[libvirt] [PATCH 9/9] Wait for iommmu device to go away before reprobing the host driver
There could be a delay of 1 or 2 seconds before the vfio-pci driver
is unbound and the device file /dev/vfio/<iommu> is actually
removed. If the file exists, the host driver probing the device
can lead to crash. So, wait and avoid the crash.
Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com>
---
src/util/virpci.c | 41 +++++++++++++++++++++++++++++++++++++++++
tests/virpcimock.c | 14 ++++++++++++--
2 files changed, 53 insertions(+), 2 deletions(-)
diff --git a/src/util/virpci.c b/src/util/virpci.c
index caa2458..157327f 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1098,6 +1098,43 @@ virPCIIsKnownStub(char *driver)
return ret;
}
+#define VFIO_UNBIND_TIMEOUT 100
+
+/* It is not safe to initiate host driver probe if the vfio driver has not
+ * completely unbound the device. Usual wait time is 1 to 2 seconds.
+ * So, return if the unbind didn't complete in 10 seconds.
+ */
+static int
+virPCIWaitForVFIOUnbindCompletion(virPCIDevicePtr dev)
+{
+ int retry = 0;
+ int ret = -1;
+ char *path = NULL;
+
+ if (!(path = virPCIDeviceGetIOMMUGroupDev(dev)))
+ goto cleanup;
+
+ while (retry++ < VFIO_UNBIND_TIMEOUT) {
+ if (!virFileExists(path))
+ break;
+ usleep(100000); /* Sleep for 1/10th of a second */
+ }
+
+ if (virFileExists(path)) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("VFIO unbind not completed even after %d seconds"
+ " for device %s"), retry, dev->name);
+ goto cleanup;
+ }
+
+ ret = 0;
+ cleanup:
+ VIR_FREE(path);
+ return ret;
+
+}
+
+
static int
virPCIDeviceReprobeHostDriver(virPCIDevicePtr dev,
const char *driver,
@@ -1275,6 +1312,10 @@ virPCIDeviceUnbindFromStub(virPCIDevicePtr dev,
/* This device is the last to unbind from vfio. As we explicitly
* add a missing device in the list to inactiveList, we will just
* go through the list. */
+
+ if (virPCIWaitForVFIOUnbindCompletion(dev) < 0)
+ goto cleanup;
+
while (inactiveDevs && (i < virPCIDeviceListCount(inactiveDevs))) {
virPCIDevicePtr pcidev = virPCIDeviceListGet(inactiveDevs, i);
if (dev->iommuGroup == pcidev->iommuGroup) {
diff --git a/tests/virpcimock.c b/tests/virpcimock.c
index 926a548..9ee46d9 100644
--- a/tests/virpcimock.c
+++ b/tests/virpcimock.c
@@ -52,6 +52,7 @@ static DIR * (*realopendir)(const char *name);
char *fakesysfsdir;
# define PCI_SYSFS_PREFIX "/sys/bus/pci/"
+# define ROOT_DEV_PREFIX "/dev/"
# define STDERR(...) \
fprintf(stderr, "%s %zu: ", __FUNCTION__, (size_t) __LINE__); \
@@ -248,6 +249,13 @@ getrealpath(char **newpath,
errno = ENOMEM;
return -1;
}
+ } else if (STRPREFIX(path, ROOT_DEV_PREFIX)) {
+ if (virAsprintfQuiet(newpath, "%s/%s",
+ fakesysfsdir,
+ path) < 0) {
+ errno = ENOMEM;
+ return -1;
+ }
} else {
if (VIR_STRDUP_QUIET(*newpath, path) < 0)
return -1;
@@ -995,7 +1003,8 @@ access(const char *path, int mode)
init_syms();
- if (STRPREFIX(path, PCI_SYSFS_PREFIX)) {
+ if (STRPREFIX(path, PCI_SYSFS_PREFIX) ||
+ STRPREFIX(path, ROOT_DEV_PREFIX)) {
char *newpath;
if (getrealpath(&newpath, path) < 0)
return -1;
@@ -1014,7 +1023,8 @@ __lxstat(int ver, const char *path, struct stat *sb)
init_syms();
- if (STRPREFIX(path, PCI_SYSFS_PREFIX)) {
+ if (STRPREFIX(path, PCI_SYSFS_PREFIX) ||
+ STRPREFIX(path, ROOT_DEV_PREFIX)) {
char *newpath;
if (getrealpath(&newpath, path) < 0)
return -1;