Re: [Qemu-devel] [RFC PATCH 2/5] vfio/quirks: Add generic support for ioveventfds

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 8 Feb 2018 12:11:57 +0100
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Alex,
> 
> On 07/02/18 01:26, Alex Williamson wrote:
> > We might wish to handle some quirks via ioeventfds, add a list of
> > ioeventfds to the quirk.  
> The commit title is a bit misleading as we only add the data type and
> deletion function.

Unfortunately that's as much as I can add here or else QEMU will fail
to build because of unused functions :-\  So I pulled as much
infrastructure as I could here but had to leave some meat for when it
gets called.  Suggestions welcome for title/commit updates.

> > 
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> >  hw/vfio/pci-quirks.c |   17 +++++++++++++++++
> >  hw/vfio/pci.h        |   11 +++++++++++
> >  2 files changed, 28 insertions(+)
> > 
> > diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> > index 10af23217292..e4cf4ea2dd9c 100644
> > --- a/hw/vfio/pci-quirks.c
> > +++ b/hw/vfio/pci-quirks.c
> > @@ -12,6 +12,7 @@
> >  
> >  #include "qemu/osdep.h"
> >  #include "qemu/error-report.h"
> > +#include "qemu/main-loop.h"
> >  #include "qemu/range.h"
> >  #include "qapi/error.h"
> >  #include "qapi/visitor.h"
> > @@ -278,12 +279,24 @@ static const MemoryRegionOps vfio_ati_3c3_quirk = {
> >  static VFIOQuirk *vfio_quirk_alloc(int nr_mem)
> >  {
> >      VFIOQuirk *quirk = g_malloc0(sizeof(*quirk));
> > +    QLIST_INIT(&quirk->ioeventfds);
> >      quirk->mem = g_new0(MemoryRegion, nr_mem);
> >      quirk->nr_mem = nr_mem;
> >  
> >      return quirk;
> >  }
> >  
> > +static void vfio_ioeventfd_exit(VFIOIOEventFD *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);
> > +    event_notifier_cleanup(&ioeventfd->e);
> > +    g_free(ioeventfd);
> > +}
> > +
> >  static void vfio_vga_probe_ati_3c3_quirk(VFIOPCIDevice *vdev)
> >  {
> >      VFIOQuirk *quirk;
> > @@ -1668,6 +1681,10 @@ void vfio_bar_quirk_exit(VFIOPCIDevice *vdev, int nr)
> >      int i;
> >  
> >      QLIST_FOREACH(quirk, &bar->quirks, next) {
> > +        while (!QLIST_EMPTY(&quirk->ioeventfds)) {
> > +            vfio_ioeventfd_exit(QLIST_FIRST(&quirk->ioeventfds));
> > +        }
> > +
> >          for (i = 0; i < quirk->nr_mem; i++) {
> >              memory_region_del_subregion(bar->region.mem, &quirk->mem[i]);
> >          }
> > diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
> > index f4aa13e021fa..146065c2f715 100644
> > --- a/hw/vfio/pci.h
> > +++ b/hw/vfio/pci.h
> > @@ -24,9 +24,20 @@
> >  
> >  struct VFIOPCIDevice;
> >  
> > +typedef struct VFIOIOEventFD {
> > +    QLIST_ENTRY(VFIOIOEventFD) next;
> > +    MemoryRegion *mr;
> > +    hwaddr addr;
> > +    unsigned size;
> > +    bool match_data;  
> Shouldn't you add the match_data field also in the kernel uapi?

In the vfio uapi?  vfio isn't matching anything and has no ability to
match anything, it's just triggering a pre-programmed write via
eventfd.  Maybe I'm not understanding the comment.  Thanks,

Alex