From f5bc3aef7df46eaaf423d7413ab8833f704ae576 Mon Sep 17 00:00:00 2001 From: Prathyushi Nangia Date: Tue, 9 Dec 2025 10:01:33 -0600 Subject: [PATCH] x86/CPU/AMD: Prevent improper isolation of shared resources in Zen2's op cache commit c21b90f77687075115d989e53a8ec5e2bb427ab1 upstream. Make sure resources are not improperly shared in the op cache and cause instruction corruption this way. Signed-off-by: Prathyushi Nangia Co-developed-by: Borislav Petkov (AMD) Signed-off-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/msr-index.h | 1 + arch/x86/kernel/cpu/amd.c | 3 +++ tools/arch/x86/include/asm/msr-index.h | 3 +++ 3 files changed, 7 insertions(+) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 2dff91cda82e..093d0bac7941 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -580,6 +580,7 @@ /* Zen4 */ #define MSR_ZEN4_BP_CFG 0xc001102e #define MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT 5 +#define MSR_ZEN2_BP_CFG_BUG_FIX_BIT 33 /* Zen 2 */ #define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 5e284ccb3cc9..6c1ada204bcf 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1170,6 +1170,9 @@ static void init_amd_zen2(struct cpuinfo_x86 *c) { init_amd_zen_common(); init_spectral_chicken(c); + + if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) + msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN2_BP_CFG_BUG_FIX_BIT); } static void init_amd_zen3(struct cpuinfo_x86 *c) diff --git a/tools/arch/x86/include/asm/msr-index.h b/tools/arch/x86/include/asm/msr-index.h index 2c0838ee3eac..658570e4959d 100644 --- a/tools/arch/x86/include/asm/msr-index.h +++ b/tools/arch/x86/include/asm/msr-index.h @@ -530,6 +530,9 @@ #define MSR_AMD64_VIRT_SPEC_CTRL 0xc001011f +#define MSR_ZEN4_BP_CFG 0xc001102e +#define MSR_ZEN2_BP_CFG_BUG_FIX_BIT 33 + /* Fam 17h MSRs */ #define MSR_F17H_IRPERF 0xc00000e9