[Xen-devel] [PATCH] pci: treat class 0 devices as endpoints

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Class 0 devices are legacy pre PCI 2.0 devices that didn't have a
class code. Treat them as endpoints, so that they can be handled by
the IOMMU and properly passed-through to the hardware domain.

Such device has been seen on a Super Micro server, lspci -vv reports:

00:13.0 Non-VGA unclassified device: Intel Corporation Device a135 (rev 31)
        Subsystem: Super Micro Computer Inc Device 0931
        Flags: bus master, fast devsel, latency 0, IRQ 11
        Memory at df222000 (64-bit, non-prefetchable) [size=4K]
        Capabilities: [80] Power Management version 3

Arguably this is not a legacy device (since this is a new server), but
in any case Xen needs to deal with it.

Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/drivers/passthrough/pci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 1db69d5b99..c4890a4295 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -927,10 +927,11 @@ enum pdev_type pdev_type(u16 seg, u8 bus, u8 devfn)
     case PCI_CLASS_BRIDGE_HOST:
         return DEV_TYPE_PCI_HOST_BRIDGE;
 
-    case 0x0000: case 0xffff:
+    case 0xffff:
         return DEV_TYPE_PCI_UNKNOWN;
     }
 
+    /* NB: treat legacy pre PCI 2.0 devices (class_device == 0) as endpoints. 
*/
     return pos ? DEV_TYPE_PCIe_ENDPOINT : DEV_TYPE_PCI;
 }
 
-- 
2.17.0


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