Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
authored by
Borislav Petkov (AMD)
and committed by
Linus Torvalds
e55d98e7
43cfbdda
+6
+3
arch/x86/include/asm/msr-index.h
+3
arch/x86/include/asm/msr-index.h
···
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#define MSR_AMD64_DC_CFG 0xc0011022
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#define MSR_AMD64_TW_CFG 0xc0011023
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+
#define MSR_AMD64_FP_CFG 0xc0011028
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#define MSR_AMD64_FP_CFG_ZEN1_DENORM_FIX_BIT 9
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+
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#define MSR_AMD64_DE_CFG 0xc0011029
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#define MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT 1
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#define MSR_AMD64_DE_CFG_LFENCE_SERIALIZE BIT_ULL(MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT)
+3
arch/x86/kernel/cpu/amd.c
+3
arch/x86/kernel/cpu/amd.c
···
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msr_clear_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT);
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clear_cpu_cap(c, X86_FEATURE_IRPERF);
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}
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+
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pr_notice_once("AMD Zen1 FPDSS bug detected, enabling mitigation.\n");
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msr_set_bit(MSR_AMD64_FP_CFG, MSR_AMD64_FP_CFG_ZEN1_DENORM_FIX_BIT);
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}
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static const struct x86_cpu_id amd_zenbleed_microcode[] = {