diff options
Diffstat (limited to 'debian/patches/bugfix/x86/retbleed/0034-x86-cpu-amd-Add-Spectral-Chicken.patch')
| -rw-r--r-- | debian/patches/bugfix/x86/retbleed/0034-x86-cpu-amd-Add-Spectral-Chicken.patch | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/debian/patches/bugfix/x86/retbleed/0034-x86-cpu-amd-Add-Spectral-Chicken.patch b/debian/patches/bugfix/x86/retbleed/0034-x86-cpu-amd-Add-Spectral-Chicken.patch new file mode 100644 index 000000000..a1c73d5c9 --- /dev/null +++ b/debian/patches/bugfix/x86/retbleed/0034-x86-cpu-amd-Add-Spectral-Chicken.patch @@ -0,0 +1,109 @@ +From: Peter Zijlstra <peterz@infradead.org> +Date: Tue, 14 Jun 2022 23:16:04 +0200 +Subject: x86/cpu/amd: Add Spectral Chicken +Origin: https://git.kernel.org/linus/d7caac991feeef1b871ee6988fd2c9725df09039 + +Zen2 uarchs have an undocumented, unnamed, MSR that contains a chicken +bit for some speculation behaviour. It needs setting. + +Note: very belatedly AMD released naming; it's now officially called + MSR_AMD64_DE_CFG2 and MSR_AMD64_DE_CFG2_SUPPRESS_NOBR_PRED_BIT + but shall remain the SPECTRAL CHICKEN. + +Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com> +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Signed-off-by: Borislav Petkov <bp@suse.de> +Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> +Signed-off-by: Borislav Petkov <bp@suse.de> +--- + arch/x86/include/asm/msr-index.h | 3 +++ + arch/x86/kernel/cpu/amd.c | 23 ++++++++++++++++++++++- + arch/x86/kernel/cpu/cpu.h | 2 ++ + arch/x86/kernel/cpu/hygon.c | 6 ++++++ + 4 files changed, 33 insertions(+), 1 deletion(-) + +diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h +index 059c7e500ab4..7b411d9a6efb 100644 +--- a/arch/x86/include/asm/msr-index.h ++++ b/arch/x86/include/asm/msr-index.h +@@ -568,6 +568,9 @@ + /* Fam 17h MSRs */ + #define MSR_F17H_IRPERF 0xc00000e9 + ++#define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3 ++#define MSR_ZEN2_SPECTRAL_CHICKEN_BIT BIT_ULL(1) ++ + /* 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 0c0b09796ced..8cf0659c0521 100644 +--- a/arch/x86/kernel/cpu/amd.c ++++ b/arch/x86/kernel/cpu/amd.c +@@ -862,6 +862,26 @@ static void init_amd_bd(struct cpuinfo_x86 *c) + clear_rdrand_cpuid_bit(c); + } + ++void init_spectral_chicken(struct cpuinfo_x86 *c) ++{ ++ u64 value; ++ ++ /* ++ * On Zen2 we offer this chicken (bit) on the altar of Speculation. ++ * ++ * This suppresses speculation from the middle of a basic block, i.e. it ++ * suppresses non-branch predictions. ++ * ++ * We use STIBP as a heuristic to filter out Zen2 from the rest of F17H ++ */ ++ if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && cpu_has(c, X86_FEATURE_AMD_STIBP)) { ++ if (!rdmsrl_safe(MSR_ZEN2_SPECTRAL_CHICKEN, &value)) { ++ value |= MSR_ZEN2_SPECTRAL_CHICKEN_BIT; ++ wrmsrl_safe(MSR_ZEN2_SPECTRAL_CHICKEN, value); ++ } ++ } ++} ++ + static void init_amd_zn(struct cpuinfo_x86 *c) + { + set_cpu_cap(c, X86_FEATURE_ZEN); +@@ -907,7 +927,8 @@ static void init_amd(struct cpuinfo_x86 *c) + case 0x12: init_amd_ln(c); break; + case 0x15: init_amd_bd(c); break; + case 0x16: init_amd_jg(c); break; +- case 0x17: fallthrough; ++ case 0x17: init_spectral_chicken(c); ++ fallthrough; + case 0x19: init_amd_zn(c); break; + } + +diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h +index 2a8e584fc991..7c9b5893c30a 100644 +--- a/arch/x86/kernel/cpu/cpu.h ++++ b/arch/x86/kernel/cpu/cpu.h +@@ -61,6 +61,8 @@ static inline void tsx_init(void) { } + static inline void tsx_ap_init(void) { } + #endif /* CONFIG_CPU_SUP_INTEL */ + ++extern void init_spectral_chicken(struct cpuinfo_x86 *c); ++ + extern void get_cpu_cap(struct cpuinfo_x86 *c); + extern void get_cpu_address_sizes(struct cpuinfo_x86 *c); + extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c); +diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c +index 3fcdda4c1e11..21fd425088fe 100644 +--- a/arch/x86/kernel/cpu/hygon.c ++++ b/arch/x86/kernel/cpu/hygon.c +@@ -302,6 +302,12 @@ static void init_hygon(struct cpuinfo_x86 *c) + /* get apicid instead of initial apic id from cpuid */ + c->apicid = hard_smp_processor_id(); + ++ /* ++ * XXX someone from Hygon needs to confirm this DTRT ++ * ++ init_spectral_chicken(c); ++ */ ++ + set_cpu_cap(c, X86_FEATURE_ZEN); + set_cpu_cap(c, X86_FEATURE_CPB); + |