queue-5.10/scsi-lpfc-properly-set-wc-for-dpp-mapping.patch

From f814461c7e3165a3b460d748ee184bc7f0eccafe Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 12 Feb 2026 11:23:27 -0800
Subject: scsi: lpfc: Properly set WC for DPP mapping

From: Mathias Krause <minipli@grsecurity.net>

[ Upstream commit bffda93a51b40afd67c11bf558dc5aae83ca0943 ]

Using set_memory_wc() to enable write-combining for the DPP portion of
the MMIO mapping is wrong as set_memory_*() is meant to operate on RAM
only, not MMIO mappings. In fact, as used currently triggers a BUG_ON()
with enabled CONFIG_DEBUG_VIRTUAL.

Simply map the DPP region separately and in addition to the already
existing mappings, avoiding any possible negative side effects for
these.

Fixes: 1351e69fc6db ("scsi: lpfc: Add push-to-adapter support to sli4")
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Reviewed-by: Mathias Krause <minipli@grsecurity.net>
Link: https://patch.msgid.link/20260212192327.141104-1-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/lpfc/lpfc_init.c |  2 ++
 drivers/scsi/lpfc/lpfc_sli.c  | 36 +++++++++++++++++++++++++++++------
 drivers/scsi/lpfc/lpfc_sli4.h |  3 +++
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 5f2009327a593..0f144fbf2a6cb 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -10558,6 +10558,8 @@ lpfc_sli4_pci_mem_unset(struct lpfc_hba *phba)
 		iounmap(phba->sli4_hba.conf_regs_memmap_p);
 		if (phba->sli4_hba.dpp_regs_memmap_p)
 			iounmap(phba->sli4_hba.dpp_regs_memmap_p);
+		if (phba->sli4_hba.dpp_regs_memmap_wc_p)
+			iounmap(phba->sli4_hba.dpp_regs_memmap_wc_p);
 		break;
 	case LPFC_SLI_INTF_IF_TYPE_1:
 	default:
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 49931577da38b..0b3242b058b99 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -14966,6 +14966,32 @@ lpfc_dual_chute_pci_bar_map(struct lpfc_hba *phba, uint16_t pci_barset)
 	return NULL;
 }
 
+static __maybe_unused void __iomem *
+lpfc_dpp_wc_map(struct lpfc_hba *phba, uint8_t dpp_barset)
+{
+
+	/* DPP region is supposed to cover 64-bit BAR2 */
+	if (dpp_barset != WQ_PCI_BAR_4_AND_5) {
+		lpfc_log_msg(phba, KERN_WARNING, LOG_INIT,
+			     "3273 dpp_barset x%x != WQ_PCI_BAR_4_AND_5\n",
+			     dpp_barset);
+		return NULL;
+	}
+
+	if (!phba->sli4_hba.dpp_regs_memmap_wc_p) {
+		void __iomem *dpp_map;
+
+		dpp_map = ioremap_wc(phba->pci_bar2_map,
+				     pci_resource_len(phba->pcidev,
+						      PCI_64BIT_BAR4));
+
+		if (dpp_map)
+			phba->sli4_hba.dpp_regs_memmap_wc_p = dpp_map;
+	}
+
+	return phba->sli4_hba.dpp_regs_memmap_wc_p;
+}
+
 /**
  * lpfc_modify_hba_eq_delay - Modify Delay Multiplier on EQs
  * @phba: HBA structure that EQs are on.
@@ -15876,9 +15902,6 @@ lpfc_wq_create(struct lpfc_hba *phba, struct lpfc_queue *wq,
 	uint8_t dpp_barset;
 	uint32_t dpp_offset;
 	uint8_t wq_create_version;
-#ifdef CONFIG_X86
-	unsigned long pg_addr;
-#endif
 
 	/* sanity check on queue memory */
 	if (!wq || !cq)
@@ -16070,14 +16093,15 @@ lpfc_wq_create(struct lpfc_hba *phba, struct lpfc_queue *wq,
 
 #ifdef CONFIG_X86
 			/* Enable combined writes for DPP aperture */
-			pg_addr = (unsigned long)(wq->dpp_regaddr) & PAGE_MASK;
-			rc = set_memory_wc(pg_addr, 1);
-			if (rc) {
+			bar_memmap_p = lpfc_dpp_wc_map(phba, dpp_barset);
+			if (!bar_memmap_p) {
 				lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
 					"3272 Cannot setup Combined "
 					"Write on WQ[%d] - disable DPP\n",
 					wq->queue_id);
 				phba->cfg_enable_dpp = 0;
+			} else {
+				wq->dpp_regaddr = bar_memmap_p + dpp_offset;
 			}
 #else
 			phba->cfg_enable_dpp = 0;
diff --git a/drivers/scsi/lpfc/lpfc_sli4.h b/drivers/scsi/lpfc/lpfc_sli4.h
index 100cb1a94811b..80c168b2a2ddd 100644
--- a/drivers/scsi/lpfc/lpfc_sli4.h
+++ b/drivers/scsi/lpfc/lpfc_sli4.h
@@ -772,6 +772,9 @@ struct lpfc_sli4_hba {
 	void __iomem *dpp_regs_memmap_p;  /* Kernel memory mapped address for
 					   * dpp registers
 					   */
+	void __iomem *dpp_regs_memmap_wc_p;/* Kernel memory mapped address for
+					    * dpp registers with write combining
+					    */
 	union {
 		struct {
 			/* IF Type 0, BAR 0 PCI cfg space reg mem map */
-- 
2.51.0