On Thu, Jan 21, 2010 at 11:33:21AM -0500, Chris Lalancette wrote:
> 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@xxxxxxxxxx>
> ---
> 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
ACK,
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel@xxxxxxxxxxxx | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list