diff options
| author | Feng Tang <[email protected]> | 2023-08-23 14:57:47 +0800 |
|---|---|---|
| committer | Thomas Gleixner <[email protected]> | 2023-08-24 11:01:45 +0200 |
| commit | 2c66ca3949dc701da7f4c9407f2140ae425683a5 (patch) | |
| tree | 92810e9e3cdc6fa1a8fcb952000a0b8044806f63 | |
| parent | 1f69383b203e28cf8a4ca9570e572da1699f76cd (diff) | |
x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4
0-Day found a 34.6% regression in stress-ng's 'af-alg' test case, and
bisected it to commit b81fac906a8f ("x86/fpu: Move FPU initialization into
arch_cpu_finalize_init()"), which optimizes the FPU init order, and moves
the CR4_OSXSAVE enabling into a later place:
arch_cpu_finalize_init
identify_boot_cpu
identify_cpu
generic_identify
get_cpu_cap --> setup cpu capability
...
fpu__init_cpu
fpu__init_cpu_xstate
cr4_set_bits(X86_CR4_OSXSAVE);
As the FPU is not yet initialized the CPU capability setup fails to set
X86_FEATURE_OSXSAVE. Many security module like 'camellia_aesni_avx_x86_64'
depend on this feature and therefore fail to load, causing the regression.
Cure this by setting X86_FEATURE_OSXSAVE feature right after OSXSAVE
enabling.
[ tglx: Moved it into the actual BSP FPU initialization code and added a comment ]
Fixes: b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Feng Tang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/lkml/[email protected]
Link: https://lore.kernel.org/lkml/[email protected]
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 0bab497c9436..1afbc4866b10 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -882,6 +882,13 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) goto out_disable; } + /* + * CPU capabilities initialization runs before FPU init. So + * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely + * functional, set the feature bit so depending code works. + */ + setup_force_cpu_cap(X86_FEATURE_OSXSAVE); + print_xstate_offset_size(); pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n", fpu_kernel_cfg.max_features, |