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virtio_pci: use shared interrupts for virtqueues

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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.

Additionally clean up the VQ allocation code to properly unwind on error
instead of having a single global cleanup label, which is error prone,
and in this case also leads to more code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Christoph Hellwig
2017-02-05 18:15:19 +01:00
committed by Michael S. Tsirkin
parent 5c34d002dc
commit 07ec51480b
2 changed files with 106 additions and 145 deletions
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16
drivers/virtio/virtio_pci_common.h
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@@ -66,16 +66,12 @@ 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;
/* Total Number of MSI-X vectors (including per-VQ ones). */
int msix_vectors;
/* Map of per-VQ MSI-X vectors, may be NULL */
unsigned *msix_vector_map;
@@ -89,14 +85,6 @@ 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)
{