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ivshmem: use kvm irqfd for msi notifications 

Use irqfd for improving context switch when notifying the guest.
If the host doesn't support kvm irqfd, regular msi notifications are
still supported.

Note: the ivshmem implementation doesn't allow switching between MSI and
IO interrupts, this patch doesn't either.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marc-André Lureau 2015-07-09 15:50:13 +02:00
parent 0f57350e5c
commit 660c97eef6
1 changed files with 174 additions and 6 deletions
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180
hw/misc/ivshmem.c
View File

@ -19,6 +19,7 @@
#include "hw/hw.h"
#include "hw/i386/pc.h"
#include "hw/pci/pci.h"
#include "hw/pci/msi.h"
#include "hw/pci/msix.h"
#include "sysemu/kvm.h"
#include "migration/migration.h"
@ -68,6 +69,7 @@ typedef struct Peer {
typedef struct MSIVector {
PCIDevice *pdev;
int virq;
} MSIVector;
typedef struct IVShmemState {
@ -293,13 +295,73 @@ static void fake_irqfd(void *opaque, const uint8_t *buf, int size) {
msix_notify(pdev, vector);
}
static int ivshmem_vector_unmask(PCIDevice *dev, unsigned vector,
MSIMessage msg)
{
IVShmemState *s = IVSHMEM(dev);
EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
MSIVector *v = &s->msi_vectors[vector];
int ret;
IVSHMEM_DPRINTF("vector unmask %p %d\n", dev, vector);
ret = kvm_irqchip_update_msi_route(kvm_state, v->virq, msg, dev);
if (ret < 0) {
return ret;
}
return kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, n, NULL, v->virq);
}
static void ivshmem_vector_mask(PCIDevice *dev, unsigned vector)
{
IVShmemState *s = IVSHMEM(dev);
EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
int ret;
IVSHMEM_DPRINTF("vector mask %p %d\n", dev, vector);
ret = kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n,
s->msi_vectors[vector].virq);
if (ret != 0) {
error_report("remove_irqfd_notifier_gsi failed");
}
}
static void ivshmem_vector_poll(PCIDevice *dev,
unsigned int vector_start,
unsigned int vector_end)
{
IVShmemState *s = IVSHMEM(dev);
unsigned int vector;
IVSHMEM_DPRINTF("vector poll %p %d-%d\n", dev, vector_start, vector_end);
vector_end = MIN(vector_end, s->vectors);
for (vector = vector_start; vector < vector_end; vector++) {
EventNotifier *notifier = &s->peers[s->vm_id].eventfds[vector];
if (!msix_is_masked(dev, vector)) {
continue;
}
if (event_notifier_test_and_clear(notifier)) {
msix_set_pending(dev, vector);
}
}
}
static CharDriverState* create_eventfd_chr_device(void * opaque, EventNotifier *n,
int vector)
{
/* create a event character device based on the passed eventfd */
IVShmemState *s = opaque;
CharDriverState * chr;
PCIDevice *pdev = PCI_DEVICE(s);
int eventfd = event_notifier_get_fd(n);
CharDriverState *chr;
s->msi_vectors[vector].pdev = pdev;
chr = qemu_chr_open_eventfd(eventfd);
@ -484,6 +546,58 @@ static bool fifo_update_and_get(IVShmemState *s, const uint8_t *buf, int size,
return true;
}
static int ivshmem_add_kvm_msi_virq(IVShmemState *s, int vector)
{
PCIDevice *pdev = PCI_DEVICE(s);
MSIMessage msg = msix_get_message(pdev, vector);
int ret;
IVSHMEM_DPRINTF("ivshmem_add_kvm_msi_virq vector:%d\n", vector);
if (s->msi_vectors[vector].pdev != NULL) {
return 0;
}
ret = kvm_irqchip_add_msi_route(kvm_state, msg, pdev);
if (ret < 0) {
error_report("ivshmem: kvm_irqchip_add_msi_route failed");
return -1;
}
s->msi_vectors[vector].virq = ret;
s->msi_vectors[vector].pdev = pdev;
return 0;
}
static void setup_interrupt(IVShmemState *s, int vector)
{
EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
bool with_irqfd = kvm_msi_via_irqfd_enabled() &&
ivshmem_has_feature(s, IVSHMEM_MSI);
PCIDevice *pdev = PCI_DEVICE(s);
IVSHMEM_DPRINTF("setting up interrupt for vector: %d\n", vector);
if (!with_irqfd) {
IVSHMEM_DPRINTF("with eventfd");
s->eventfd_chr[vector] = create_eventfd_chr_device(s, n, vector);
} else if (msix_enabled(pdev)) {
IVSHMEM_DPRINTF("with irqfd");
if (ivshmem_add_kvm_msi_virq(s, vector) < 0) {
return;
}
if (!msix_is_masked(pdev, vector)) {
kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, n, NULL,
s->msi_vectors[vector].virq);
}
} else {
/* it will be delayed until msix is enabled, in write_config */
IVSHMEM_DPRINTF("with irqfd, delayed until msix enabled");
}
}
static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
{
IVShmemState *s = opaque;
@ -586,11 +700,10 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
IVSHMEM_DPRINTF("eventfds[%ld][%d] = %d\n", incoming_posn,
new_eventfd, incoming_fd);
event_notifier_init_fd(&peer->eventfds[new_eventfd], incoming_fd);
fcntl_setfl(incoming_fd, O_NONBLOCK); /* msix/irqfd poll non block */
if (incoming_posn == s->vm_id) {
s->eventfd_chr[new_eventfd] = create_eventfd_chr_device(s,
&s->peers[s->vm_id].eventfds[new_eventfd],
new_eventfd);
setup_interrupt(s, new_eventfd);
}
if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
@ -665,10 +778,65 @@ static int ivshmem_setup_msi(IVShmemState * s)
return 0;
}
static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
static void ivshmem_enable_irqfd(IVShmemState *s)
{
PCIDevice *pdev = PCI_DEVICE(s);
int i;
for (i = 0; i < s->peers[s->vm_id].nb_eventfds; i++) {
ivshmem_add_kvm_msi_virq(s, i);
}
if (msix_set_vector_notifiers(pdev,
ivshmem_vector_unmask,
ivshmem_vector_mask,
ivshmem_vector_poll)) {
error_report("ivshmem: msix_set_vector_notifiers failed");
}
}
static void ivshmem_remove_kvm_msi_virq(IVShmemState *s, int vector)
{
IVSHMEM_DPRINTF("ivshmem_remove_kvm_msi_virq vector:%d\n", vector);
if (s->msi_vectors[vector].pdev == NULL) {
return;
}
/* it was cleaned when masked in the frontend. */
kvm_irqchip_release_virq(kvm_state, s->msi_vectors[vector].virq);
s->msi_vectors[vector].pdev = NULL;
}
static void ivshmem_disable_irqfd(IVShmemState *s)
{
PCIDevice *pdev = PCI_DEVICE(s);
int i;
for (i = 0; i < s->peers[s->vm_id].nb_eventfds; i++) {
ivshmem_remove_kvm_msi_virq(s, i);
}
msix_unset_vector_notifiers(pdev);
}
static void ivshmem_write_config(PCIDevice *pdev, uint32_t address,
uint32_t val, int len)
{
pci_default_write_config(pci_dev, address, val, len);
IVShmemState *s = IVSHMEM(pdev);
int is_enabled, was_enabled = msix_enabled(pdev);
pci_default_write_config(pdev, address, val, len);
is_enabled = msix_enabled(pdev);
if (kvm_msi_via_irqfd_enabled() && s->vm_id != -1) {
if (!was_enabled && is_enabled) {
ivshmem_enable_irqfd(s);
} else if (was_enabled && !is_enabled) {
ivshmem_disable_irqfd(s);
}
}
}
static void pci_ivshmem_realize(PCIDevice *dev, Error **errp)