On Wed, 01/10 13:09, Alex Williamson wrote:
> On Wed, 10 Jan 2018 17:18:39 +0800
> Fam Zheng <f...@redhat.com> wrote:
>
> > This is a library to manage the host vfio interface, which could be used
> > to implement userspace device driver code in QEMU such as NVMe or net
> > controllers.
> >
> > Signed-off-by: Fam Zheng <f...@redhat.com>
> > ---
> > include/qemu/vfio-helpers.h | 30 ++
> > util/Makefile.objs | 1 +
> > util/trace-events | 11 +
> > util/vfio-helpers.c | 723
> > ++++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 765 insertions(+)
> > create mode 100644 include/qemu/vfio-helpers.h
> > create mode 100644 util/vfio-helpers.c
> >
> > diff --git a/include/qemu/vfio-helpers.h b/include/qemu/vfio-helpers.h
> > new file mode 100644
> > index 0000000000..6bdba3b66e
> > --- /dev/null
> > +++ b/include/qemu/vfio-helpers.h
> ...
> > +/**
> > + * Map a PCI bar area.
> > + */
> > +void *qemu_vfio_pci_map_bar(QEMUVFIOState *s, int index, Error **errp)
> > +{
> > + void *p;
> > + assert_bar_index_valid(s, index);
> > + p = mmap(NULL, MIN(8192, s->bar_region_info[index].size),
> > + PROT_READ | PROT_WRITE, MAP_SHARED,
> > + s->device, s->bar_region_info[index].offset);
> > + if (p == MAP_FAILED) {
> > + error_setg_errno(errp, errno, "Failed to map BAR region");
> > + p = NULL;
> > + }
> > + return p;
> > +}
> > +
> > +/**
> > + * Unmap a PCI bar area.
> > + */
> > +void qemu_vfio_pci_unmap_bar(QEMUVFIOState *s, int index, void *bar)
> > +{
> > + if (bar) {
> > + munmap(bar, MIN(8192, s->bar_region_info[index].size));
> > + }
> > +}
>
> What's up with this 8KB thing? Is it perhaps a hack to avoid
> un-mmap'able MSI-X sections of the BAR, which would make this general
> purpose library very specific to devices which only operate in the lower
> 8KB of their MMIO space. Maybe the interface should have an offset and
> size so that the NVMe driver could implement that dependency. We could
> also be testing if the region supports mmap, but I suppose trying and
> failing is just as good. Thanks,
Sounds good, will add the offset and size parameters.
Fam
