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

commit f454b18e07f518bcd0c05af17a2239138bff52de upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 3a1e43588685094a6b9c140285e1a993caa25613..a10cd3fef9630c847263ac6627d5d61143f732ae 100644 (file)
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -442,6 +442,10 @@
 
 #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 e0c9ede0196a6181bb3e0c123048ca8c2eb3e1e9..96305270c435dd186de401cb733e147b0d20bb0b 100644 (file)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -24,6 +24,7 @@
 
 static const int amd_erratum_383[];
 static const int amd_erratum_400[];
+static const int amd_erratum_1485[];
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum);
 
 /*
@@ -974,6 +975,10 @@ static void init_amd(struct cpuinfo_x86 *c)
        /* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
        if (!cpu_has(c, X86_FEATURE_XENPV))
                set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
+
+       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
@@ -1102,6 +1107,10 @@ static const int amd_erratum_383[] =
        AMD_OSVW_ERRATUM(3, AMD_MODEL_RANGE(0x10, 0, 0, 0xff, 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++;