Commit-ID: f3e2a51f568d9f33370f4e8bb05669a34223241a
Gitweb: http://git.kernel.org/tip/f3e2a51f568d9f33370f4e8bb05669a34223241a
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Mon, 9 Jan 2017 12:41:44 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 9 Jan 2017 23:11:14 +0100
x86/microcode: Use native CPUID to tickle out microcode revision
Intel supplies the microcode revision value in MSR 0x8b
(IA32_BIOS_SIGN_ID) after CPUID(1) has been executed. Execute it each
time before reading that MSR.
It used to do sync_core() which did do CPUID but
c198b121b1a1 ("x86/asm: Rewrite sync_core() to use IRET-to-self")
changed the sync_core() implementation so we better make the microcode
loading case explicit, as the SDM documents it.
Reported-and-tested-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: http://lkml.kernel.org/r/20170109114147.5082-3-bp@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/intel.c | 2 +-
arch/x86/kernel/cpu/microcode/intel.c | 26 +++-----------------------
2 files changed, 4 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index fcd484d..2d49aa9 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -83,7 +83,7 @@ static void early_init_intel(struct cpuinfo_x86 *c)
wrmsr(MSR_IA32_UCODE_REV, 0, 0);
/* Required by the SDM */
- sync_core();
+ native_cpuid_eax(1);
rdmsr(MSR_IA32_UCODE_REV, lower_word, c->microcode);
}
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index b624b54..f79249fab 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -368,26 +368,6 @@ 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];
@@ -413,7 +393,7 @@ 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 */
- cpuid_1();
+ native_cpuid_eax(1);
/* get the current revision from MSR 0x8B */
native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
@@ -613,7 +593,7 @@ 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 */
- cpuid_1();
+ native_cpuid_eax(1);
/* get the current revision from MSR 0x8B */
native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
@@ -825,7 +805,7 @@ static int apply_microcode_intel(int cpu)
wrmsrl(MSR_IA32_UCODE_REV, 0);
/* As documented in the SDM: Do a CPUID 1 here */
- cpuid_1();
+ native_cpuid_eax(1);
/* get the current revision from MSR 0x8B */
rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
--
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