Re: [libvirt] [PATCH v4 03/10] Refuse to reattach from vfio if the iommu group is in use by any domain
On 11/14/2015 03:36 AM, Shivaprasad G Bhat wrote:
Refuse to reattach from vfio if the iommu group is in use by any
domain
util: refuse to reattach device if any device in the same group is in
use by any domain
It is incorrect to attempt the device reattach of a function,
s/function/device/
when some other domain is using some functions belonging to the same
iommu
group.
s/some other domain/any other domain/
s/some functions/any device/
Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com>
---
src/util/virhostdev.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/src/util/virhostdev.c b/src/util/virhostdev.c
index de029a0..f24ccd8 100644
--- a/src/util/virhostdev.c
+++ b/src/util/virhostdev.c
@@ -1590,18 +1590,35 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr
hostdev_mgr,
virPCIDevicePtr pci)
{
virPCIDeviceAddressPtr devAddr = NULL;
+ bool usesVfio = false;
+ char *drvPath = NULL;
+ char *drvName = NULL;
struct virHostdevIsPCINodeDeviceUsedData data = {hostdev_mgr, NULL,
false};
int ret = -1;
+ if (virPCIDeviceGetDriverPathAndName(pci, &drvPath, &drvName) < 0)
+ goto out;
+
+ if (STREQ_NULLABLE(drvName, "vfio-pci"))
+ usesVfio = true;
+
virObjectLock(hostdev_mgr->activePCIHostdevs);
virObjectLock(hostdev_mgr->inactivePCIHostdevs);
if (!(devAddr = virPCIDeviceGetAddress(pci)))
goto out;
- if (virHostdevIsPCINodeDeviceUsed(devAddr, &data))
+ if (usesVfio) {
+ /* Doesn't matter which device. If any domain is actively using the
+ * iommu group, refuse to reattach */
+ if (virPCIDeviceAddressIOMMUGroupIterate(devAddr,
+ virHostdevIsPCINodeDeviceUsed,
+ &data) < 0)
+ goto out;
Calling the iterator seems very inefficient to me (which is why I
suggested in the original BZ comments that we save the iommuGroup of
each device to the activelist):
1) you know the iommu group of the current PCI device (it is in
pci->iommuGroup)
2) all that virHostdevIsPCINodeDeviceUsed does is check through
activePCIHostdevs for the device, and this iterator is just calling
virHostdevIsPCINodeDeviceUsed for each device in the same iommuGroup as
the current device.
Therefore, all you really need to do is look for any devices in
acticePCIHostdevs that have dev->iommuGroup == pci->iommuGroup.
Calling the iterator results in a lot of accesses to sysfs, opening and
closing files, printfs, etc. Unless that is necessary to catch some
extra case (and I don't see that), it's much better to do it the simpler
way - more efficient and easier to understand a year from now when we
come back to this.
+ } else if (virHostdevIsPCINodeDeviceUsed(devAddr, &data)) {
goto out;
+ }
virPCIDeviceReattachInit(pci);
@@ -1614,6 +1631,8 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr hostdev_mgr,
virObjectUnlock(hostdev_mgr->inactivePCIHostdevs);
virObjectUnlock(hostdev_mgr->activePCIHostdevs);
VIR_FREE(devAddr);
+ VIR_FREE(drvPath);
+ VIR_FREE(drvName);
return ret;
}
--
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