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| author | Andy Lutomirski <luto@kernel.org> | 2016-12-09 19:24:07 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-12-19 11:54:21 +0100 |
| commit | 484d0e5c7943644cc46e7308a8f9d83be598f2b9 (patch) | |
| tree | fedce8b05aad45a5dc626458b0e649975c43d759 /arch | |
| parent | Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" (diff) | |
| download | linux-484d0e5c7943644cc46e7308a8f9d83be598f2b9.tar.xz linux-484d0e5c7943644cc46e7308a8f9d83be598f2b9.zip | |
x86/microcode/intel: Replace sync_core() with native_cpuid()
The Intel microcode driver is using sync_core() to mean "do CPUID
with EAX=1". I want to rework sync_core(), but first the Intel
microcode driver needs to stop depending on its current behavior.
Reported-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Matthew Whitehead <tedheadster@gmail.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel <Xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/535a025bb91fed1a019c5412b036337ad239e5bb.1481307769.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
| -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]); |