x86/cpu: Fix AMD erratum #1485 on Zen4-based CPUs

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@exactcode.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: René Rebe <rene@exactcode.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/D99589F4-BC5D-430B-87B2-72C20370CF57@exactcode.com

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 1d11135..b37abb5 100644 (file)
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -637,12 +637,17 @@
 /* AMD Last Branch Record MSRs */
 #define MSR_AMD64_LBR_SELECT                   0xc000010e
 
-/* Fam 17h MSRs */
-#define MSR_F17H_IRPERF                        0xc00000e9
+/* Zen4 */
+#define MSR_ZEN4_BP_CFG                        0xc001102e
+#define MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT 5
 
+/* Zen 2 */
 #define MSR_ZEN2_SPECTRAL_CHICKEN      0xc00110e3
 #define MSR_ZEN2_SPECTRAL_CHICKEN_BIT  BIT_ULL(1)
 
+/* Fam 17h MSRs */
+#define MSR_F17H_IRPERF                        0xc00000e9
+
 /* Fam 16h MSRs */
 #define MSR_F16H_L2I_PERF_CTL          0xc0010230
 #define MSR_F16H_L2I_PERF_CTR          0xc0010231

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 03ef962..ece2b5b 100644 (file)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -80,6 +80,10 @@ static const int amd_div0[] =
        AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x17, 0x00, 0x0, 0x2f, 0xf),
                           AMD_MODEL_RANGE(0x17, 0x50, 0x0, 0x5f, 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++;
@@ -1149,6 +1153,10 @@ static void init_amd(struct cpuinfo_x86 *c)
                pr_notice_once("AMD Zen1 DIV0 bug detected. Disable SMT for full protection.\n");
                setup_force_cpu_bug(X86_BUG_DIV0);
        }
+
+       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