From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx> Date: Sat, 7 Oct 2023 12:57:02 +0200 Subject: [PATCH] x86/cpu: Fix AMD erratum #1485 on Zen4-based CPUs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Upstream commit f454b18e07f518bcd0c05af17a2239138bff52de. Fix erratum #1485 on Zen4 parts where running with STIBP disabled can cause an #UD exception. The performance impact of the fix is negligible. Reported-by: René Rebe <rene@xxxxxxxxxxxx> Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Tested-by: René Rebe <rene@xxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Link: https://lore.kernel.org/r/D99589F4-BC5D-430B-87B2-72C20370CF57@xxxxxxxxxxxxx --- arch/x86/include/asm/msr-index.h | 4 ++++ arch/x86/kernel/cpu/amd.c | 8 ++++++++ 2 files changed, 12 insertions(+) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index efedd16231ff..2ee7b3e0dcc1 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -446,6 +446,10 @@ #define MSR_AMD64_VIRT_SPEC_CTRL 0xc001011f +/* Zen4 */ +#define MSR_ZEN4_BP_CFG 0xc001102e +#define MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT 5 + /* Fam 17h MSRs */ #define MSR_F17H_IRPERF 0xc00000e9 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 69eb6a804d1d..dc41d4d7836e 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -72,6 +72,10 @@ static const int amd_zenbleed[] = AMD_MODEL_RANGE(0x17, 0x90, 0x0, 0x91, 0xf), AMD_MODEL_RANGE(0x17, 0xa0, 0x0, 0xaf, 0xf)); +static const int amd_erratum_1485[] = + AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x19, 0x10, 0x0, 0x1f, 0xf), + AMD_MODEL_RANGE(0x19, 0x60, 0x0, 0xaf, 0xf)); + static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum) { int osvw_id = *erratum++; @@ -1122,6 +1126,10 @@ static void init_amd(struct cpuinfo_x86 *c) check_null_seg_clears_base(c); zenbleed_check(c); + + if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && + cpu_has_amd_erratum(c, amd_erratum_1485)) + msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT); } #ifdef CONFIG_X86_32 -- 2.42.0.rc0.25.ga82fb66fed25 -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
