--- /dev/null
+From f454b18e07f518bcd0c05af17a2239138bff52de Mon Sep 17 00:00:00 2001
+From: "Borislav Petkov (AMD)" <bp@alien8.de>
+Date: Sat, 7 Oct 2023 12:57:02 +0200
+Subject: 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
+
+From: Borislav Petkov (AMD) <bp@alien8.de>
+
+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>
+---
+ arch/x86/include/asm/msr-index.h | 4 ++++
+ arch/x86/kernel/cpu/amd.c | 9 +++++++++
+ 2 files changed, 13 insertions(+)
+
+--- 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
+
+--- 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
+ /* 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++;