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Subject[tip:x86/urgent] x86/microcode/intel: Add a helper which gives the microcode revision
Commit-ID:  4167709bbf826512a52ebd6aafda2be104adaec9
Gitweb: http://git.kernel.org/tip/4167709bbf826512a52ebd6aafda2be104adaec9
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 9 Jan 2017 12:41:45 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 9 Jan 2017 23:11:14 +0100

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>

---
arch/x86/include/asm/microcode_intel.h | 15 ++++++++++++
arch/x86/kernel/cpu/intel.c | 11 +++------
arch/x86/kernel/cpu/microcode/intel.c | 43 ++++++++++------------------------
3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/arch/x86/include/asm/microcode_intel.h b/arch/x86/include/asm/microcode_intel.h
index 195becc..e793fc9 100644
--- a/arch/x86/include/asm/microcode_intel.h
+++ b/arch/x86/include/asm/microcode_intel.h
@@ -52,6 +52,21 @@ struct extended_sigtable {

#define exttable_size(et) ((et)->count * EXT_SIGNATURE_SIZE + EXT_HEADER_SIZE)

+static inline u32 intel_get_microcode_revision(void)
+{
+ u32 rev, dummy;
+
+ 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, dummy, rev);
+
+ return rev;
+}
+
#ifdef CONFIG_MICROCODE_INTEL
extern void __init load_ucode_intel_bsp(void);
extern void load_ucode_intel_ap(void);
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 2d49aa9..203f860 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -14,6 +14,7 @@
#include <asm/bugs.h>
#include <asm/cpu.h>
#include <asm/intel-family.h>
+#include <asm/microcode_intel.h>

#ifdef CONFIG_X86_64
#include <linux/topology.h>
@@ -78,14 +79,8 @@ static void early_init_intel(struct cpuinfo_x86 *c)
(c->x86 == 0x6 && c->x86_model >= 0x0e))
set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);

- if (c->x86 >= 6 && !cpu_has(c, X86_FEATURE_IA64)) {
- unsigned lower_word;
-
- wrmsr(MSR_IA32_UCODE_REV, 0, 0);
- /* Required by the SDM */
- native_cpuid_eax(1);
- rdmsr(MSR_IA32_UCODE_REV, lower_word, c->microcode);
- }
+ if (c->x86 >= 6 && !cpu_has(c, X86_FEATURE_IA64))
+ c->microcode = intel_get_microcode_revision();

/*
* Atom erratum AAE44/AAF40/AAG38/AAH41:
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index f79249fab..faec8fa 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;
}
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