scsi: lpfc: Properly set WC for DPP mapping

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>

3 files changed, 35 insertions, 6 deletions

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index a116a16c4a6f..b5e53c7d33e7 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -12039,6 +12039,8 @@ 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:
 		break;
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 734af3d039f8..690763e0aa55 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -15981,6 +15981,32 @@ 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.
@@ -16944,9 +16970,6 @@ 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)
@@ -17132,14 +17155,15 @@ 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 ee58383492b2..b6d90604bb61 100644
--- a/drivers/scsi/lpfc/lpfc_sli4.h
+++ b/drivers/scsi/lpfc/lpfc_sli4.h
@@ -785,6 +785,9 @@ 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 */