Re: [PATCH] pci-assign: Fix multifunction support

Alex Williamson
2012-01-17T13:23:54Z

----- Original Message -----
> On 2012-01-16 18:11, Alex Williamson wrote:
> > The core PCI code sets the multifunction bit in the header before
> > calling the device initfn. For device assignment, we're blasting
> > that value with the actual hardware value, so nobody sees the
> > additional functions if the devices isn't physically multifunction.
> > Switch the HEADER_TYPE to a fully emulated field (all read-only
> > anyway) and add setting and clearing of the multifunction bit to
> > match qemu directive.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> >
> > hw/device-assignment.c | 8 +++++++-
> > 1 files changed, 7 insertions(+), 1 deletions(-)
> >
> > diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> > index 2a9e66d..7f4a5ec 100644
> > --- a/hw/device-assignment.c
> > +++ b/hw/device-assignment.c
> > @@ -540,6 +540,13 @@ again:
> > fprintf(stderr, "%s: read failed, errno = %d\n", __func__,
> > errno);
> > }
> >
> > + /* Restore or clear multifunction, this is always controlled
> > by qemu */
> > + if (pci_dev->dev.cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
> > + pci_dev->dev.config[PCI_HEADER_TYPE] |=
> > PCI_HEADER_TYPE_MULTI_FUNCTION;
> > + } else {
> > + pci_dev->dev.config[PCI_HEADER_TYPE] &=
> > ~PCI_HEADER_TYPE_MULTI_FUNCTION;
> > + }
> > +
>
> Why have this in get_*real*_device? Why not fix this up at the caller
> site, i.e. in assigned_initfn? Just for consistency, not a functional
> issue.

I chose here because we've just overwritten the emulated config space and we then proceed to clean out the BAR registers. As this is close to the point where it gets trashed and we're doing other fixup, it seems appropriate.

> > /* Clear host resource mapping info. If we choose not to
> > register a
> > * BAR, such as might be the case with the option ROM, we can
> > get
> > * confusing, unwritable, residual addresses from the host
> > here. */
> > @@ -1575,7 +1582,6 @@ static int assigned_initfn(struct PCIDevice
> > *pci_dev)
> > assigned_dev_direct_config_read(dev, PCI_CLASS_PROG, 3);
> > assigned_dev_direct_config_read(dev, PCI_CACHE_LINE_SIZE, 1);
> > assigned_dev_direct_config_read(dev, PCI_LATENCY_TIMER, 1);
> > - assigned_dev_direct_config_read(dev, PCI_HEADER_TYPE, 1);
> > assigned_dev_direct_config_read(dev, PCI_BIST, 1);
> > assigned_dev_direct_config_read(dev, PCI_CARDBUS_CIS, 4);
> > assigned_dev_direct_config_read(dev, PCI_SUBSYSTEM_VENDOR_ID,
> > 2);
> >
>
> Looks good otherwise. Is it a regression of the access control
> refactoring?

I believe it's been a latent issue since before the refactoring. Thanks,

Alex