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Re: [Qemu-devel] [PATCH v2 4/4] vfio/quirks: Enable ioeventfd quirks to
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [PATCH v2 4/4] vfio/quirks: Enable ioeventfd quirks to be handled by vfio directly |
Date: |
Thu, 3 May 2018 10:30:34 -0600 |
On Thu, 3 May 2018 17:20:18 +0200
Auger Eric <address@hidden> wrote:
> Hi Alex,
>
> On 05/01/2018 06:43 PM, Alex Williamson wrote:
> > 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 <address@hidden>
> > ---
> > hw/vfio/pci-quirks.c | 50
> > +++++++++++++++++++++++++++++++++++++++++++-------
> > hw/vfio/pci.c | 2 ++
> > hw/vfio/pci.h | 2 ++
> > hw/vfio/trace-events | 2 +-
> > 4 files changed, 48 insertions(+), 8 deletions(-)
> >
> > diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> > index 4cedc733bc0a..94be27dd0a3b 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 +288,31 @@ 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);
> > +
> nit: unrelated new line
Fixed
> > 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);
> > +
> > + 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;
> > +
> > + ioctl(vdev->vbasedev.fd, VFIO_DEVICE_IOEVENTFD, &vfio_ioeventfd);
> > +
> > + } 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,
> > @@ -307,7 +326,7 @@ 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);
> > }
> > }
> > }
> > @@ -361,13 +380,30 @@ 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, ioeventfd->match_data,
> > ioeventfd->data, &ioeventfd->e);
> > trace_vfio_ioeventfd_init(memory_region_name(mr), (uint64_t)addr,
> > - size, data);
> > + size, data, ioeventfd->vfio);
> >
> > return ioeventfd;
> > }
> > @@ -1835,7 +1871,7 @@ 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++) {
> > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > index ba1239551115..84e27c7bb2d1 100644
> > --- a/hw/vfio/pci.c
> > +++ b/hw/vfio/pci.c
> > @@ -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),
> I tend to agree with Peter about the 2 options. Only the KVM
> acceleration brings benefit here?
Consolidated response in reply to Peter. Thanks,
Alex