8:10 a.m.
Add code to check availability of PCI passhthrough using VFIO and the
legacy KVM passthrough and use it when starting VMs and hotplugging
devices to live machine.
---
Notes:
Version 2:
- Merge of multiple patches from v1 posting
- changed +qemuHostdevHostSupportsPassthrough*() to static
- added function splitting out common parts of the code between machine start and
hotplug
src/qemu/qemu_hostdev.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++++
src/qemu/qemu_hostdev.h | 4 ++
src/qemu/qemu_hotplug.c | 4 ++
src/qemu/qemu_process.c | 4 ++
4 files changed, 138 insertions(+)
diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c
index 21fe47f..dbbc2b4 100644
--- a/src/qemu/qemu_hostdev.c
+++ b/src/qemu/qemu_hostdev.c
@@ -23,6 +23,11 @@
#include <config.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+
#include "qemu_hostdev.h"
#include "virlog.h"
#include "virerror.h"
@@ -31,6 +36,7 @@
#include "virusb.h"
#include "virscsi.h"
#include "virnetdev.h"
+#include "virfile.h"
#define VIR_FROM_THIS VIR_FROM_QEMU
@@ -1287,3 +1293,123 @@ void qemuDomainReAttachHostDevices(virQEMUDriverPtr driver,
qemuDomainReAttachHostScsiDevices(driver, def->name, def->hostdevs,
def->nhostdevs);
}
+
+
+static bool
+qemuHostdevHostSupportsPassthroughVFIO(void)
+{
+ DIR *iommuDir = NULL;
+ struct dirent *iommuGroup = NULL;
+ bool ret = false;
+
+ /* condition 1 - /sys/kernel/iommu_groups/ contains entries */
+ if (!(iommuDir = opendir("/sys/kernel/iommu_groups/")))
+ goto cleanup;
+
+ while ((iommuGroup = readdir(iommuDir))) {
+ /* skip ./ ../ */
+ if (STRPREFIX(iommuGroup->d_name, "."))
+ continue;
+
+ /* assume we found a group */
+ break;
+ }
+
+ if (!iommuGroup)
+ goto cleanup;
+ /* okay, iommu is on and recognizes groups */
+
+ /* condition 2 - /dev/vfio/vfio exists */
+ if (!virFileExists("/dev/vfio/vfio"))
+ goto cleanup;
+
+ ret = true;
+
+cleanup:
+ if (iommuDir)
+ closedir(iommuDir);
+
+ return ret;
+}
+
+
+#if HAVE_LINUX_KVM_H
+# include <linux/kvm.h>
+static bool
+qemuHostdevHostSupportsPassthroughLegacy(void)
+{
+ int kvmfd = -1;
+ bool ret = false;
+
+ if ((kvmfd = open("/dev/kvm", O_RDONLY)) < 0)
+ goto cleanup;
+
+# ifdef KVM_CAP_IOMMU
+ if ((ioctl(kvmfd, KVM_CHECK_EXTENSION, KVM_CAP_IOMMU)) <= 0)
+ goto cleanup;
+
+ ret = true;
+# endif
+
+cleanup:
+ VIR_FORCE_CLOSE(kvmfd);
+
+ return ret;
+}
+#else
+static bool
+qemuHostdevHostSupportsPassthroughLegacy(void)
+{
+ return false;
+}
+#endif
+
+bool
+qemuHostdevHostVerifySupport(virDomainHostdevDefPtr *hostdevs,
+ size_t nhostdevs)
+{
+ int supportsPassthroughKVM = -1;
+ int supportsPassthroughVFIO = -1;
+ size_t i;
+
+ /* assign defaults for hostdev passthrough */
+ for (i = 0; i < nhostdevs; i++) {
+ virDomainHostdevDefPtr hostdev = hostdevs[i];
+
+ if (hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
+ hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI) {
+ int *backend = &hostdev->source.subsys.u.pci.backend;
+
+ /* cache host state of passthrough support */
+ if (supportsPassthroughKVM == -1 || supportsPassthroughVFIO == -1) {
+ supportsPassthroughKVM = qemuHostdevHostSupportsPassthroughLegacy();
+ supportsPassthroughVFIO = qemuHostdevHostSupportsPassthroughVFIO();
+ }
+
+ switch ((virDomainHostdevSubsysPciBackendType) *backend) {
+ case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO:
+ if (!supportsPassthroughVFIO) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("host doesn't support VFIO PCI
passthrough"));
+ return false;
+ }
+ break;
+
+ case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:
+ case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM:
+ if (!supportsPassthroughKVM) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("host doesn't support legacy PCI
passthrough"));
+ return false;
+ }
+
+ break;
+
+ case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST:
+ break;
+ }
+ }
+ }
+
+ return true;
+}
diff --git a/src/qemu/qemu_hostdev.h b/src/qemu/qemu_hostdev.h
index 327d4d5..6d88830 100644
--- a/src/qemu/qemu_hostdev.h
+++ b/src/qemu/qemu_hostdev.h
@@ -69,4 +69,8 @@ int qemuDomainHostdevNetConfigReplace(virDomainHostdevDefPtr hostdev,
int qemuDomainHostdevNetConfigRestore(virDomainHostdevDefPtr hostdev,
char *stateDir);
+bool qemuHostdevHostVerifySupport(virDomainHostdevDefPtr *hostdevs,
+ size_t nhostdevs);
+
+
#endif /* __QEMU_HOSTDEV_H__ */
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 728c734..604a0ed 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1143,6 +1143,10 @@ int qemuDomainAttachHostPciDevice(virQEMUDriverPtr driver,
&hostdev, 1) < 0)
return -1;
+ /* verify the availability of passthrough support */
+ if (!qemuHostdevHostVerifySupport(&hostdev, 1))
+ goto error;
+
switch ((virDomainHostdevSubsysPciBackendType) *backend) {
case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO:
if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index dd16f6c..baf021f 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3713,6 +3713,10 @@ int qemuProcessStart(virConnectPtr conn,
goto cleanup;
}
+ /* check and assign device assignment settings */
+ if (!qemuHostdevHostVerifySupport(vm->def->hostdevs,
vm->def->nhostdevs))
+ goto cleanup;
+
/*
* Normally PCI addresses are assigned in the virDomainCreate
* or virDomainDefine methods. We might still need to assign
--
1.8.3.2