diff options
| author |   Stanislav Spassov <stanspas@amazon.de> | 2025-02-18 14:10:45 +0000 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2025-02-21 14:47:26 +0100 |
| commit | 1937e18cc3cf27e2b3ef70e8c161437051ab7608 (patch) | |
| tree | 3e91975f4a0553e72386dcdc60bd2b270e8b7fcd | |
| parent | x86/fpu: Fully optimize out WARN_ON_FPU() (diff) | |
| download | wireguard-linux-1937e18cc3cf27e2b3ef70e8c161437051ab7608.tar.xz wireguard-linux-1937e18cc3cf27e2b3ef70e8c161437051ab7608.zip | |
x86/fpu: Fix guest FPU state buffer allocation size
Ongoing work on an optimization to batch-preallocate vCPU state buffers
for KVM revealed a mismatch between the allocation sizes used in
fpu_alloc_guest_fpstate() and fpstate_realloc(). While the former
allocates a buffer sized to fit the default set of XSAVE features
in UABI form (as per fpu_user_cfg), the latter uses its ksize argument
derived (for the requested set of features) in the same way as the sizes
found in fpu_kernel_cfg, i.e. using the compacted in-kernel
representation.
The correct size to use for guest FPU state should indeed be the
kernel one as seen in fpstate_realloc(). The original issue likely
went unnoticed through a combination of UABI size typically being
larger than or equal to kernel size, and/or both amounting to the
same number of allocated 4K pages.
Fixes: 69f6ed1d14c6 ("x86/fpu: Provide infrastructure for KVM FPU cleanup")
Signed-off-by: Stanislav Spassov <stanspas@amazon.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250218141045.85201-1-stanspas@amazon.de
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 1209c7aebb21..36df548acc40 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -220,7 +220,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu) struct fpstate *fpstate; unsigned int size; - size = fpu_user_cfg.default_size + ALIGN(offsetof(struct fpstate, regs), 64); + size = fpu_kernel_cfg.default_size + ALIGN(offsetof(struct fpstate, regs), 64); fpstate = vzalloc(size); if (!fpstate) return false; |