x86/microcode/intel: Add a helper which gives the microcode revision

Since on Intel we're required to do CPUID(1) first, before reading
the microcode revision MSR, let's add a special helper which does the
required steps so that we don't forget to do them next time, when we
want to read the microcode revision.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20170109114147.5082-4-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 13 insertions, 30 deletions

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index f79249fab389..faec8fa68ffd 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -390,15 +390,8 @@ static int collect_cpu_info_early(struct ucode_cpu_info *uci)
                 native_rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
                 csig.pf = 1 << ((val[1] >> 18) & 7);
         }
-        native_wrmsrl(MSR_IA32_UCODE_REV, 0);
 
-        /* As documented in the SDM: Do a CPUID 1 here */
-        native_cpuid_eax(1);
-
-        /* get the current revision from MSR 0x8B */
-        native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
-
-        csig.rev = val[1];
+        csig.rev = intel_get_microcode_revision();
 
         uci->cpu_sig = csig;
         uci->valid = 1;
@@ -582,7 +575,7 @@ static inline void print_ucode(struct ucode_cpu_info *uci)
 static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 {
         struct microcode_intel *mc;
-        unsigned int val[2];
+        u32 rev;
 
         mc = uci->mc;
         if (!mc)
@@ -590,21 +583,16 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 
         /* write microcode via MSR 0x79 */
         native_wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc->bits);
-        native_wrmsrl(MSR_IA32_UCODE_REV, 0);
 
-        /* As documented in the SDM: Do a CPUID 1 here */
-        native_cpuid_eax(1);
-
-        /* get the current revision from MSR 0x8B */
-        native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
-        if (val[1] != mc->hdr.rev)
+        rev = intel_get_microcode_revision();
+        if (rev != mc->hdr.rev)
                 return -1;
 
 #ifdef CONFIG_X86_64
         /* Flush global tlb. This is precaution. */
         flush_tlb_early();
 #endif
-        uci->cpu_sig.rev = val[1];
+        uci->cpu_sig.rev = rev;
 
         if (early)
                 print_ucode(uci);
@@ -784,8 +772,8 @@ static int apply_microcode_intel(int cpu)
         struct microcode_intel *mc;
         struct ucode_cpu_info *uci;
         struct cpuinfo_x86 *c;
-        unsigned int val[2];
         static int prev_rev;
+        u32 rev;
 
         /* We should bind the task to the CPU */
         if (WARN_ON(raw_smp_processor_id() != cpu))
@@ -802,33 +790,28 @@ static int apply_microcode_intel(int cpu)
 
         /* write microcode via MSR 0x79 */
         wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc->bits);
-        wrmsrl(MSR_IA32_UCODE_REV, 0);
-
-        /* As documented in the SDM: Do a CPUID 1 here */
-        native_cpuid_eax(1);
 
-        /* get the current revision from MSR 0x8B */
-        rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
+        rev = intel_get_microcode_revision();
 
-        if (val[1] != mc->hdr.rev) {
+        if (rev != mc->hdr.rev) {
                 pr_err("CPU%d update to revision 0x%x failed\n",
                        cpu, mc->hdr.rev);
                 return -1;
         }
 
-        if (val[1] != prev_rev) {
+        if (rev != prev_rev) {
                 pr_info("updated to revision 0x%x, date = %04x-%02x-%02x\n",
-                        val[1],
+                        rev,
                         mc->hdr.date & 0xffff,
                         mc->hdr.date >> 24,
                         (mc->hdr.date >> 16) & 0xff);
-                prev_rev = val[1];
+                prev_rev = rev;
         }
 
         c = &cpu_data(cpu);
 
-        uci->cpu_sig.rev = val[1];
-        c->microcode = val[1];
+        uci->cpu_sig.rev = rev;
+        c->microcode = rev;
 
         return 0;
 }