[PATCH v4] VT-d: fix VF of RC integrated PF matched to wrong VT-d unit

[Chao Gao <chao.gao@intel.com>]

The problem is for a VF of RC integrated PF (e.g. PF's BDF is 00:02.0),
we would wrongly use 00:00.0 to search VT-d unit.

From SRIOV spec REV 1.0 section 3.7.3, it says:
"ARI is not applicable to Root Complex integrated Endpoints; all other
SR-IOV Capable Devices (Devices that include at least one PF) shall
implement the ARI Capability in each Function.". So PFs can be classified to
two kinds: one is RC integrated PF and the other is non-RC integrated PF. The
former can't support ARI and the latter shall support ARI. For Extended
Functions, one traditional function's BDF should be used to search VT-d unit.
And according to PCIe spec, Extened Function means within an ARI device, a
Function whose Function Number is greater than 7. Thus, the former can't be an
extended function, while the latter is as long as its devfn > 7, this check is
exactly what the original code did; The original code wasn't aware the former.

This patch directly looks up the 'is_extfn' field of PF's struct pci_dev
to decide whether the PF is a extended function.

Reported-by: Crawford, Eric R <Eric.R.Crawford@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
---
v3:
 - access pf's struct pci_pdev between pcidevs_lock() and pcidevs_unlock()
---
 xen/drivers/passthrough/vtd/dmar.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/vtd/dmar.c b/xen/drivers/passthrough/vtd/dmar.c
index 82040dd..27ff471 100644
--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -218,8 +218,17 @@ struct acpi_drhd_unit *acpi_find_matched_drhd_unit(const struct pci_dev *pdev)
     }
     else if ( pdev->info.is_virtfn )
     {
+        struct pci_dev *physfn;
+
         bus = pdev->info.physfn.bus;
-        devfn = PCI_SLOT(pdev->info.physfn.devfn) ? 0 : pdev->info.physfn.devfn;
+        /*
+         * Use 0 as 'devfn' to search VT-d unit when the physical function
+         * is an Extended Function.
+         */
+        pcidevs_lock();
+        physfn = pci_get_pdev(pdev->seg, bus, pdev->info.physfn.devfn);
+        devfn = (physfn && physfn->info.is_extfn) ? 0 : pdev->info.physfn.devfn;
+        pcidevs_unlock();
     }
     else
     {
-- 
1.8.3.1


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