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From:   Wei Huang <wei.huang2@amd.com>
To:     linux-kernel@vger.kernel.org
Cc:     bp@suse.de, tony.luck@intel.com, yazen.ghannam@amd.com,
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        linux-edac@vger.kernel.org, x86@kernel.org,
        smita.koralahallichannabasappa@amd.com, wei.huang2@amd.com
Subject: [PATCH V3 1/1] x86/mce/amd: Add PPIN support for AMD MCE
Date:   Sat, 21 Mar 2020 14:38:00 -0500
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Newer AMD CPUs support a feature called protected processor identification
number (PPIN). This feature can be detected via CPUID_Fn80000008_EBX[23].
However CPUID alone is not enough to read the processor serial number.
MSR_AMD_PPIN_CTL also needs to be configured properly. If for any reason
X86_FEATURE_AMD_PPIN[PPIN_EN] can not be turned on, such as disabled in
BIOS, we have to clear the CPU capability bit of X86_FEATURE_AMD_PPIN.

When the X86_FEATURE_AMD_PPIN capability is available, MCE can read the
serial number to keep track the source of MCE errors.

Co-developed-by: Smita Koralahalli Channabasappa <smita.koralahallichannabasappa@amd.com>
Signed-off-by: Smita Koralahalli Channabasappa <smita.koralahallichannabasappa@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Yazen Ghannam <yazen.ghannam@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
---
 arch/x86/include/asm/cpufeatures.h |  1 +
 arch/x86/kernel/cpu/amd.c          | 30 ++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/mce/core.c     |  2 ++
 3 files changed, 33 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index f3327cb56edf..4b263ffb793b 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -299,6 +299,7 @@
 #define X86_FEATURE_AMD_IBRS		(13*32+14) /* "" Indirect Branch Restricted Speculation */
 #define X86_FEATURE_AMD_STIBP		(13*32+15) /* "" Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_AMD_STIBP_ALWAYS_ON	(13*32+17) /* "" Single Thread Indirect Branch Predictors always-on preferred */
+#define X86_FEATURE_AMD_PPIN		(13*32+23) /* Protected Processor Inventory Number */
 #define X86_FEATURE_AMD_SSBD		(13*32+24) /* "" Speculative Store Bypass Disable */
 #define X86_FEATURE_VIRT_SSBD		(13*32+25) /* Virtualized Speculative Store Bypass Disable */
 #define X86_FEATURE_AMD_SSB_NO		(13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 1f875fbe1384..aef06c37d338 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -394,6 +394,35 @@ static void amd_detect_cmp(struct cpuinfo_x86 *c)
 	per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
 }
 
+static void amd_detect_ppin(struct cpuinfo_x86 *c)
+{
+	unsigned long long val;
+
+	if (!cpu_has(c, X86_FEATURE_AMD_PPIN))
+		return;
+
+	/* When PPIN is defined in CPUID, still need to check PPIN_CTL MSR */
+	if (rdmsrl_safe(MSR_AMD_PPIN_CTL, &val))
+		goto clear_ppin;
+
+	/* PPIN is locked in disabled mode, clear feature bit */
+	if ((val & 3UL) == 1UL)
+		goto clear_ppin;
+
+	/* If PPIN is disabled, try to enable it */
+	if (!(val & 2UL)) {
+		wrmsrl_safe(MSR_AMD_PPIN_CTL,  val | 2UL);
+		rdmsrl_safe(MSR_AMD_PPIN_CTL, &val);
+	}
+
+	/* If PPIN_EN bit is 1, return from here; otherwise fall through */
+	if (val & 2UL)
+		return;
+
+clear_ppin:
+	clear_cpu_cap(c, X86_FEATURE_AMD_PPIN);
+}
+
 u16 amd_get_nb_id(int cpu)
 {
 	return per_cpu(cpu_llc_id, cpu);
@@ -941,6 +970,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	amd_detect_cmp(c);
 	amd_get_topology(c);
 	srat_detect_node(c);
+	amd_detect_ppin(c);
 
 	init_amd_cacheinfo(c);
 
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 2c4f949611e4..57347e899575 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -142,6 +142,8 @@ void mce_setup(struct mce *m)
 
 	if (this_cpu_has(X86_FEATURE_INTEL_PPIN))
 		rdmsrl(MSR_PPIN, m->ppin);
+	else if (this_cpu_has(X86_FEATURE_AMD_PPIN))
+		rdmsrl(MSR_AMD_PPIN, m->ppin);
 
 	m->microcode = boot_cpu_data.microcode;
 }
-- 
2.24.1