diff options
| author | Borislav Petkov (AMD) <bp@alien8.de> | 2026-04-07 11:40:03 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-04-17 06:04:42 -0700 |
| commit | e55d98e7756135f32150b9b8f75d580d0d4b2dd3 (patch) | |
| tree | 237ff6781f15dcaf2047a7868a2088b29058312a /arch/x86/kernel | |
| parent | 43cfbdda5af60ffc6272a7b8c5c37d1d0a181ca9 (diff) | |
x86/CPU: Fix FPDSS on Zen1
Zen1's hardware divider can leave, under certain circumstances, partial
results from previous operations. Those results can be leaked by
another, attacker thread.
Fix that with a chicken bit.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 33b740c26bef..2d9ae6ab1701 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -944,6 +944,9 @@ static void init_amd_zen1(struct cpuinfo_x86 *c) msr_clear_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT); clear_cpu_cap(c, X86_FEATURE_IRPERF); } + + pr_notice_once("AMD Zen1 FPDSS bug detected, enabling mitigation.\n"); + msr_set_bit(MSR_AMD64_FP_CFG, MSR_AMD64_FP_CFG_ZEN1_DENORM_FIX_BIT); } static const struct x86_cpu_id amd_zenbleed_microcode[] = { |