[MODERATED] [PATCH v2 1/2] v2: more sampling fun 1

From: mark gross <mgross@linux.intel.com>
To: speck@linutronix.de
Subject: [MODERATED] [PATCH v2 1/2] v2: more sampling fun 1
Date: Thu, 6 Feb 2020 14:11:02 -0800	[thread overview]
Message-ID: <=?utf-8?q?=3C0e637bd8b28bb3f53c278b0dee8219c3bdda40db=2E158258?= =?utf-8?q?0710=2Egit=2Emgross=40linux=2Eintel=2Ecom=3E?=> (raw)
In-Reply-To: <cover.1582580710.git.mgross@linux.intel.com>

From: mark gross <mgross@linux.intel.com>
Subject: [PATCH v2 1/2] Add capability to specify a range of steppings in the
 vulnerability white list structure.

From: mark gross <mgross@linux.intel.com>
Subject: [PATCH v2 1/2] Add capability to specify a range of steppings in the

Intel has produced processors with the same CPUID family+model. Code
may need to check the stepping when programming model specific behavior.

Add an API to allow easy specification of stepping or range of steppings
with a 16 bit bitmask.

Update cpu_vuln_whitelist using this new API.

I implemented this in the way I did to avoid modifying x86_cpu_id as
that structure is an exported ABI and any change would impact user mode
code using the structure.

Signed-off-by: mark gross <mgross@linux.intel.com>
Reviewed-by: tony luck <tony.luck@intel.com>
---
 arch/x86/include/asm/cpu_device_id.h | 12 ++++++++++++
 arch/x86/kernel/cpu/common.c         | 28 ++++++++++++++--------------
 arch/x86/kernel/cpu/match.c          | 26 ++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/cpu_device_id.h b/arch/x86/include/asm/cpu_device_id.h
index 31c379c1da41..e9de5f6d784a 100644
--- a/arch/x86/include/asm/cpu_device_id.h
+++ b/arch/x86/include/asm/cpu_device_id.h
@@ -35,7 +35,19 @@ struct x86_cpu_desc {
 	.x86_microcode_rev	= (revision),			\
 }
 
+/*
+ * Match a range of steppings
+ */
+
+struct x86_cpu_id_ext {
+	struct x86_cpu_id id;
+	__u16 steppings; /* bit map of steppings to match against */
+};
+
+#define X86_STEPPING_ANY GENMASK(15,0)
+
 extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
+const struct x86_cpu_id_ext *x86_match_cpu_ext(const struct x86_cpu_id_ext *match);
 extern bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table);
 
 #endif /* _ASM_X86_CPU_DEVICE_ID */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 52c9bfbbdb2a..c0519be5f563 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1008,23 +1008,23 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
 #define NO_ITLB_MULTIHIT	BIT(7)
 #define NO_SPECTRE_V2		BIT(8)
 
-#define VULNWL(_vendor, _family, _model, _whitelist)	\
-	{ X86_VENDOR_##_vendor, _family, _model, X86_FEATURE_ANY, _whitelist }
+#define VULNWL(_vendor, _family, _model, __stepping,  _whitelist)	\
+	{{ X86_VENDOR_##_vendor, _family, _model, X86_FEATURE_ANY, _whitelist }, __stepping}
 
 #define VULNWL_INTEL(model, whitelist)		\
-	VULNWL(INTEL, 6, INTEL_FAM6_##model, whitelist)
+	VULNWL(INTEL, 6, INTEL_FAM6_##model, X86_STEPPING_ANY, whitelist)
 
 #define VULNWL_AMD(family, whitelist)		\
-	VULNWL(AMD, family, X86_MODEL_ANY, whitelist)
+	VULNWL(AMD, family, X86_MODEL_ANY, X86_STEPPING_ANY, whitelist)
 
 #define VULNWL_HYGON(family, whitelist)		\
-	VULNWL(HYGON, family, X86_MODEL_ANY, whitelist)
+	VULNWL(HYGON, family, X86_MODEL_ANY, X86_STEPPING_ANY, whitelist)
 
-static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
-	VULNWL(ANY,	4, X86_MODEL_ANY,	NO_SPECULATION),
-	VULNWL(CENTAUR,	5, X86_MODEL_ANY,	NO_SPECULATION),
-	VULNWL(INTEL,	5, X86_MODEL_ANY,	NO_SPECULATION),
-	VULNWL(NSC,	5, X86_MODEL_ANY,	NO_SPECULATION),
+static const struct x86_cpu_id_ext cpu_vuln_whitelist[] __initconst = {
+	VULNWL(ANY,	4, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECULATION),
+	VULNWL(CENTAUR,	5, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECULATION),
+	VULNWL(INTEL,	5, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECULATION),
+	VULNWL(NSC,	5, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECULATION),
 
 	/* Intel Family 6 */
 	VULNWL_INTEL(ATOM_SALTWELL,		NO_SPECULATION | NO_ITLB_MULTIHIT),
@@ -1070,16 +1070,16 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
 	VULNWL_HYGON(X86_FAMILY_ANY,	NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT),
 
 	/* Zhaoxin Family 7 */
-	VULNWL(CENTAUR,	7, X86_MODEL_ANY,	NO_SPECTRE_V2 | NO_SWAPGS),
-	VULNWL(ZHAOXIN,	7, X86_MODEL_ANY,	NO_SPECTRE_V2 | NO_SWAPGS),
+	VULNWL(CENTAUR,	7, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECTRE_V2 | NO_SWAPGS),
+	VULNWL(ZHAOXIN,	7, X86_MODEL_ANY, X86_STEPPING_ANY,	NO_SPECTRE_V2 | NO_SWAPGS),
 	{}
 };
 
 static bool __init cpu_matches(unsigned long which)
 {
-	const struct x86_cpu_id *m = x86_match_cpu(cpu_vuln_whitelist);
+	const struct x86_cpu_id_ext *m = x86_match_cpu_ext(cpu_vuln_whitelist);
 
-	return m && !!(m->driver_data & which);
+	return m && !!(m->id.driver_data & which);
 }
 
 u64 x86_read_arch_cap_msr(void)
diff --git a/arch/x86/kernel/cpu/match.c b/arch/x86/kernel/cpu/match.c
index 6dd78d8235e4..118c503b1c36 100644
--- a/arch/x86/kernel/cpu/match.c
+++ b/arch/x86/kernel/cpu/match.c
@@ -49,6 +49,32 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
 }
 EXPORT_SYMBOL(x86_match_cpu);
 
+/*
+ * Extend x86_match_cpu to support matching a range of steppings.
+ */
+const struct x86_cpu_id_ext *x86_match_cpu_ext(const struct x86_cpu_id_ext *match)
+{
+	const struct x86_cpu_id_ext *m;
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	for (m = match; m->id.vendor | m->id.family | m->id.model | m->id.feature; m++) {
+		if (m->id.vendor != X86_VENDOR_ANY && c->x86_vendor != m->id.vendor)
+			continue;
+		if (m->id.family != X86_FAMILY_ANY && c->x86 != m->id.family)
+			continue;
+		if (m->id.model != X86_MODEL_ANY && c->x86_model != m->id.model)
+			continue;
+		if (m->steppings != X86_STEPPING_ANY &&
+		    !(BIT(c->x86_stepping) & m->steppings))
+			continue;
+		if (m->id.feature != X86_FEATURE_ANY && !cpu_has(c, m->id.feature))
+			continue;
+		return m;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(x86_match_cpu_ext);
+
 static const struct x86_cpu_desc *
 x86_match_cpu_with_stepping(const struct x86_cpu_desc *match)
 {
-- 
2.17.1
