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 <mst at redhat.com>
---
drivers/virtio/virtio_pci.c | 227 +++++++++++++++++++++++++++++++++++++++----
include/linux/virtio_pci.h | 10 ++-
2 files changed, 217 insertions(+), 20 deletions(-)
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 951e673..65627a4 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,6 +42,26 @@ 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 available vectors */
+ unsigned msix_vectors;
+ /* Vectors allocated */
+ unsigned msix_used_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,
};
struct virtio_pci_vq_info
@@ -60,6 +80,9 @@ 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 +132,8 @@ 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 +147,8 @@ 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 +246,121 @@ 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_used_vectors; ++i)
+ free_irq(vp_dev->msix_entries[i].vector, vp_dev);
+ vp_dev->msix_used_vectors = 0;
+
+ if (vp_dev->msix_enabled) {
+ /* Disable the vector used for configuration */
+ iowrite16(VIRTIO_MSI_NO_VECTOR,
+ vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+ /* Flush the write out to device */
+ ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+
+ vp_dev->msix_enabled = 0;
+ pci_disable_msix(vp_dev->pci_dev);
+ }
+}
+
+static int vp_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
+ int *options, int noptions)
+{
+ int i;
+ for (i = 0; i < noptions; ++i)
+ if (!pci_enable_msix(dev, entries, options[i]))
+ return options[i];
+ return -EBUSY;
+}
+
+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, v;
+ int err = -ENOMEM;
+ /* We want at most one vector per queue and one for config changes.
+ * Fallback to separate vectors for config and a shared for queues.
+ * Finally fall back to regular interrupts. */
+ int options[] = { max_vqs + 1, 2 };
+ int nvectors = max(options[0], options[1]);
+
+ vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
+ GFP_KERNEL);
+ if (!vp_dev->msix_entries)
+ goto error_entries;
+ vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
+ GFP_KERNEL);
+ if (!vp_dev->msix_names)
+ goto error_names;
+
+ for (i = 0; i < nvectors; ++i)
+ vp_dev->msix_entries[i].entry = i;
+
+ err = vp_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries,
+ options, ARRAY_SIZE(options));
+ if (err < 0) {
+ /* Can't allocate enough MSI-X vectors, use regular interrupt */
+ vp_dev->msix_vectors = 0;
+ err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
+ IRQF_SHARED, name, vp_dev);
+ if (err)
+ goto error_irq;
+ vp_dev->intx_enabled = 1;
+ } else {
+ vp_dev->msix_vectors = err;
+ vp_dev->msix_enabled = 1;
+
+ /* Set the vector used for configuration */
+ v = vp_dev->msix_used_vectors;
+ snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+ "%s-config", name);
+ err = request_irq(vp_dev->msix_entries[v].vector,
+ vp_config_changed, 0, vp_dev->msix_names[v],
+ vp_dev);
+ if (err)
+ goto error_irq;
+ ++vp_dev->msix_used_vectors;
+
+ iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+ /* Verify we had enough resources to assign the vector */
+ v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+ if (v == VIRTIO_MSI_NO_VECTOR) {
+ err = -EBUSY;
+ goto error_irq;
+ }
+ }
+
+ if (vp_dev->msix_vectors && vp_dev->msix_vectors != max_vqs + 1)
{
+ /* Shared vector for all VQs */
+ v = vp_dev->msix_used_vectors;
+ snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+ "%s-virtqueues", name);
+ err = request_irq(vp_dev->msix_entries[v].vector,
+ vp_vring_interrupt, 0, vp_dev->msix_names[v],
+ vp_dev);
+ if (err)
+ goto error_irq;
+ ++vp_dev->msix_used_vectors;
+ }
+ return 0;
+error_irq:
+ vp_free_vectors(vdev);
+ kfree(vp_dev->msix_names);
+error_names:
+ kfree(vp_dev->msix_entries);
+error_entries:
+ return err;
+}
+
static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
void (*callback)(struct virtqueue *vq),
const char *name)
@@ -230,7 +369,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device
*vdev, unsigned index,
struct virtio_pci_vq_info *info;
struct virtqueue *vq;
unsigned long flags, size;
- u16 num;
+ u16 num, vector;
int err;
/* Select the queue we're interested in */
@@ -249,6 +388,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device
*vdev, unsigned index,
info->queue_index = index;
info->num = num;
+ info->vector = VIRTIO_MSI_NO_VECTOR;
size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
@@ -272,12 +412,43 @@ static struct virtqueue *vp_find_vq(struct virtio_device
*vdev, unsigned index,
vq->priv = info;
info->vq = vq;
+ /* allocate per-vq vector if available and necessary */
+ if (callback && vp_dev->msix_used_vectors <
vp_dev->msix_vectors) {
+ vector = vp_dev->msix_used_vectors;
+ snprintf(vp_dev->msix_names[vector], sizeof *vp_dev->msix_names,
+ "%s-%s", dev_name(&vp_dev->vdev.dev), name);
+ err = request_irq(vp_dev->msix_entries[vector].vector,
+ vring_interrupt, 0,
+ vp_dev->msix_names[vector], vq);
+ if (err)
+ goto out_request_irq;
+ info->vector = vector;
+ ++vp_dev->msix_used_vectors;
+ } else
+ vector = VP_MSIX_VQ_VECTOR;
+
+ if (callback && vp_dev->msix_enabled) {
+ iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+ vector = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+ if (vector == VIRTIO_MSI_NO_VECTOR) {
+ err = -EBUSY;
+ goto out_assign;
+ }
+ }
+
spin_lock_irqsave(&vp_dev->lock, flags);
list_add(&info->node, &vp_dev->virtqueues);
spin_unlock_irqrestore(&vp_dev->lock, flags);
return vq;
+out_assign:
+ if (info->vector != VIRTIO_MSI_NO_VECTOR) {
+ free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+ --vp_dev->msix_used_vectors;
+ }
+out_request_irq:
+ vring_del_virtqueue(vq);
out_activate_queue:
iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
free_pages_exact(info->queue, size);
@@ -286,17 +457,27 @@ out_info:
return ERR_PTR(err);
}
-/* the config->del_vq() implementation */
static void vp_del_vq(struct virtqueue *vq)
{
struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
struct virtio_pci_vq_info *info = vq->priv;
unsigned long size;
+ iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+
+ if (info->vector != VIRTIO_MSI_NO_VECTOR)
+ free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+
+ if (vp_dev->msix_enabled) {
+ iowrite16(VIRTIO_MSI_NO_VECTOR,
+ vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+ /* Flush the write out to device */
+ ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
+ }
+
vring_del_virtqueue(vq);
/* Select and deactivate the queue */
- iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
size = PAGE_ALIGN(vring_size(info->num, VIRTIO_PCI_VRING_ALIGN));
@@ -304,30 +485,46 @@ static void vp_del_vq(struct virtqueue *vq)
kfree(info);
}
+/* the config->del_vqs() implementation */
static void vp_del_vqs(struct virtio_device *vdev)
{
struct virtqueue *vq, *n;
list_for_each_entry_safe(vq, n, &vdev->vqs, list)
vp_del_vq(vq);
+
+ vp_free_vectors(vdev);
}
+/* the config->find_vqs() implementation */
static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
const char *names[])
{
- int i;
+ int vectors = 0;
+ int i, err;
+
+ /* How many vectors would we like? */
+ for (i = 0; i < nvqs; ++i)
+ if (callbacks[i])
+ ++vectors;
+
+ err = vp_request_vectors(vdev, vectors);
+ if (err)
+ goto error_request;
for (i = 0; i < nvqs; ++i) {
vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i]);
if (IS_ERR(vqs[i]))
- goto error;
+ goto error_find;
}
return 0;
-error:
+error_find:
vp_del_vqs(vdev);
+
+error_request:
return PTR_ERR(vqs[i]);
}
@@ -349,7 +546,7 @@ static void virtio_pci_release_dev(struct device *_d)
struct virtio_pci_device *vp_dev = to_vp_device(dev);
struct pci_dev *pci_dev = vp_dev->pci_dev;
- free_irq(pci_dev->irq, vp_dev);
+ vp_del_vqs(dev);
pci_set_drvdata(pci_dev, NULL);
pci_iounmap(pci_dev, vp_dev->ioaddr);
pci_release_regions(pci_dev);
@@ -408,21 +605,13 @@ static int __devinit virtio_pci_probe(struct pci_dev
*pci_dev,
vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
vp_dev->vdev.id.device = pci_dev->subsystem_device;
- /* register a handler for the queue with the PCI device's interrupt */
- err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
- dev_name(&vp_dev->vdev.dev), vp_dev);
- if (err)
- goto out_set_drvdata;
-
/* finally register the virtio device */
err = register_virtio_device(&vp_dev->vdev);
if (err)
- goto out_req_irq;
+ goto out_set_drvdata;
return 0;
-out_req_irq:
- free_irq(pci_dev->irq, vp_dev);
out_set_drvdata:
pci_set_drvdata(pci_dev, NULL);
pci_iounmap(pci_dev, vp_dev->ioaddr);
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
index cd0fd5d..9a3d7c4 100644
--- a/include/linux/virtio_pci.h
+++ b/include/linux/virtio_pci.h
@@ -47,9 +47,17 @@
/* 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_VECTOR 20
+/* A 16-bit vector for selected queue notifications. */
+#define VIRTIO_MSI_QUEUE_VECTOR 22
+/* Vector value used to disable MSI for queue */
+#define VIRTIO_MSI_NO_VECTOR 0xffff
+
/* 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
--
1.6.3.rc3.1.g830204