linux-kernel - [PATCH v3] x86/mce: Add support for PHYSADDRV and PHYSADDRVALIDSUPPORTED bits

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Message-ID: <20251118191731.181269-1-avadhut.naik@amd.com>
Date: Tue, 18 Nov 2025 19:15:03 +0000
From: Avadhut Naik <avadhut.naik@....com>
To: <x86@...nel.org>, <linux-edac@...r.kernel.org>
CC: <bp@...en8.de>, <tony.luck@...el.com>, <yazen.ghannam@....com>,
	<linux-kernel@...r.kernel.org>, <avadnaik@....com>
Subject: [PATCH v3] x86/mce: Add support for PHYSADDRV and PHYSADDRVALIDSUPPORTED bits

Starting with Zen6, AMD's Scalable MCA systems will incorporate two new
bits in MCA_STATUS and MCA_CONFIG MSRs. These bits will indicate if a
valid System Physical Address (SPA) is present in MCA_ADDR.

PhysAddrValidSupported bit (MCA_CONFIG[11]) serves as the architectural
indicator and states if PhysAddrV bit (MCA_STATUS[54]) is Reserved or
if it indicates validity of SPA in MCA_ADDR.

PhysAddrV bit (MCA_STATUS[54]) advertises if MCA_ADDR contains valid
SPA or if it is implementation specific.

Use and prefer MCA_STATUS[PhysAddrV] when checking for a usable address.

Signed-off-by: Avadhut Naik <avadhut.naik@....com>
---
Changes in v2:
1. Modified commit message per feedback received.
2. Refactored and simplified per feedback received.

CHanges in v3:
1. Avoid reading MCA_CONFIG register everytime amd_mce_usable_address()
is called. Instead, just cache the value if PhysAddrValidSupported bit
is set.

Links:
v1: https://lore.kernel.org/all/20250729204801.1044100-1-avadhut.naik@amd.com/
v2: https://lore.kernel.org/all/20251015172452.3649720-1-avadhut.naik@amd.com/
---
 arch/x86/include/asm/mce.h    |  2 ++
 arch/x86/kernel/cpu/mce/amd.c | 16 +++++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 1cfbfff0be3f..2d98886de09a 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -48,6 +48,7 @@
 
 /* AMD-specific bits */
 #define MCI_STATUS_TCC		BIT_ULL(55)  /* Task context corrupt */
+#define MCI_STATUS_PADDRV	BIT_ULL(54)  /* Valid System Physical Address */
 #define MCI_STATUS_SYNDV	BIT_ULL(53)  /* synd reg. valid */
 #define MCI_STATUS_DEFERRED	BIT_ULL(44)  /* uncorrected error, deferred exception */
 #define MCI_STATUS_POISON	BIT_ULL(43)  /* access poisonous data */
@@ -62,6 +63,7 @@
  */
 #define MCI_CONFIG_MCAX		0x1
 #define MCI_CONFIG_FRUTEXT	BIT_ULL(9)
+#define MCI_CONFIG_PADDRV	BIT_ULL(11)
 #define MCI_IPID_MCATYPE	0xFFFF0000
 #define MCI_IPID_HWID		0xFFF
 
diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 53385e6aa230..3f1dda355307 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -87,6 +87,8 @@ struct smca_bank {
 	const struct smca_hwid *hwid;
 	u32 id;			/* Value of MCA_IPID[InstanceId]. */
 	u8 sysfs_id;		/* Value used for sysfs name. */
+	u64 paddrv	:1,	/* Physical Address Valid bit in MCA_CONFIG */
+	    __reserved	:63;
 };
 
 static DEFINE_PER_CPU_READ_MOSTLY(struct smca_bank[MAX_NR_BANKS], smca_banks);
@@ -327,6 +329,9 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
 
 		this_cpu_ptr(mce_banks_array)[bank].lsb_in_status = !!(low & BIT(8));
 
+		if (low & MCI_CONFIG_PADDRV)
+			this_cpu_ptr(smca_banks)[bank].paddrv = 1;
+
 		wrmsr(smca_config, low, high);
 	}
 
@@ -790,9 +795,9 @@ bool amd_mce_is_memory_error(struct mce *m)
 }
 
 /*
- * AMD systems do not have an explicit indicator that the value in MCA_ADDR is
- * a system physical address. Therefore, individual cases need to be detected.
- * Future cases and checks will be added as needed.
+ * Some AMD systems have an explicit indicator that the value in MCA_ADDR is a
+ * system physical address. Individual cases though, need to be detected for
+ * other systems. Future cases will be added as needed.
  *
  * 1) General case
  *	a) Assume address is not usable.
@@ -806,6 +811,8 @@ bool amd_mce_is_memory_error(struct mce *m)
  *	a) Reported in legacy bank 4 with extended error code (XEC) 8.
  *	b) MCA_STATUS[43] is *not* defined as poison in legacy bank 4. Therefore,
  *	   this bit should not be checked.
+ * 4) MCI_STATUS_PADDRVAL is set
+ *	a) Will provide a valid system physical address.
  *
  * NOTE: SMCA UMC memory errors fall into case #1.
  */
@@ -819,6 +826,9 @@ bool amd_mce_usable_address(struct mce *m)
 			return false;
 	}
 
+	if (this_cpu_ptr(smca_banks)[m->bank].paddrv)
+		return m->status & MCI_STATUS_PADDRV;
+
 	/* Check poison bit for all other bank types. */
 	if (m->status & MCI_STATUS_POISON)
 		return true;

base-commit: c2ef745151b21d4dcc4b29a1eabf1096f5ba544b
-- 
2.43.0