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Subject[PATCH 4.4 179/266] x86/microcode/intel: Add a helper which gives the microcode revision
Date
From: Borislav Petkov <bp@suse.de>

commit 4167709bbf826512a52ebd6aafda2be104adaec9 upstream.

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>
[bwh: Backported to 4.4:
- Don't touch prev_rev variable in apply_microcode()
- Keep using sync_core(), which will alway includes the necessary CPUID
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/microcode_intel.h | 15 ++++++++++++
arch/x86/kernel/cpu/intel.c | 11 ++-------
arch/x86/kernel/cpu/microcode/intel.c | 39 +++++++++------------------------
3 files changed, 29 insertions(+), 36 deletions(-)

--- a/arch/x86/include/asm/microcode_intel.h
+++ b/arch/x86/include/asm/microcode_intel.h
@@ -53,6 +53,21 @@ 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 */
+ sync_core();
+
+ /* get the current revision from MSR 0x8B */
+ native_rdmsr(MSR_IA32_UCODE_REV, dummy, rev);
+
+ return rev;
+}
+
extern int has_newer_microcode(void *mc, unsigned int csig, int cpf, int rev);
extern int microcode_sanity_check(void *mc, int print_err);
extern int find_matching_signature(void *mc, unsigned int csig, int cpf);
--- 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>
@@ -102,14 +103,8 @@ static void early_init_intel(struct cpui
(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 */
- sync_core();
- 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();

/* Now if any of them are set, check the blacklist and clear the lot */
if ((cpu_has(c, X86_FEATURE_SPEC_CTRL) ||
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -376,15 +376,8 @@ static int collect_cpu_info_early(struct
native_rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
csig.pf = 1 << ((val[1] >> 18) & 7);
}
- native_wrmsr(MSR_IA32_UCODE_REV, 0, 0);

- /* As documented in the SDM: Do a CPUID 1 here */
- sync_core();
-
- /* 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;
@@ -654,7 +647,7 @@ static inline void print_ucode(struct uc
static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
{
struct microcode_intel *mc_intel;
- unsigned int val[2];
+ u32 rev;

mc_intel = uci->mc;
if (mc_intel == NULL)
@@ -664,21 +657,16 @@ static int apply_microcode_early(struct
native_wrmsr(MSR_IA32_UCODE_WRITE,
(unsigned long) mc_intel->bits,
(unsigned long) mc_intel->bits >> 16 >> 16);
- native_wrmsr(MSR_IA32_UCODE_REV, 0, 0);

- /* As documented in the SDM: Do a CPUID 1 here */
- sync_core();
-
- /* get the current revision from MSR 0x8B */
- native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
- if (val[1] != mc_intel->hdr.rev)
+ rev = intel_get_microcode_revision();
+ if (rev != mc_intel->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);
@@ -852,7 +840,7 @@ static int apply_microcode_intel(int cpu
{
struct microcode_intel *mc_intel;
struct ucode_cpu_info *uci;
- unsigned int val[2];
+ u32 rev;
int cpu_num = raw_smp_processor_id();
struct cpuinfo_x86 *c = &cpu_data(cpu_num);

@@ -877,27 +865,22 @@ static int apply_microcode_intel(int cpu
wrmsr(MSR_IA32_UCODE_WRITE,
(unsigned long) mc_intel->bits,
(unsigned long) mc_intel->bits >> 16 >> 16);
- wrmsr(MSR_IA32_UCODE_REV, 0, 0);
-
- /* As documented in the SDM: Do a CPUID 1 here */
- sync_core();

- /* 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_intel->hdr.rev) {
+ if (rev != mc_intel->hdr.rev) {
pr_err("CPU%d update to revision 0x%x failed\n",
cpu_num, mc_intel->hdr.rev);
return -1;
}
pr_info("CPU%d updated to revision 0x%x, date = %04x-%02x-%02x\n",
- cpu_num, val[1],
+ cpu_num, rev,
mc_intel->hdr.date & 0xffff,
mc_intel->hdr.date >> 24,
(mc_intel->hdr.date >> 16) & 0xff);

- uci->cpu_sig.rev = val[1];
- c->microcode = val[1];
+ uci->cpu_sig.rev = rev;
+ c->microcode = rev;

return 0;
}

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