event/dlb2: add support for disabling PASID

vfio-pci driver in Linux kernel 6.2 enables PASID by default.
In DLB hardware, enabling PASID puts DLB in SIOV mode. This
breaks DLB PF-PMD mode. For DLB PF-PMD mode to function properly
PASID needs to be disabled for kernel 6.2.

In this commit this issue is addressed and PASID is disabled
by writing a zero to PASID control register.

Signed-off-by: Abdullah Sevincer <abdullah.sevincer@intel.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

drivers/event/dlb2/pf/dlb2_main.c

@@ -46,6 +46,7 @@
 #define DLB2_PCI_CAP_ID_MSIX      0x11
 #define DLB2_PCI_EXT_CAP_ID_PRI   0x13
 #define DLB2_PCI_EXT_CAP_ID_ACS   0xD
+#define DLB2_PCI_EXT_CAP_ID_PASID 0x1B	/* Process Address Space ID */
 
 #define DLB2_PCI_PRI_CTRL_ENABLE         0x1
 #define DLB2_PCI_PRI_ALLOC_REQ           0xC
@@ -64,6 +65,8 @@
 #define DLB2_PCI_ACS_CR                  0x8
 #define DLB2_PCI_ACS_UF                  0x10
 #define DLB2_PCI_ACS_EC                  0x20
+#define DLB2_PCI_PASID_CTRL              0x06    /* PASID control register */
+#define DLB2_PCI_PASID_CAP_OFFSET        0x148   /* PASID capability offset */
 
 static int dlb2_pci_find_capability(struct rte_pci_device *pdev, uint32_t id)
 {
@@ -257,12 +260,14 @@ dlb2_pf_reset(struct dlb2_dev *dlb2_dev)
 	uint16_t rt_ctl_word;
 	uint32_t pri_reqs_dword;
 	uint16_t pri_ctrl_word;
+	uint16_t pasid_ctrl;
 
 	int pcie_cap_offset;
 	int pri_cap_offset;
 	int msix_cap_offset;
 	int err_cap_offset;
 	int acs_cap_offset;
+	int pasid_cap_offset;
 	int wait_count;
 
 	uint16_t devsta_busy_word;
@@ -582,6 +587,28 @@ dlb2_pf_reset(struct dlb2_dev *dlb2_dev)
 		}
 	}
 
+	/* The current Linux kernel vfio driver does not expose PASID capability to
+	 * users. It also enables PASID by default, which breaks DLB PF PMD. We have
+	 * to use the hardcoded offset for now to disable PASID.
+	 */
+	pasid_cap_offset = DLB2_PCI_PASID_CAP_OFFSET;
+
+	off = pasid_cap_offset + DLB2_PCI_PASID_CTRL;
+	if (rte_pci_read_config(pdev, &pasid_ctrl, 2, off) != 2)
+		pasid_ctrl = 0;
+
+	if (pasid_ctrl) {
+		DLB2_INFO(dlb2_dev, "DLB2 disabling pasid...\n");
+
+		pasid_ctrl = 0;
+		ret = rte_pci_write_config(pdev, &pasid_ctrl, 2, off);
+		if (ret != 2) {
+			DLB2_LOG_ERR("[%s()] failed to write the pcie config space at offset %d\n",
+				__func__, (int)off);
+			return ret;
+		}
+	}
+
 	return 0;
 }