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virtio/vhost: Add support for KVM in-kernel MSI injection

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Make use of the new vector notifier to track changes of the MSI-X
configuration of virtio PCI devices. On enabling events, we establish
the required virtual IRQ to MSI-X message route and link the signaling
eventfd file descriptor to this vIRQ line. That way, vhost-generated
interrupts can be directly delivered to an in-kernel MSI-X consumer like
the x86 APIC.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Jan Kiszka 2012-05-17 10:32:39 -03:00 committed by Avi Kivity
parent cb697aaab9
commit 7d37d351df
2 changed files with 132 additions and 0 deletions
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126
hw/virtio-pci.c
View File

@ -24,6 +24,7 @@
#include "virtio-scsi.h"
#include "pci.h"
#include "qemu-error.h"
#include "msi.h"
#include "msix.h"
#include "net.h"
#include "loader.h"
@ -539,6 +540,107 @@ static void virtio_pci_guest_notifier_read(void *opaque)
}
}
static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
unsigned int queue_no,
unsigned int vector,
MSIMessage msg)
{
VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no);
VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
int fd, ret;
fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vq));
if (irqfd->users == 0) {
ret = kvm_irqchip_add_msi_route(kvm_state, msg);
if (ret < 0) {
return ret;
}
irqfd->virq = ret;
}
irqfd->users++;
ret = kvm_irqchip_add_irqfd(kvm_state, fd, irqfd->virq);
if (ret < 0) {
if (--irqfd->users == 0) {
kvm_irqchip_release_virq(kvm_state, irqfd->virq);
}
return ret;
}
qemu_set_fd_handler(fd, NULL, NULL, NULL);
return 0;
}
static void kvm_virtio_pci_vq_vector_release(VirtIOPCIProxy *proxy,
unsigned int queue_no,
unsigned int vector)
{
VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no);
VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
int fd, ret;
fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vq));
ret = kvm_irqchip_remove_irqfd(kvm_state, fd, irqfd->virq);
assert(ret == 0);
if (--irqfd->users == 0) {
kvm_irqchip_release_virq(kvm_state, irqfd->virq);
}
qemu_set_fd_handler(fd, virtio_pci_guest_notifier_read, NULL, vq);
}
static int kvm_virtio_pci_vector_use(PCIDevice *dev, unsigned vector,
MSIMessage msg)
{
VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev);
VirtIODevice *vdev = proxy->vdev;
int ret, queue_no;
for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
if (!virtio_queue_get_num(vdev, queue_no)) {
break;
}
if (virtio_queue_vector(vdev, queue_no) != vector) {
continue;
}
ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector, msg);
if (ret < 0) {
goto undo;
}
}
return 0;
undo:
while (--queue_no >= 0) {
if (virtio_queue_vector(vdev, queue_no) != vector) {
continue;
}
kvm_virtio_pci_vq_vector_release(proxy, queue_no, vector);
}
return ret;
}
static void kvm_virtio_pci_vector_release(PCIDevice *dev, unsigned vector)
{
VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev);
VirtIODevice *vdev = proxy->vdev;
int queue_no;
for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
if (!virtio_queue_get_num(vdev, queue_no)) {
break;
}
if (virtio_queue_vector(vdev, queue_no) != vector) {
continue;
}
kvm_virtio_pci_vq_vector_release(proxy, queue_no, vector);
}
}
static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign)
{
VirtIOPCIProxy *proxy = opaque;
@ -555,6 +657,9 @@ static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign)
} else {
qemu_set_fd_handler(event_notifier_get_fd(notifier),
NULL, NULL, NULL);
/* Test and clear notifier before closing it,
* in case poll callback didn't have time to run. */
virtio_pci_guest_notifier_read(vq);
event_notifier_cleanup(notifier);
}
@ -573,6 +678,13 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign)
VirtIODevice *vdev = proxy->vdev;
int r, n;
/* Must unset vector notifier while guest notifier is still assigned */
if (kvm_irqchip_in_kernel() && !assign) {
msix_unset_vector_notifiers(&proxy->pci_dev);
g_free(proxy->vector_irqfd);
proxy->vector_irqfd = NULL;
}
for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
if (!virtio_queue_get_num(vdev, n)) {
break;
@ -584,10 +696,24 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign)
}
}
/* Must set vector notifier after guest notifier has been assigned */
if (kvm_irqchip_in_kernel() && assign) {
proxy->vector_irqfd =
g_malloc0(sizeof(*proxy->vector_irqfd) *
msix_nr_vectors_allocated(&proxy->pci_dev));
r = msix_set_vector_notifiers(&proxy->pci_dev,
kvm_virtio_pci_vector_use,
kvm_virtio_pci_vector_release);
if (r < 0) {
goto assign_error;
}
}
return 0;
assign_error:
/* We get here on assignment failure. Recover by undoing for VQs 0 .. n. */
assert(assign);
while (--n >= 0) {
virtio_pci_set_guest_notifier(opaque, n, !assign);
}

6
hw/virtio-pci.h
View File

@ -24,6 +24,11 @@
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
typedef struct {
int virq;
unsigned int users;
} VirtIOIRQFD;
typedef struct {
PCIDevice pci_dev;
VirtIODevice *vdev;
@ -44,6 +49,7 @@ typedef struct {
VirtIOSCSIConf scsi;
bool ioeventfd_disabled;
bool ioeventfd_started;
VirtIOIRQFD *vector_irqfd;
} VirtIOPCIProxy;
void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev);