken bit
 
 - ACPI PPTT (Processor Properties Topology Table) parsing support and
   enable the feature for arm64
 
 - Report signal frame size to user via auxv (AT_MINSIGSTKSZ). The
   primary motivation is Scalable Vector Extensions which requires more
   space on the signal frame than the currently defined MINSIGSTKSZ
 
 - ARM perf patches: allow building arm-cci as module, demote dev_warn()
   to dev_dbg() in arm-ccn event_init(), miscellaneous cleanups
 
 - cmpwait() WFE optimisation to avoid some spurious wakeups
 
 - L1_CACHE_BYTES reverted back to 64 (for performance reasons that have
   to do with some network allocations) while keeping ARCH_DMA_MINALIGN
   to 128. cache_line_size() returns the actual hardware Cache Writeback
   Granule
 
 - Turn LSE atomics on by default in Kconfig
 
 - Kernel fault reporting tidying
 
 - Some #include and miscellaneous cleanups
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:
 "Apart from the core arm64 and perf changes, the Spectre v4 mitigation
  touches the arm KVM code and the ACPI PPTT support touches drivers/
  (acpi and cacheinfo). I should have the maintainers' acks in place.

  Summary:

   - Spectre v4 mitigation (Speculative Store Bypass Disable) support
     for arm64 using SMC firmware call to set a hardware chicken bit

   - ACPI PPTT (Processor Properties Topology Table) parsing support and
     enable the feature for arm64

   - Report signal frame size to user via auxv (AT_MINSIGSTKSZ). The
     primary motivation is Scalable Vector Extensions which requires
     more space on the signal frame than the currently defined
     MINSIGSTKSZ

   - ARM perf patches: allow building arm-cci as module, demote
     dev_warn() to dev_dbg() in arm-ccn event_init(), miscellaneous
     cleanups

   - cmpwait() WFE optimisation to avoid some spurious wakeups

   - L1_CACHE_BYTES reverted back to 64 (for performance reasons that
     have to do with some network allocations) while keeping
     ARCH_DMA_MINALIGN to 128. cache_line_size() returns the actual
     hardware Cache Writeback Granule

   - Turn LSE atomics on by default in Kconfig

   - Kernel fault reporting tidying

   - Some #include and miscellaneous cleanups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (53 commits)
  arm64: Fix syscall restarting around signal suppressed by tracer
  arm64: topology: Avoid checking numa mask for scheduler MC selection
  ACPI / PPTT: fix build when CONFIG_ACPI_PPTT is not enabled
  arm64: cpu_errata: include required headers
  arm64: KVM: Move VCPU_WORKAROUND_2_FLAG macros to the top of the file
  arm64: signal: Report signal frame size to userspace via auxv
  arm64/sve: Thin out initialisation sanity-checks for sve_max_vl
  arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID
  arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests
  arm64: KVM: Add ARCH_WORKAROUND_2 support for guests
  arm64: KVM: Add HYP per-cpu accessors
  arm64: ssbd: Add prctl interface for per-thread mitigation
  arm64: ssbd: Introduce thread flag to control userspace mitigation
  arm64: ssbd: Restore mitigation status on CPU resume
  arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation
  arm64: ssbd: Add global mitigation state accessor
  arm64: Add 'ssbd' command-line option
  arm64: Add ARCH_WORKAROUND_2 probing
  arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2
  arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1
  ...
2018-06-08 11:10:58 -07:00
Dave Martin
87c021a814 arm64/sve: Thin out initialisation sanity-checks for sve_max_vl
Now that the kernel SVE support is reasonably mature, it is
excessive to default sve_max_vl to the invalid value -1 and then
sprinkle WARN_ON()s around the place to make sure it has been
initialised before use.  The cpufeatures code already runs pretty
early, and will ensure sve_max_vl gets initialised.

This patch initialises sve_max_vl to something sane that will be
supported by every SVE implementation, and removes most of the
sanity checks.

The checks in find_supported_vector_length() are retained for now.
If anything goes horribly wrong, we are likely to trip a check here
sooner or later.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-06-01 15:53:07 +01:00
Dave Martin
21cdd7fd76 KVM: arm64: Remove eager host SVE state saving
Now that the host SVE context can be saved on demand from Hyp,
there is no longer any need to save this state in advance before
entering the guest.

This patch removes the relevant call to
kvm_fpsimd_flush_cpu_state().

Since the problem that function was intended to solve now no longer
exists, the function and its dependencies are also deleted.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:28:30 +01:00
Dave Martin
9a6e594869 arm64/sve: Move sve_pffr() to fpsimd.h and make inline
In order to make sve_save_state()/sve_load_state() more easily
reusable and to get rid of a potential branch on context switch
critical paths, this patch makes sve_pffr() inline and moves it to
fpsimd.h.

<asm/processor.h> must be included in fpsimd.h in order to make
this work, and this creates an #include cycle that is tricky to
avoid without modifying core code, due to the way the PR_SVE_*()
prctl helpers are included in the core prctl implementation.

Instead of breaking the cycle, this patch defers inclusion of
<asm/fpsimd.h> in <asm/processor.h> until the point where it is
actually needed: i.e., immediately before the prctl definitions.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:28:29 +01:00
Dave Martin
2cf97d46da arm64/sve: Switch sve_pffr() argument from task to thread
sve_pffr(), which is used to derive the base address used for
low-level SVE save/restore routines, currently takes the relevant
task_struct as an argument.

The only accessed fields are actually part of thread_struct, so
this patch changes the argument type accordingly.  This is done in
preparation for moving this function to a header, where we do not
want to have to include <linux/sched.h> due to the consequent
circular #include problems.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:28:29 +01:00
Dave Martin
31dc52b3c8 arm64/sve: Move read_zcr_features() out of cpufeature.h
Having read_zcr_features() inline in cpufeature.h results in that
header requiring #includes which make it hard to include
<asm/fpsimd.h> elsewhere without triggering header inclusion
cycles.

This is not a hot-path function and arguably should not be in
cpufeature.h in the first place, so this patch moves it to
fpsimd.c, compiled conditionally if CONFIG_ARM64_SVE=y.

This allows some SVE-related #includes to be dropped from
cpufeature.h, which will ease future maintenance.

A couple of missing #includes of <asm/fpsimd.h> are exposed by this
change under arch/arm64/.  This patch adds the missing #includes as
necessary.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:28:29 +01:00
Dave Martin
e6b673b741 KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing
This patch refactors KVM to align the host and guest FPSIMD
save/restore logic with each other for arm64.  This reduces the
number of redundant save/restore operations that must occur, and
reduces the common-case IRQ blackout time during guest exit storms
by saving the host state lazily and optimising away the need to
restore the host state before returning to the run loop.

Four hooks are defined in order to enable this:

 * kvm_arch_vcpu_run_map_fp():
   Called on PID change to map necessary bits of current to Hyp.

 * kvm_arch_vcpu_load_fp():
   Set up FP/SIMD for entering the KVM run loop (parse as
   "vcpu_load fp").

 * kvm_arch_vcpu_ctxsync_fp():
   Get FP/SIMD into a safe state for re-enabling interrupts after a
   guest exit back to the run loop.

   For arm64 specifically, this involves updating the host kernel's
   FPSIMD context tracking metadata so that kernel-mode NEON use
   will cause the vcpu's FPSIMD state to be saved back correctly
   into the vcpu struct.  This must be done before re-enabling
   interrupts because kernel-mode NEON may be used by softirqs.

 * kvm_arch_vcpu_put_fp():
   Save guest FP/SIMD state back to memory and dissociate from the
   CPU ("vcpu_put fp").

Also, the arm64 FPSIMD context switch code is updated to enable it
to save back FPSIMD state for a vcpu, not just current.  A few
helpers drive this:

 * fpsimd_bind_state_to_cpu(struct user_fpsimd_state *fp):
   mark this CPU as having context fp (which may belong to a vcpu)
   currently loaded in its registers.  This is the non-task
   equivalent of the static function fpsimd_bind_to_cpu() in
   fpsimd.c.

 * task_fpsimd_save():
   exported to allow KVM to save the guest's FPSIMD state back to
   memory on exit from the run loop.

 * fpsimd_flush_state():
   invalidate any context's FPSIMD state that is currently loaded.
   Used to disassociate the vcpu from the CPU regs on run loop exit.

These changes allow the run loop to enable interrupts (and thus
softirqs that may use kernel-mode NEON) without having to save the
guest's FPSIMD state eagerly.

Some new vcpu_arch fields are added to make all this work.  Because
host FPSIMD state can now be saved back directly into current's
thread_struct as appropriate, host_cpu_context is no longer used
for preserving the FPSIMD state.  However, it is still needed for
preserving other things such as the host's system registers.  To
avoid ABI churn, the redundant storage space in host_cpu_context is
not removed for now.

arch/arm is not addressed by this patch and continues to use its
current save/restore logic.  It could provide implementations of
the helpers later if desired.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:28:28 +01:00
Dave Martin
0cff8e776f arm64/sve: Refactor user SVE trap maintenance for external use
In preparation for optimising the way KVM manages switching the
guest and host FPSIMD state, it is necessary to provide a means for
code outside arch/arm64/kernel/fpsimd.c to restore the user trap
configuration for SVE correctly for the current task.

Rather than requiring external code to duplicate the maintenance
explicitly, this patch moves the trap maintenenace to
fpsimd_bind_to_cpu(), since it is logically part of the work of
associating the current task with the cpu.

Because fpsimd_bind_to_cpu() is rather a cryptic name to publish
alongside fpsimd_bind_state_to_cpu(), the former function is
renamed to fpsimd_bind_task_to_cpu() to make its purpose more
explicit.

This patch makes appropriate changes to ensure that
fpsimd_bind_task_to_cpu() is always called alongside
task_fpsimd_load(), so that the trap maintenance continues to be
done in every situation where it was done prior to this patch.

As a side-effect, the metadata updates done by
fpsimd_bind_task_to_cpu() now change from conditional to
unconditional in the "already bound" case of sigreturn.  This is
harmless, and a couple of extra stores on this slow path will not
impact performance.  I consider this a reasonable price to pay for
a slightly cleaner interface.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:56 +01:00
Dave Martin
df3fb96820 arm64: fpsimd: Eliminate task->mm checks
Currently the FPSIMD handling code uses the condition task->mm ==
NULL as a hint that task has no FPSIMD register context.

The ->mm check is only there to filter out tasks that cannot
possibly have FPSIMD context loaded, for optimisation purposes.
Also, TIF_FOREIGN_FPSTATE must always be checked anyway before
saving FPSIMD context back to memory.  For these reasons, the ->mm
checks are not useful, providing that TIF_FOREIGN_FPSTATE is
maintained in a consistent way for all threads.

The context switch logic is already deliberately optimised to defer
reloads of the regs until ret_to_user (or sigreturn as a special
case), and save them only if they have been previously loaded.
These paths are the only places where the wrong_task and wrong_cpu
conditions can be made false, by calling fpsimd_bind_task_to_cpu().
Kernel threads by definition never reach these paths.  As a result,
the wrong_task and wrong_cpu tests in fpsimd_thread_switch() will
always yield true for kernel threads.

This patch removes the redundant checks and special-case code,
ensuring that TIF_FOREIGN_FPSTATE is set whenever a kernel thread
is scheduled in, and ensures that this flag is set for the init
task.  The fpsimd_flush_task_state() call already present in
copy_thread() ensures the same for any new task.

With TIF_FOREIGN_FPSTATE always set for kernel threads, this patch
ensures that no extra context save work is added for kernel
threads, and eliminates the redundant context saving that may
currently occur for kernel threads that have acquired an mm via
use_mm().

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:55 +01:00
Dave Martin
d179761519 arm64: fpsimd: Generalise context saving for non-task contexts
In preparation for allowing non-task (i.e., KVM vcpu) FPSIMD
contexts to be handled by the fpsimd common code, this patch adapts
task_fpsimd_save() to save back the currently loaded context,
removing the explicit dependency on current.

The relevant storage to write back to in memory is now found by
examining the fpsimd_last_state percpu struct.

fpsimd_save() does nothing unless TIF_FOREIGN_FPSTATE is clear, and
fpsimd_last_state is updated under local_bh_disable() or
local_irq_disable() everywhere that TIF_FOREIGN_FPSTATE is cleared:
thus, fpsimd_save() will write back to the correct storage for the
loaded context.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:55 +01:00
Dave Martin
09d1223a62 arm64: Use update{,_tsk}_thread_flag()
This patch uses the new update_thread_flag() helpers to simplify a
couple of if () set; else clear; constructs.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:54 +01:00
Dave Martin
d8ad71fa38 arm64: fpsimd: Fix TIF_FOREIGN_FPSTATE after invalidating cpu regs
fpsimd_last_state.st is set to NULL as a way of indicating that
current's FPSIMD registers are no longer loaded in the cpu.  In
particular, this is done when the kernel temporarily uses or
clobbers the FPSIMD registers for its own purposes, as in CPU PM or
kernel-mode NEON, resulting in them being populated with garbage
data not belonging to a task.

Commit 17eed27b02 ("arm64/sve: KVM: Prevent guests from using
SVE") factors this operation out as a new helper
fpsimd_flush_cpu_state() to make it clearer what is being done
here, and on SVE systems this helper is now used, via
kvm_fpsimd_flush_cpu_state(), to invalidate the registers after KVM
has run a vcpu.  The reason for this is that KVM does not yet
understand how to restore the full host SVE registers itself after
loading the guest FPSIMD context into them.

This exposes a particular problem: if fpsimd_last_state.st is set
to NULL without also setting TIF_FOREIGN_FPSTATE, the kernel may
continue to think that current's FPSIMD registers are live even
though they have actually been clobbered.

Prior to the aforementioned commit, the only path where
fpsimd_last_state.st is set to NULL without setting
TIF_FOREIGN_FPSTATE is when kernel_neon_begin() is called by a
kernel thread (where current->mm can be NULL).  This does not
matter, because the only harm is that at context-switch time
fpsimd_thread_switch() may unnecessarily save the FPSIMD registers
back to current's thread_struct (even though kernel threads are not
considered to have any FPSIMD context of their own and the
registers will never be reloaded).

Note that although CPU_PM_ENTER lacks the TIF_FOREIGN_FPSTATE
setting, every CPU passing through that path must subsequently pass
through CPU_PM_EXIT before it can re-enter the kernel proper.
CPU_PM_EXIT sets the flag.

The sve_flush_cpu_state() function added by commit 17eed27b02
also lacks the proper maintenance of TIF_FOREIGN_FPSTATE.  This may
cause the bits of a host task's SVE registers that do not alias the
FPSIMD register file to spontaneously appear zeroed if a KVM vcpu
runs in the same task in the meantime.  Although this effect is
hidden by the fact that the non-FPSIMD bits of the SVE registers
are zeroed by a syscall anyway, it is doubtless a bad idea to rely
on these different code paths interacting correctly under future
maintenance.

This patch makes TIF_FOREIGN_FPSTATE an unconditional side-effect
of fpsimd_flush_cpu_state(), and removes the set_thread_flag()
calls that become redundant as a result.  This ensures that
TIF_FOREIGN_FPSTATE cannot remain clear if the FPSIMD state in the
FPSIMD registers is invalid.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:53 +01:00