On Mon, 2013-06-03 at 07:28 +0000, Sethi Varun-B16395 wrote:
> > -----Original Message-----
> > From: [email protected] [mailto:iommu-
> > [email protected]] On Behalf Of Alex Williamson
> > Sent: Friday, May 31, 2013 12:09 AM
> > To: [email protected]; [email protected];
> > [email protected]
> > Cc: [email protected]; [email protected]
> > Subject: [PATCH] iommu: amd/intel: Remove multifunction assumption around
> > grouping
> >
> > If a device is multifunction and does not have ACS enabled then we assume
> > that the entire package lacks ACS and use function 0 as the base of the
> > group. The PCIe spec however states that components are permitted to
> > implement ACS on some, none, or all of their applicable functions. It's
> > therefore conceivable that function 0 may be fully independent and
> > support ACS while other functions do not. Instead use the lowest
> > function of the slot that does not have ACS enabled as the base of the
> > group. This may be the current device, which is intentional. So long as
> > we use a consistent algorithm, all the non-ACS functions will be grouped
> > together and ACS functions will get separate groups.
> >
> > Signed-off-by: Alex Williamson <[email protected]>
> > ---
> > drivers/iommu/amd_iommu.c | 25 +++++++++++++++++++------
> > drivers/iommu/intel-iommu.c | 25 +++++++++++++++++++------
> > 2 files changed, 38 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index
> > 1d84be1..565c745 100644
> > --- a/drivers/iommu/amd_iommu.c
> > +++ b/drivers/iommu/amd_iommu.c
> > @@ -287,14 +287,27 @@ static struct pci_dev *get_isolation_root(struct
> > pci_dev *pdev)
> >
> > /*
> > * If it's a multifunction device that does not support our
> > - * required ACS flags, add to the same group as function 0.
> > + * required ACS flags, add to the same group as lowest numbered
> > + * function that also does not suport the required ACS flags.
> > */
> > if (dma_pdev->multifunction &&
> > - !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
> > - swap_pci_ref(&dma_pdev,
> > - pci_get_slot(dma_pdev->bus,
> > - PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
> > - 0)));
> > + !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS)) {
> > + u8 i, slot = PCI_SLOT(dma_pdev->devfn);
> > +
> > + for (i = 0; i < 8; i++) {
> > + struct pci_dev *tmp;
> > +
> > + tmp = pci_get_slot(dma_pdev->bus, PCI_DEVFN(slot, i));
> > + if (!tmp)
> > + continue;
> > +
> > + if (!pci_acs_enabled(tmp, REQ_ACS_FLAGS)) {
> > + swap_pci_ref(&dma_pdev, tmp);
> > + break;
> > + }
> > + pci_dev_put(tmp);
> > + }
> > + }
> >
> > /*
> > * Devices on the root bus go through the iommu. If that's not us,
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index b4f0e28..eec0d3e 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -4182,14 +4182,27 @@ static int intel_iommu_add_device(struct device
> > *dev)
> >
> > /*
> > * If it's a multifunction device that does not support our
> > - * required ACS flags, add to the same group as function 0.
> > + * required ACS flags, add to the same group as lowest numbered
> > + * function that also does not suport the required ACS flags.
> > */
> > if (dma_pdev->multifunction &&
> > - !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
> > - swap_pci_ref(&dma_pdev,
> > - pci_get_slot(dma_pdev->bus,
> > - PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
> > - 0)));
> > + !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS)) {
> > + u8 i, slot = PCI_SLOT(dma_pdev->devfn);
> > +
> > + for (i = 0; i < 8; i++) {
> [Sethi Varun-B16395] A macro like PCI_MAX_FUNCTIONS would improve code
> readability.
Ok, I see a couple defines of PCI_MAX_FUNCTION, I guess we could add one
to iommu/pci.h too.
> > + struct pci_dev *tmp;
> > +
> > + tmp = pci_get_slot(dma_pdev->bus, PCI_DEVFN(slot, i));
> > + if (!tmp)
> > + continue;
> > +
> > + if (!pci_acs_enabled(tmp, REQ_ACS_FLAGS)) {
> > + swap_pci_ref(&dma_pdev, tmp);
> > + break;
> > + }
> > + pci_dev_put(tmp);
> > + }
> > + }
>
> It would be nice if this code could be represented as a function in a common
> file like iommu/pci.c.
I agree, but I haven't gotten any feedback on iommu/pci.c yet and didn't
want this patch to depend on that series. There are probably more
opportunities to consolidate there. Thanks,
Alex
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
