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Date: Thu, 17 Nov 2016 11:43:17 +0100
From: Christoph Hellwig <hch@....de>
To: mst@...hat.com
Cc: axboe@...nel.dk, virtualization@...ts.linux-foundation.org,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 05/11] virtio_pci: use shared interrupts for virtqueues
This lets IRQ layer handle dispatching IRQs to separate handlers for the
case where we don't have per-VQ MSI-X vectors, and allows us to greatly
simplify the code based on the assumption that we always have interrupt
vector 0 (legacy INTx or config interrupt for MSI-X) available, and
any other interrupt is request/freed throught the VQ, even if the
actual interrupt line might be shared in some cases.
This allows removing a great deal of variables keeping track of the
interrupt state in struct virtio_pci_device, as we can now simply walk the
list of VQs and deal with per-VQ interrupt handlers there, and only treat
vector 0 special. As a little caveat this means we have to check if VQs
have been set up before calling vp_synchronize_vectors, as otherwise
the initial reset will trip over the uninitialized ->vqs array.
Signed-off-by: Christoph Hellwig <hch@....de>
---
drivers/virtio/virtio_pci_common.c | 95 ++++++++++++++------------------------
drivers/virtio/virtio_pci_common.h | 18 +-------
2 files changed, 36 insertions(+), 77 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 9a9826e..9e6c9d8 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -31,13 +31,18 @@ MODULE_PARM_DESC(force_legacy,
void vp_synchronize_vectors(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- int i;
+ struct virtqueue *vq, *n;
+
+ if (!vp_dev->vqs)
+ return;
- if (vp_dev->intx_enabled)
- synchronize_irq(vp_dev->pci_dev->irq);
+ list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
+ int vec = vp_dev->vqs[vq->index]->msix_vector;
+ if (vec != VIRTIO_MSI_NO_VECTOR)
+ synchronize_irq(pci_irq_vector(vp_dev->pci_dev, vec));
+ }
- for (i = 0; i < vp_dev->msix_vectors; ++i)
- synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
+ synchronize_irq(pci_irq_vector(vp_dev->pci_dev, 0));
}
/* the notify function used when creating a virt queue */
@@ -102,16 +107,14 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
return vp_vring_interrupt(irq, opaque);
}
-static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
- bool per_vq_vectors)
+static int vp_setup_msix_vectors(struct virtio_device *vdev, int nvectors)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
const char *name = dev_name(&vp_dev->vdev.dev);
- unsigned i, v;
+ unsigned i;
int err = -ENOMEM;
vp_dev->msix_vectors = nvectors;
-
vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
GFP_KERNEL);
if (!vp_dev->msix_names)
@@ -133,35 +136,20 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
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,
+ snprintf(vp_dev->msix_names[0], sizeof(*vp_dev->msix_names),
"%s-config", name);
- err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
- vp_config_changed, 0, vp_dev->msix_names[v],
+ err = request_irq(pci_irq_vector(vp_dev->pci_dev, 0),
+ vp_config_changed, 0, vp_dev->msix_names[0],
vp_dev);
if (err)
goto error;
- ++vp_dev->msix_used_vectors;
- v = vp_dev->config_vector(vp_dev, v);
/* Verify we had enough resources to assign the vector */
- if (v == VIRTIO_MSI_NO_VECTOR) {
+ if (vp_dev->config_vector(vp_dev, 0) == VIRTIO_MSI_NO_VECTOR) {
err = -EBUSY;
goto error;
}
- if (!per_vq_vectors) {
- /* 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(pci_irq_vector(vp_dev->pci_dev, v),
- vp_vring_interrupt, 0, vp_dev->msix_names[v],
- vp_dev);
- if (err)
- goto error;
- ++vp_dev->msix_used_vectors;
- }
return 0;
error:
return err;
@@ -224,24 +212,14 @@ void vp_del_vqs(struct virtio_device *vdev)
int i;
list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
- if (vp_dev->per_vq_vectors) {
- int v = vp_dev->vqs[vq->index]->msix_vector;
+ int vec = vp_dev->vqs[vq->index]->msix_vector;
- if (v != VIRTIO_MSI_NO_VECTOR)
- free_irq(pci_irq_vector(vp_dev->pci_dev, v),
- vq);
- }
+ if (vec != VIRTIO_MSI_NO_VECTOR)
+ free_irq(pci_irq_vector(vp_dev->pci_dev, vec), vq);
vp_del_vq(vq);
}
- vp_dev->per_vq_vectors = false;
-
- 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(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);
+ free_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_dev);
for (i = 0; i < vp_dev->msix_vectors; i++)
if (vp_dev->msix_affinity_masks[i])
@@ -256,7 +234,6 @@ void vp_del_vqs(struct virtio_device *vdev)
}
vp_dev->msix_vectors = 0;
- vp_dev->msix_used_vectors = 0;
kfree(vp_dev->msix_names);
vp_dev->msix_names = NULL;
kfree(vp_dev->msix_affinity_masks);
@@ -273,7 +250,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
u16 msix_vec;
- int i, err, nvectors, allocated_vectors;
+ int i, err, allocated_vectors, nvectors;
vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
if (!vp_dev->vqs)
@@ -290,46 +267,44 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
nvectors = 2;
}
- err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);
+ err = vp_setup_msix_vectors(vdev, nvectors);
if (err)
goto error_find;
- vp_dev->per_vq_vectors = per_vq_vectors;
- allocated_vectors = vp_dev->msix_used_vectors;
+ allocated_vectors = 1; /* vector 0 is the config interrupt */
for (i = 0; i < nvqs; ++i) {
if (!names[i]) {
vqs[i] = NULL;
continue;
}
- if (!callbacks[i])
- msix_vec = VIRTIO_MSI_NO_VECTOR;
- else if (vp_dev->per_vq_vectors)
- msix_vec = allocated_vectors++;
+ if (callbacks[i])
+ msix_vec = allocated_vectors;
else
- msix_vec = VP_MSIX_VQ_VECTOR;
+ msix_vec = VIRTIO_MSI_NO_VECTOR;
+
vqs[i] = vp_setup_vq(vdev, i, callbacks[i], names[i], msix_vec);
if (IS_ERR(vqs[i])) {
err = PTR_ERR(vqs[i]);
goto error_find;
}
- if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)
+ if (msix_vec == VIRTIO_MSI_NO_VECTOR)
continue;
- /* allocate per-vq irq if available and necessary */
snprintf(vp_dev->msix_names[msix_vec],
- sizeof *vp_dev->msix_names,
- "%s-%s",
+ sizeof(*vp_dev->msix_names), "%s-%s",
dev_name(&vp_dev->vdev.dev), names[i]);
err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
- vring_interrupt, 0,
- vp_dev->msix_names[msix_vec],
- vqs[i]);
+ vring_interrupt, IRQF_SHARED,
+ vp_dev->msix_names[msix_vec], vqs[i]);
if (err) {
vp_del_vq(vqs[i]);
goto error_find;
}
+
+ if (per_vq_vectors)
+ allocated_vectors++;
}
return 0;
@@ -354,8 +329,6 @@ static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs,
if (err)
goto out_del_vqs;
- vp_dev->intx_enabled = 1;
- vp_dev->per_vq_vectors = false;
for (i = 0; i < nvqs; ++i) {
if (!names[i]) {
vqs[i] = NULL;
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index b2f6662..93f3e4f 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -84,18 +84,12 @@ struct virtio_pci_device {
/* MSI-X support */
int msix_enabled;
- int intx_enabled;
cpumask_var_t *msix_affinity_masks;
/* 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, excluding per-vq vectors if any */
- unsigned msix_used_vectors;
-
- /* Whether we have vector per vq */
- bool per_vq_vectors;
+ /* Total Number of MSI-X vectors (including per-VQ ones). */
+ int msix_vectors;
struct virtqueue *(*setup_vq)(struct virtio_pci_device *vp_dev,
struct virtio_pci_vq_info *info,
@@ -108,14 +102,6 @@ struct virtio_pci_device {
u16 (*config_vector)(struct virtio_pci_device *vp_dev, u16 vector);
};
-/* 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,
-};
-
/* Convert a generic virtio device to our structure */
static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
{
--
2.1.4
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