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vfio/quirks: Enable ioeventfd quirks to be handled by vfio directly
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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%.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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@awilliam
awilliam committed Jun 5, 2018
1 parent c958c51 commit 2b1dbd0
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Showing 4 changed files with 51 additions and 8 deletions.
53 changes: 46 additions & 7 deletions hw/vfio/pci-quirks.c
View file
Expand Up @@ -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"
Expand Down Expand Up @@ -287,12 +288,33 @@ 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)
{
QLIST_REMOVE(ioeventfd, next);
memory_region_del_eventfd(ioeventfd->mr, ioeventfd->addr, ioeventfd->size,
true, ioeventfd->data, &ioeventfd->e);
qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e), NULL, NULL, NULL);

if (ioeventfd->vfio) {
struct vfio_device_ioeventfd vfio_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 = -1;

if (ioctl(vdev->vbasedev.fd, VFIO_DEVICE_IOEVENTFD, &vfio_ioeventfd)) {
error_report("Failed to remove vfio ioeventfd for %s+0x%"
HWADDR_PRIx"[%d]:0x%"PRIx64" (%m)",
memory_region_name(ioeventfd->mr), ioeventfd->addr,
ioeventfd->size, ioeventfd->data);
}
} else {
qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e),
NULL, NULL, NULL);
}

event_notifier_cleanup(&ioeventfd->e);
trace_vfio_ioeventfd_exit(memory_region_name(ioeventfd->mr),
(uint64_t)ioeventfd->addr, ioeventfd->size,
Expand All @@ -306,7 +328,7 @@ static void vfio_drop_dynamic_eventfds(VFIOPCIDevice *vdev, VFIOQuirk *quirk)

QLIST_FOREACH_SAFE(ioeventfd, &quirk->ioeventfds, next, tmp) {
if (ioeventfd->dynamic) {
vfio_ioeventfd_exit(ioeventfd);
vfio_ioeventfd_exit(vdev, ioeventfd);
}
}
}
Expand Down Expand Up @@ -359,12 +381,29 @@ 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);
if (!vdev->no_vfio_ioeventfd) {
struct vfio_device_ioeventfd vfio_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);

ioeventfd->vfio = !ioctl(vdev->vbasedev.fd,
VFIO_DEVICE_IOEVENTFD, &vfio_ioeventfd);
}

if (!ioeventfd->vfio) {
qemu_set_fd_handler(event_notifier_get_fd(&ioeventfd->e),
vfio_ioeventfd_handler, NULL, ioeventfd);
}

memory_region_add_eventfd(ioeventfd->mr, ioeventfd->addr, ioeventfd->size,
true, ioeventfd->data, &ioeventfd->e);
trace_vfio_ioeventfd_init(memory_region_name(mr), (uint64_t)addr,
size, data);
size, data, ioeventfd->vfio);

return ioeventfd;
}
Expand Down Expand Up @@ -1827,7 +1866,7 @@ 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++) {
Expand Down
2 changes: 2 additions & 0 deletions hw/vfio/pci.c
View file
Expand Up @@ -3177,6 +3177,8 @@ static Property vfio_pci_dev_properties[] = {
no_geforce_quirks, false),
DEFINE_PROP_BOOL("x-no-kvm-ioeventfd", VFIOPCIDevice, no_kvm_ioeventfd,
false),
DEFINE_PROP_BOOL("x-no-vfio-ioeventfd", VFIOPCIDevice, no_vfio_ioeventfd,
false),
DEFINE_PROP_UINT32("x-pci-vendor-id", VFIOPCIDevice, vendor_id, PCI_ANY_ID),
DEFINE_PROP_UINT32("x-pci-device-id", VFIOPCIDevice, device_id, PCI_ANY_ID),
DEFINE_PROP_UINT32("x-pci-sub-vendor-id", VFIOPCIDevice,
Expand Down
2 changes: 2 additions & 0 deletions hw/vfio/pci.h
View file
Expand Up @@ -34,6 +34,7 @@ typedef struct VFIOIOEventFD {
VFIORegion *region;
hwaddr region_addr;
bool dynamic; /* Added runtime, removed on device reset */
bool vfio;
} VFIOIOEventFD;

typedef struct VFIOQuirk {
Expand Down Expand Up @@ -163,6 +164,7 @@ typedef struct VFIOPCIDevice {
bool no_kvm_msix;
bool no_geforce_quirks;
bool no_kvm_ioeventfd;
bool no_vfio_ioeventfd;
VFIODisplay *dpy;
} VFIOPCIDevice;

Expand Down
2 changes: 1 addition & 1 deletion hw/vfio/trace-events
View file
Expand Up @@ -79,7 +79,7 @@ vfio_quirk_ati_bonaire_reset_done(const char *name) "%s"
vfio_quirk_ati_bonaire_reset(const char *name) "%s"
vfio_ioeventfd_exit(const char *name, uint64_t addr, unsigned size, uint64_t data) "%s+0x%"PRIx64"[%d]:0x%"PRIx64
vfio_ioeventfd_handler(const char *name, uint64_t addr, unsigned size, uint64_t data) "%s+0x%"PRIx64"[%d] -> 0x%"PRIx64
vfio_ioeventfd_init(const char *name, uint64_t addr, unsigned size, uint64_t data) "%s+0x%"PRIx64"[%d]:0x%"PRIx64
vfio_ioeventfd_init(const char *name, uint64_t addr, unsigned size, uint64_t data, bool vfio) "%s+0x%"PRIx64"[%d]:0x%"PRIx64" vfio:%d"
vfio_pci_igd_bar4_write(const char *name, uint32_t index, uint32_t data, uint32_t base) "%s [0x%03x] 0x%08x -> 0x%08x"
vfio_pci_igd_bdsm_enabled(const char *name, int size) "%s %dMB"
vfio_pci_igd_opregion_enabled(const char *name) "%s"
Expand Down

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