[ipxe-devel] [PATCH v3 4/4] [virtio] Add virtio-net 1.0 support

[Michael S. Tsirkin]

On Tue, Apr 05, 2016 at 05:38:24PM +0200, Ladi Prosek wrote:
> +	/* Enable the PCI device only if we need to */
> +	if ( ( virtnet->vdev.common.flags & VIRTIO_PCI_REGION_TYPE_MASK ) !=
> +		VIRTIO_PCI_REGION_PCI_CONFIG ||
> +	     ( virtnet->vdev.isr.flags & VIRTIO_PCI_REGION_TYPE_MASK ) !=
> +		VIRTIO_PCI_REGION_PCI_CONFIG ||
> +	     ( device && ( virtnet->vdev.device.flags & VIRTIO_PCI_REGION_TYPE_MASK ) !=
> +		VIRTIO_PCI_REGION_PCI_CONFIG ) ) {
> +		/* At least one BAR has been mapped */
> +		adjust_pci_device ( pci );
> +		virtnet->vdev.pci_device_initialized = 1;
> +	}


This is slightly wrong for two reasons:
	- it does not enable bus mastering
	- unused BAR types are also enabled.

How about using the following to enable exactly what's
needed:

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>

diff --git a/src/include/ipxe/pci.h b/src/include/ipxe/pci.h
index 89d9d80..e22ff54 100644
--- a/src/include/ipxe/pci.h
+++ b/src/include/ipxe/pci.h
@@ -278,6 +278,8 @@ struct pci_driver {
 	PCI_FUNC ( (pci)->busdevfn )
 
 extern void adjust_pci_device ( struct pci_device *pci );
+extern unsigned enable_pci_device ( struct pci_device *pci, unsigned flags );
+extern void disable_pci_device ( struct pci_device *pci, unsigned flags );
 extern unsigned long pci_bar_start ( struct pci_device *pci,
 				     unsigned int reg );
 extern int pci_read_config ( struct pci_device *pci );
diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c
index 6fbedd9..6befb67 100644
--- a/src/drivers/bus/pci.c
+++ b/src/drivers/bus/pci.c
@@ -169,6 +169,49 @@ void adjust_pci_device ( struct pci_device *pci ) {
 }
 
 /**
+ * Enable PCI device
+ *
+ * @v pci		PCI device
+ * @v flags		Flags to enable
+ * @ret rc		Original flags
+ *
+ * Enable device in case BIOS neglected to do so.  Also
+ * adjust PCI latency timer to a reasonable value, 32.
+ */
+unsigned enable_pci_device ( struct pci_device *pci, unsigned flags ) {
+	unsigned short new_command, pci_command;
+	unsigned char pci_latency;
+
+	pci_read_config_word ( pci, PCI_COMMAND, &pci_command );
+	new_command = ( pci_command | flags );
+	if ( pci_command != new_command ) {
+		DBGC ( pci, PCI_FMT " device not enabled by BIOS! Updating "
+		       "PCI command %04x->%04x\n",
+		       PCI_ARGS ( pci ), pci_command, new_command );
+		pci_write_config_word ( pci, PCI_COMMAND, new_command );
+	}
+
+	pci_read_config_byte ( pci, PCI_LATENCY_TIMER, &pci_latency);
+	if ( pci_latency < 32 ) {
+		DBGC ( pci, PCI_FMT " latency timer is unreasonably low at "
+		       "%d. Setting to 32.\n", PCI_ARGS ( pci ), pci_latency );
+		pci_write_config_byte ( pci, PCI_LATENCY_TIMER, 32);
+	}
+}
+
+/**
+ * Disable PCI device
+ *
+ * @v pci		PCI device
+ * @v flags		Flags to restore
+ *
+ * Restore device to state it had before we enabled it.
+ */
+void disable_pci_device ( struct pci_device *pci, unsigned flags ) {
+	pci_write_config_word ( pci, PCI_COMMAND, flags );
+}
+
+/**
  * Read PCI device configuration
  *
  * @v pci		PCI device