diff options
Diffstat (limited to 'arch/x86/kernel/cpu/microcode/intel.c')
| -rw-r--r-- | arch/x86/kernel/cpu/microcode/intel.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index 54d50c3694d8..b624b54912e1 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -368,6 +368,26 @@ next: return patch; } +static void cpuid_1(void) +{ + /* + * According to the Intel SDM, Volume 3, 9.11.7: + * + * CPUID returns a value in a model specific register in + * addition to its usual register return values. The + * semantics of CPUID cause it to deposit an update ID value + * in the 64-bit model-specific register at address 08BH + * (IA32_BIOS_SIGN_ID). If no update is present in the + * processor, the value in the MSR remains unmodified. + * + * Use native_cpuid -- this code runs very early and we don't + * want to mess with paravirt. + */ + unsigned int eax = 1, ebx, ecx = 0, edx; + + native_cpuid(&eax, &ebx, &ecx, &edx); +} + static int collect_cpu_info_early(struct ucode_cpu_info *uci) { unsigned int val[2]; @@ -393,7 +413,7 @@ static int collect_cpu_info_early(struct ucode_cpu_info *uci) native_wrmsrl(MSR_IA32_UCODE_REV, 0); /* As documented in the SDM: Do a CPUID 1 here */ - sync_core(); + cpuid_1(); /* get the current revision from MSR 0x8B */ native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]); @@ -593,7 +613,7 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early) native_wrmsrl(MSR_IA32_UCODE_REV, 0); /* As documented in the SDM: Do a CPUID 1 here */ - sync_core(); + cpuid_1(); /* get the current revision from MSR 0x8B */ native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]); @@ -805,7 +825,7 @@ static int apply_microcode_intel(int cpu) wrmsrl(MSR_IA32_UCODE_REV, 0); /* As documented in the SDM: Do a CPUID 1 here */ - sync_core(); + cpuid_1(); /* get the current revision from MSR 0x8B */ rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]); |