[PATCH 3/3] virtio_pci: optional MSI-X support
This implements optional MSI-X support in virtio_pci.
MSI-X is used whenever the host supports at least 2 MSI-X
vectors: 1 for configuration changes and 1 for virtqueues.
Per-virtqueue vectors are allocated if enough vectors
available.
Signed-off-by: Michael S. Tsirkin m...@redhat.com
---
drivers/virtio/virtio_pci.c | 211 +++
include/linux/virtio_pci.h |8 ++-
2 files changed, 199 insertions(+), 20 deletions(-)
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index a6bebe2..d21e2e6 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,6 +42,29 @@ struct virtio_pci_device
/* a list of queues so we can dispatch IRQs */
spinlock_t lock;
struct list_head virtqueues;
+
+ /* MSI-X support */
+ int msix_enabled;
+ int intx_enabled;
+ struct msix_entry *msix_entries;
+ /* Name strings for interrupts. This size should be enough,
+* and I'm too lazy to allocate each name separately. */
+ char (*msix_names)[256];
+ /* Number of vectors configured at startup (excludes per-virtqueue
+* vectors if any) */
+ unsigned msix_preset_vectors;
+ /* Number of per-virtqueue vectors if any. */
+ unsigned msix_per_vq_vectors;
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+ VP_MSIX_CONFIG_VECTOR = 0,
+ VP_MSIX_VQ_VECTOR = 1,
+ VP_MSIX_MIN_VECTORS = 2,
+ VP_MSIX_NO_VECTOR = 0x,
};
struct virtio_pci_vq_info
@@ -60,6 +83,9 @@ struct virtio_pci_vq_info
/* the list node for the virtqueues list */
struct list_head node;
+
+ /* MSI-X vector (or none) */
+ unsigned vector;
};
/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
@@ -109,7 +135,8 @@ static void vp_get(struct virtio_device *vdev, unsigned
offset,
void *buf, unsigned len)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- void __iomem *ioaddr = vp_dev-ioaddr + VIRTIO_PCI_CONFIG + offset;
+ void __iomem *ioaddr = vp_dev-ioaddr +
+ VIRTIO_PCI_CONFIG(vp_dev) + offset;
u8 *ptr = buf;
int i;
@@ -123,7 +150,8 @@ static void vp_set(struct virtio_device *vdev, unsigned
offset,
const void *buf, unsigned len)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- void __iomem *ioaddr = vp_dev-ioaddr + VIRTIO_PCI_CONFIG + offset;
+ void __iomem *ioaddr = vp_dev-ioaddr +
+ VIRTIO_PCI_CONFIG(vp_dev) + offset;
const u8 *ptr = buf;
int i;
@@ -221,7 +249,116 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
return vp_vring_interrupt(irq, opaque);
}
-/* the config-find_vq() implementation */
+static void vp_free_vectors(struct virtio_device *vdev) {
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ int i;
+
+ if (vp_dev-intx_enabled) {
+ free_irq(vp_dev-pci_dev-irq, vp_dev);
+ vp_dev-intx_enabled = 0;
+ }
+
+ for (i = 0; i vp_dev-msix_preset_vectors; ++i)
+ free_irq(vp_dev-msix_entries[i].vector, vp_dev);
+ vp_dev-msix_preset_vectors = 0;
+
+ if (vp_dev-msix_enabled) {
+ /* Disable the vector used for configuration */
+ iowrite16(VP_MSIX_NO_VECTOR,
+ vp_dev-ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+
+ vp_dev-msix_enabled = 0;
+ pci_disable_msix(vp_dev-pci_dev);
+ }
+}
+
+static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
+{
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ const char *name = dev_name(vp_dev-vdev.dev);
+ unsigned i, vectors;
+ int err = -ENOMEM;
+
+ /* We need at most one vector per queue and one for config changes */
+ vectors = VP_MSIX_VQ_VECTOR + max_vqs;
+ vp_dev-msix_entries = kmalloc(vectors * sizeof *vp_dev-msix_entries,
+ GFP_KERNEL);
+ if (!vp_dev-msix_entries)
+ goto error_entries;
+ vp_dev-msix_names = kmalloc(vectors * sizeof *vp_dev-msix_names,
+GFP_KERNEL);
+ if (!vp_dev-msix_names)
+ goto error_names;
+
+ snprintf(vp_dev-msix_names[VP_MSIX_CONFIG_VECTOR],
+sizeof *vp_dev-msix_names, %s-config, name);
+ for (i = 0; i max_vqs; ++i)
+ snprintf(vp_dev-msix_names[i + VP_MSIX_VQ_VECTOR],
+sizeof *vp_dev-msix_names, %s-vq-%d, name, i);
+ for (i = 0; i vectors; ++i)
+ vp_dev-msix_entries[i].entry = i;
+
+ vp_dev-msix_preset_vectors = 1;
+ vp_dev-msix_per_vq_vectors = max_vqs;
+ for (;;) {
+
[PATCH 3/3] virtio_pci: optional MSI-X support
This implements optional MSI-X support in virtio_pci.
MSI-X is used whenever the host supports at least 2 MSI-X
vectors: 1 for configuration changes and 1 for virtqueues.
Per-virtqueue vectors are allocated if enough vectors
available.
Signed-off-by: Michael S. Tsirkin m...@redhat.com
---
drivers/virtio/virtio_pci.c | 209 +--
include/linux/virtio_pci.h |8 ++-
2 files changed, 190 insertions(+), 27 deletions(-)
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
index cd0fd5d..4a0275b 100644
--- a/include/linux/virtio_pci.h
+++ b/include/linux/virtio_pci.h
@@ -47,9 +47,15 @@
/* The bit of the ISR which indicates a device configuration change. */
#define VIRTIO_PCI_ISR_CONFIG 0x2
+/* MSI-X registers: only enabled if MSI-X is enabled. */
+/* A 16-bit vector for configuration changes. */
+#define VIRTIO_MSI_CONFIG_VECTOR20
+/* A 16-bit vector for selected queue notifications. */
+#define VIRTIO_MSI_QUEUE_VECTOR 22
+
/* The remaining space is defined by each driver as the per-driver
* configuration space */
-#define VIRTIO_PCI_CONFIG 20
+#define VIRTIO_PCI_CONFIG(dev) ((dev)-msix_enabled ? 24 : 20)
/* Virtio ABI version, this must match exactly */
#define VIRTIO_PCI_ABI_VERSION 0
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index f7b79a2..2b6333c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,6 +42,28 @@ struct virtio_pci_device
/* a list of queues so we can dispatch IRQs */
spinlock_t lock;
struct list_head virtqueues;
+
+ /* MSI-X support */
+ int msix_enabled;
+ struct msix_entry *msix_entries;
+ /* Name strings for interrupts. This size should be enough,
+* and I'm too lazy to allocate each name separately. */
+ char (*msix_names)[256];
+ /* Number of vectors configured at startup (excludes per-virtqueue
+* vectors if any) */
+ unsigned msix_preset_vectors;
+ /* Number of per-virtqueue vectors if any. */
+ unsigned msix_per_vq_vectors;
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+ VP_MSIX_CONFIG_VECTOR = 0,
+ VP_MSIX_VQ_VECTOR = 1,
+ VP_MSIX_MIN_VECTORS = 2,
+ VP_MSIX_NO_VECTOR = 0x,
};
struct virtio_pci_vq_info
@@ -60,6 +82,9 @@ struct virtio_pci_vq_info
/* the list node for the virtqueues list */
struct list_head node;
+
+ /* MSI-X vector (or none) */
+ unsigned vector;
};
/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
@@ -109,7 +134,8 @@ static void vp_get(struct virtio_device *vdev, unsigned
offset,
void *buf, unsigned len)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- void __iomem *ioaddr = vp_dev-ioaddr + VIRTIO_PCI_CONFIG + offset;
+ void __iomem *ioaddr = vp_dev-ioaddr +
+ VIRTIO_PCI_CONFIG(vp_dev) + offset;
u8 *ptr = buf;
int i;
@@ -123,7 +149,8 @@ static void vp_set(struct virtio_device *vdev, unsigned
offset,
const void *buf, unsigned len)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- void __iomem *ioaddr = vp_dev-ioaddr + VIRTIO_PCI_CONFIG + offset;
+ void __iomem *ioaddr = vp_dev-ioaddr +
+ VIRTIO_PCI_CONFIG(vp_dev) + offset;
const u8 *ptr = buf;
int i;
@@ -221,17 +248,110 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
return vp_vring_interrupt(irq, opaque);
}
- spin_lock_irqsave(vp_dev-lock, flags);
- list_for_each_entry(info, vp_dev-virtqueues, node) {
- if (vring_interrupt(irq, info-vq) == IRQ_HANDLED)
- ret = IRQ_HANDLED;
+/* the config-free_vqs() implementation */
+static void vp_free_vectors(struct virtio_device *vdev) {
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ int i;
+
+ /* Disable the vector used for configuration */
+ iowrite16(VP_MSIX_NO_VECTOR,
+ vp_dev-ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+
+ for (i = 0; i vp_dev-msix_preset_vectors; ++i)
+ free_irq(vp_dev-msix_entries[i].vector, vp_dev);
+
+ if (!vp_dev-msix_preset_vectors)
+ free_irq(vp_dev-pci_dev-irq, vp_dev);
+
+ if (vp_dev-msix_enabled) {
+ vp_dev-msix_enabled = 0;
+ pci_disable_msix(vp_dev-pci_dev);
}
- spin_unlock_irqrestore(vp_dev-lock, flags);
+}
- return ret;
+static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
+{
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ const char *name = dev_name(vp_dev-vdev.dev);
+ unsigned i, vectors;
+ int err =
