With vfio ioeventfd support, we can program vfio-pci to perform a
specified BAR write when an eventfd is triggered. This allows the
KVM ioeventfd to be wired directly to vfio-pci, entirely avoiding
userspace handling for these events. On the same micro-benchmark
where the ioeventfd got us to almost 90% of performance versus
disabling the GeForce quirks, this gets us to within 95%.
Signed-off-by: Alex Williamson <alex.william...@redhat.com>
---
hw/vfio/pci-quirks.c | 42 ++++++++++++++++++++++++++++++++++++------
1 file changed, 36 insertions(+), 6 deletions(-)
diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index e739efe601b1..35a4d5197e2d 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -16,6 +16,7 @@
#include "qemu/range.h"
#include "qapi/error.h"
#include "qapi/visitor.h"
+#include <sys/ioctl.h>
#include "hw/nvram/fw_cfg.h"
#include "pci.h"
#include "trace.h"
@@ -287,13 +288,27 @@ static VFIOQuirk *vfio_quirk_alloc(int nr_mem)
return quirk;
}
-static void vfio_ioeventfd_exit(VFIOIOEventFD *ioeventfd)
+static void vfio_ioeventfd_exit(VFIOPCIDevice *vdev, VFIOIOEventFD *ioeventfd)
{
+ struct vfio_device_ioeventfd vfio_ioeventfd;
+
QLIST_REMOVE(ioeventfd, next);
+
memory_region_del_eventfd(ioeventfd->mr, ioeventfd->addr, ioeventfd->size,
ioeventfd->match_data, ioeventfd->data,
&ioeventfd->e);
+
qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e), NULL, NULL,
NULL);
+
+ vfio_ioeventfd.argsz = sizeof(vfio_ioeventfd);
+ vfio_ioeventfd.flags = ioeventfd->size;
+ vfio_ioeventfd.data = ioeventfd->data;
+ vfio_ioeventfd.offset = ioeventfd->region->fd_offset +
+ ioeventfd->region_addr;
+ vfio_ioeventfd.fd = -1;
+
+ ioctl(vdev->vbasedev.fd, VFIO_DEVICE_IOEVENTFD, &vfio_ioeventfd);
+
event_notifier_cleanup(&ioeventfd->e);
g_free(ioeventfd);
}
@@ -315,6 +330,8 @@ static VFIOIOEventFD *vfio_ioeventfd_init(VFIOPCIDevice
*vdev,
hwaddr region_addr)
{
VFIOIOEventFD *ioeventfd = g_malloc0(sizeof(*ioeventfd));
+ struct vfio_device_ioeventfd vfio_ioeventfd;
+ char vfio_enabled = '+';
if (event_notifier_init(&ioeventfd->e, 0)) {
g_free(ioeventfd);
@@ -329,15 +346,28 @@ static VFIOIOEventFD *vfio_ioeventfd_init(VFIOPCIDevice
*vdev,
ioeventfd->region = region;
ioeventfd->region_addr = region_addr;
- qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e),
- vfio_ioeventfd_handler, NULL, ioeventfd);
+ vfio_ioeventfd.argsz = sizeof(vfio_ioeventfd);
+ vfio_ioeventfd.flags = ioeventfd->size;
+ vfio_ioeventfd.data = ioeventfd->data;
+ vfio_ioeventfd.offset = ioeventfd->region->fd_offset +
+ ioeventfd->region_addr;
+ vfio_ioeventfd.fd = event_notifier_get_fd(&ioeventfd->e);
+
+ if (ioctl(vdev->vbasedev.fd,
+ VFIO_DEVICE_IOEVENTFD, &vfio_ioeventfd) != 0) {
+ qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e),
+ vfio_ioeventfd_handler, NULL, ioeventfd);
+ vfio_enabled = '-';
+ }
+
memory_region_add_eventfd(ioeventfd->mr, ioeventfd->addr,
ioeventfd->size, ioeventfd->match_data,
ioeventfd->data, &ioeventfd->e);
info_report("Enabled automatic ioeventfd acceleration for %s region %d, "
- "offset 0x%"HWADDR_PRIx", data 0x%"PRIx64", size %u",
- vdev->vbasedev.name, region->nr, region_addr, data, size);
+ "offset 0x%"HWADDR_PRIx", data 0x%"PRIx64", size %u, vfio%c",
+ vdev->vbasedev.name, region->nr, region_addr, data, size,
+ vfio_enabled);
return ioeventfd;
}
@@ -1767,7 +1797,7 @@ void vfio_bar_quirk_exit(VFIOPCIDevice *vdev, int nr)
QLIST_FOREACH(quirk, &bar->quirks, next) {
while (!QLIST_EMPTY(&quirk->ioeventfds)) {
- vfio_ioeventfd_exit(QLIST_FIRST(&quirk->ioeventfds));
+ vfio_ioeventfd_exit(vdev, QLIST_FIRST(&quirk->ioeventfds));
}
for (i = 0; i < quirk->nr_mem; i++) {
