[PATCH 6.12.y 4/4] cxl/ras: Fix cxl_rch_get_aer_severity() wrong severity register

[Sasha Levin <sashal@kernel.org>]

From: Terry Bowman <terry.bowman@amd.com>

[ Upstream commit 9d399526128bae184b153deab42b49f5f3eea2ed ]

cxl_rch_get_aer_severity() classifies RCH Downstream Port uncorrectable
errors as fatal or non-fatal by ANDing uncorrectable status with
PCI_ERR_ROOT_FATAL_RCV. This is wrong because PCI_ERR_ROOT_FATAL_RCV is a
Root Error Status register bit (bit 6), not a severity bit. ANDing it
against uncorrectable status tests a reserved bit and produces incorrect
severity classification.

Fix by ANDing the unmasked uncor_status against uncor_severity. Per
PCIe Base Spec r6.0 Section 7.8.4.4, each bit in the Uncorrectable
Error Severity register indicates whether the corresponding error is
fatal (1) or non-fatal (0).

Fixes: 6ac07883dbb5 ("cxl/pci: Add RCH downstream port error logging")
Cc: stable@vger.kernel.org
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20260803221810.3685703-3-terry.bowman@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/cxl/core/ras_rch.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/ras_rch.c b/drivers/cxl/core/ras_rch.c
index ed58afd18ecc9..cc70373d97fc5 100644
--- a/drivers/cxl/core/ras_rch.c
+++ b/drivers/cxl/core/ras_rch.c
@@ -79,11 +79,11 @@ static bool cxl_rch_get_aer_info(void __iomem *aer_base,
 static bool cxl_rch_get_aer_severity(struct aer_capability_regs *aer_regs,
 				     int *severity)
 {
-	if (aer_regs->uncor_status & ~aer_regs->uncor_mask) {
-		if (aer_regs->uncor_status & PCI_ERR_ROOT_FATAL_RCV)
-			*severity = AER_FATAL;
-		else
-			*severity = AER_NONFATAL;
+	u32 uncor_status = aer_regs->uncor_status & ~aer_regs->uncor_mask;
+
+	if (uncor_status) {
+		*severity = (uncor_status & aer_regs->uncor_severity) ?
+			     AER_FATAL : AER_NONFATAL;
 		return true;
 	}
 
-- 
2.53.0