[PATCH V6 1/5] x86/cpufeature: Add facility to check for min microcode revisions

kan.liang
2019-01-21T21:43:28Z

From: Kan Liang <kan.liang@linux.intel.com>

For bug workarounds or checks, it is useful to check for specific
microcode revisions.

Add a new generic function to match the CPU with stepping.
Add the other function to check the min microcode revisions for
the matched CPU.
A new table format is introduced to facilitate the quirk to
fill the related information.

This does not change the existing x86_cpu_id because it's an ABI
shared with modules, and also has quite different requirements,
as in no wildcards, but everything has to be matched exactly.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Originally-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---

Changes since V5:
- Use proper tag
- Rename x86_cpu_check to x86_cpu_desc, and rename its members
the same way as the corresponding members in struct cpuinfo_x86
are named.
- Rename INTEL_CHECK_UCODE to INTEL_CPU_DESC
- Use EXPORT_SYMBOL_GPL

arch/x86/include/asm/cpu_device_id.h | 28 ++++++++++++++++++++++++++++
arch/x86/kernel/cpu/match.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)

diff --git a/arch/x86/include/asm/cpu_device_id.h b/arch/x86/include/asm/cpu_device_id.h
index baeba05..f35b303 100644
--- a/arch/x86/include/asm/cpu_device_id.h
+++ b/arch/x86/include/asm/cpu_device_id.h
@@ -11,4 +11,32 @@

extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);

+/*
+ * Match specific microcode revisions.
+ *
+ * vendor/family/model/stepping must be all set.
+ *
+ * only checks against the boot CPU. When mixed-stepping configs are
+ * valid for a CPU model, add a quirk for every valid stepping and
+ * do the fine-tuning in the quirk handler.
+ */
+
+struct x86_cpu_desc {
+ __u8 x86; /* CPU family */
+ __u8 x86_vendor; /* CPU vendor */
+ __u8 x86_model;
+ __u8 x86_stepping;
+ __u32 x86_microcode_rev;
+};
+
+#define INTEL_CPU_DESC(mod, step, rev) { \
+ .x86 = 6, \
+ .x86_vendor = X86_VENDOR_INTEL, \
+ .x86_model = mod, \
+ .x86_stepping = step, \
+ .x86_microcode_rev = rev, \
+}
+
+extern bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table);
+
#endif
diff --git a/arch/x86/kernel/cpu/match.c b/arch/x86/kernel/cpu/match.c
index 3fed388..4f4bf89 100644
--- a/arch/x86/kernel/cpu/match.c
+++ b/arch/x86/kernel/cpu/match.c
@@ -48,3 +48,34 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
return NULL;
}
EXPORT_SYMBOL(x86_match_cpu);
+
+static const struct x86_cpu_desc *
+x86_match_cpu_with_stepping(const struct x86_cpu_desc *match)
+{
+ struct cpuinfo_x86 *c = &boot_cpu_data;
+ const struct x86_cpu_desc *m;
+
+ for (m = match; m->x86 | m->x86_model; m++) {
+ if (c->x86_vendor != m->x86_vendor)
+ continue;
+ if (c->x86 != m->x86)
+ continue;
+ if (c->x86_model != m->x86_model)
+ continue;
+ if (c->x86_stepping != m->x86_stepping)
+ continue;
+ return m;
+ }
+ return NULL;
+}
+
+bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table)
+{
+ const struct x86_cpu_desc *res = x86_match_cpu_with_stepping(table);
+
+ if (!res || res->x86_microcode_rev > boot_cpu_data.microcode)
+ return false;
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(x86_cpu_has_min_microcode_rev);
--
2.7.4