On Mon, 2012-05-14 at 13:24 +1000, Alexey Kardashevskiy wrote:
> On 14/05/12 12:55, Alex Williamson wrote:
> > On Sat, 2012-05-12 at 16:50 +1000, Alexey Kardashevskiy wrote:
> >> The original code calculated the real size of the ROM and passed it to
> >> QEMU which tried to do pci_register_bar and failed with error message
> >> "ERROR: PCI region size must be pow2".
> >>
> >> The example card is PCIe Intel E1000E with the ROM size 0x9c00.
> >>
> >> pci_resource_len seems to be a proper solution.
> >>
> >> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> >> ---
> >> drivers/vfio/pci/vfio_pci.c | 9 +++------
> >> 1 files changed, 3 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> >> index b2f1f3a..6d4a783 100644
> >> --- a/drivers/vfio/pci/vfio_pci.c
> >> +++ b/drivers/vfio/pci/vfio_pci.c
> >> @@ -234,12 +234,9 @@ static long vfio_pci_ioctl(void *device_data,
> >> * this gives the user an easy way to determine whether
> >> * there's anything here w/o trying to read it. */
> >
> > This is actually intentional, but maybe isn't the best way to handle it
> > anymore. The cut-off comment above reads:
> >
> > /* Report the actual ROM size instead of the BAR size,
> > * this gives the user an easy way to determine whether
> > * there's anything here w/o trying to read it. */
> >
> > At the time I added that though, I think we still had a separate ioctl
> > to get the BAR size, so one gave the real size, the other the BAR size.
> > Do we care to expose that ROMs have real size, maybe zero, that doesn't
> > necessarily match pci_resource_len()? Thanks,
>
>
> The guest will still see aligned ROM BAR (not real one) and may try to read behind the real end of
> ROM, and it is allowed while it is still within the BAR, right?
Yes.
> >> if (info.index == VFIO_PCI_ROM_REGION_INDEX) {
> >> - void __iomem *io;
> >> - size_t size;
> >> -
> >> - io = pci_map_rom(pdev, &size);
> >> - info.size = io ? size : 0;
> >> - pci_unmap_rom(pdev, io);
> >> + info.size = pci_resource_len(pdev,
> >> + PCI_ROM_RESOURCE);
> >> + info.flags |= VFIO_PCI_ROM_REGION_INDEX;
> >> } else if (flags & IORESOURCE_MEM) {
> >> info.size = pci_resource_len(pdev, info.index);
> >> info.flags |= (VFIO_REGION_INFO_FLAG_WRITE |
> >>
> >
> >
> >
>
>
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