Re: [dpdk-dev] [PATCH v2 09/10] igbuio: show irq mode in sysfs

[Stephen Hemminger <stephen@networkplumber.org>]

This is what I am testing, along with 10 other virtio patches.

Subject: virtio: check for using msix interrupt

Fix how the device driver detects MSI-X vs INTX mode.
Look in sysfs to find if MSI-X is enabled.

Suggested-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>


--- a/lib/librte_pmd_virtio/virtio_ethdev.c
+++ b/lib/librte_pmd_virtio/virtio_ethdev.c
@@ -709,6 +709,28 @@
 	return 0;
 }
 
+/*
+ * Detect if using INTX or MSI-X by looking for:
+ *  /sys/bus/pci/devices/<D:B:D.F>/msi_irqs/
+ * if directory exists, must be using msi-x
+ */
+static int
+has_msix(const struct rte_pci_addr *loc)
+{
+	DIR *d;
+	char dirname[PATH_MAX];
+
+	rte_snprintf(dirname, sizeof(dirname),
+		     SYSFS_PCI_DEVICES "/" PCI_PRI_FMT "/msi_irqs",
+		     loc->domain, loc->bus, loc->devid, loc->function);
+
+	d = opendir(dirname);
+	if (d)
+		closedir(d);
+
+	return (d != NULL);
+}
+
 static int get_uio_dev(struct rte_pci_addr *loc, char *buf, unsigned int buflen)
 {
 	unsigned int uio_num;
@@ -872,6 +894,8 @@
 		PMD_INIT_LOG(DEBUG,
 			     "PCI Port IO found start=0x%lx with size=0x%lx\n",
 			     start, size);
+
+		hw->use_msix = has_msix(&pci_dev->addr);
 	}
 #endif
 	hw->io_base = (uint32_t)(uintptr_t)pci_dev->mem_resource[0].addr;
--- a/lib/librte_pmd_virtio/virtio_pci.h
+++ b/lib/librte_pmd_virtio/virtio_pci.h
@@ -177,6 +177,7 @@
 	uint16_t    subsystem_device_id;
 	uint16_t    subsystem_vendor_id;
 	uint8_t     revision_id;
+	uint8_t	    use_msix;
 	uint8_t     mac_addr[ETHER_ADDR_LEN];
 	int         adapter_stopped;
 };
@@ -194,13 +195,11 @@
 	uint16_t   max_virtqueue_pairs;
 } __attribute__((packed));
 
-/* Value indicated in device config */
-#define VIRTIO_PCI_FLAG_MSIX  0x0020
 /*
  * The remaining space is defined by each driver as the per-driver
  * configuration space.
  */
-#define VIRTIO_PCI_CONFIG(hw) (((hw)->guest_features & VIRTIO_PCI_FLAG_MSIX) ? 24 : 20)
+#define VIRTIO_PCI_CONFIG(hw) (((hw)->use_msix) ? 24 : 20)
 
 /*
  * How many bits to shift physical queue address written to QUEUE_PFN.