[libvirt] [PATCH] Fix device assignment with root devices
The patches to add ACS checking to PCI device passthrough
introduced a bug. With the current code, if you try to
passthrough a device on the root bus (i.e. bus 0), then
it denies the passthrough. This is because the code in
pciDeviceIsBehindSwitchLackingACS() to check for a parent
device doesn't take into account the possibility of the
root bus. If we are on the root bus, it means we
legitimately can't find a parent, and it also means that
we don't have to worry about whether ACS is enabled.
Therefore return 0 (indicating we don't lack ACS) from
pciDeviceIsBehindSwitchLackingACS().
Signed-off-by: Chris Lalancette <clalance(a)redhat.com>
---
src/util/pci.c | 19 ++++++++++++++-----
1 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/src/util/pci.c b/src/util/pci.c
index 086b751..0defbfe 100644
--- a/src/util/pci.c
+++ b/src/util/pci.c
@@ -1198,11 +1198,20 @@ pciDeviceIsBehindSwitchLackingACS(virConnectPtr conn,
{
pciDevice *parent;
- if (!(parent = pciGetParentDevice(conn, dev))) {
- pciReportError(conn, VIR_ERR_NO_SUPPORT,
- _("Failed to find parent device for %s"),
- dev->name);
- return -1;
+ parent = pciGetParentDevice(conn, dev);
+ if (!parent) {
+ /* if we have no parent, and this is the root bus, ACS doesn't come
+ * into play since devices on the root bus can't P2P without going
+ * through the root IOMMU.
+ */
+ if (dev->bus == 0)
+ return 0;
+ else {
+ pciReportError(conn, VIR_ERR_NO_SUPPORT,
+ _("Failed to find parent device for %s"),
+ dev->name);
+ return -1;
+ }
}
/* XXX we should rather fail when we can't find device's parent and
--
1.6.6