On 08/01/2016 11:36 PM, Jim Fehlig wrote:
libvirt uses the new_id PCI sysfs interface to bind a PCI stub driver
to a PCI device. The new_id interface is known to be buggy and racey,
hence a more deterministic interface was introduced in the 3.12 kernel:
driver_override. For more details see
https://www.redhat.com/archives/libvir-list/2016-June/msg02124.html
That message details the change to the kernel that caused the regression
for Xen, but not the driver_override interface. Maybe you could add a
link to the kernel commit that adds driver_override:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/pci/pci-driver.c?h=v3.12&id=782a985d7af26db39e86070d28f987cad21313c0
Everything else looks good, and passes my tests for vfio device
assignment (including when the host driver has been blacklisted).
ACK. (Sorry I forgot about this earlier in the month :-/)
This patch adds support for the driver_override interface by
- adding new virPCIDevice{BindTo,UnbindFrom}StubWithOverride functions
that use the driver_override interface
- renames the existing virPCIDevice{BindTo,UnbindFrom}Stub functions
to virPCIDevice{BindTo,UnbindFrom}StubWithNewid to perserve existing
behavior on new_id interface
- changes virPCIDevice{BindTo,UnbindFrom}Stub function to call one of
the above depending on availability of driver_override
The patch includes a bit of duplicate code, but allows for easily
dropping the new_id code once support for older kernels is no
longer desired.
Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
V1:
https://www.redhat.com/archives/libvir-list/2016-July/msg00370.html
Changes since V1:
- drop patch1
- change patch2 to preserve the existing new_id code and add new
functions to implement the driver_override interface
src/util/virpci.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 149 insertions(+), 2 deletions(-)
diff --git a/src/util/virpci.c b/src/util/virpci.c
index 132948d..6c8174a 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1089,8 +1089,54 @@ virPCIDeviceUnbind(virPCIDevicePtr dev)
return ret;
}
+/*
+ * Bind a PCI device to a driver using driver_override sysfs interface.
+ * E.g.
+ *
+ * echo driver-name > /sys/bus/pci/devices/0000:03:00.0/driver_override
+ * echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind
+ * echo 0000:03:00.0 > /sys/bus/pci/drivers_probe
+ *
+ * An empty driverName will cause the device to be bound to its
+ * preferred driver.
+ */
static int
-virPCIDeviceUnbindFromStub(virPCIDevicePtr dev)
+virPCIDeviceBindWithDriverOverride(virPCIDevicePtr dev,
+ const char *driverName)
+{
+ int ret = -1;
+ char *path;
+
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ return -1;
+
+ if (virFileWriteStr(path, driverName, 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to add driver '%s' to driver_override "
+ " interface of PCI device '%s'"),
+ driverName, dev->name);
+ goto cleanup;
+ }
+
+ if (virPCIDeviceUnbind(dev) < 0)
+ goto cleanup;
+
+ if (virFileWriteStr(PCI_SYSFS "drivers_probe", dev->name, 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to trigger a probe for PCI device '%s'"),
+ dev->name);
+ goto cleanup;
+ }
+
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(path);
+ return ret;
+}
+
+static int
+virPCIDeviceUnbindFromStubWithNewid(virPCIDevicePtr dev)
{
int result = -1;
char *drvdir = NULL;
@@ -1191,9 +1237,41 @@ virPCIDeviceUnbindFromStub(virPCIDevicePtr dev)
return result;
}
+static int
+virPCIDeviceUnbindFromStubWithOverride(virPCIDevicePtr dev)
+{
+ if (!dev->unbind_from_stub) {
+ VIR_DEBUG("Unbind from stub skipped for PCI device %s", dev->name);
+ return 0;
+ }
+
+ return virPCIDeviceBindWithDriverOverride(dev, "\n");
+}
+
+static int
+virPCIDeviceUnbindFromStub(virPCIDevicePtr dev)
+{
+ int ret;
+ char *path;
+
+ /*
+ * Prefer using the device's driver_override interface, falling back
+ * to the unpleasant new_id interface.
+ */
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ return -1;
+
+ if (virFileExists(path))
+ ret = virPCIDeviceUnbindFromStubWithOverride(dev);
+ else
+ ret = virPCIDeviceUnbindFromStubWithNewid(dev);
+
+ VIR_FREE(path);
+ return ret;
+}
static int
-virPCIDeviceBindToStub(virPCIDevicePtr dev)
+virPCIDeviceBindToStubWithNewid(virPCIDevicePtr dev)
{
int result = -1;
bool reprobe = false;
@@ -1345,6 +1423,75 @@ virPCIDeviceBindToStub(virPCIDevicePtr dev)
return result;
}
+static int
+virPCIDeviceBindToStubWithOverride(virPCIDevicePtr dev)
+{
+ int ret = -1;
+ const char *stubDriverName;
+ char *stubDriverPath = NULL;
+ char *driverLink = NULL;
+
+ /* Check the device is configured to use one of the known stub drivers */
+ if (dev->stubDriver == VIR_PCI_STUB_DRIVER_NONE) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("No stub driver configured for PCI device %s"),
+ dev->name);
+ return -1;
+ } else if (!(stubDriverName = virPCIStubDriverTypeToString(dev->stubDriver))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Unknown stub driver configured for PCI device %s"),
+ dev->name);
+ return -1;
+ }
+
+ if (!(stubDriverPath = virPCIDriverDir(stubDriverName)) ||
+ !(driverLink = virPCIFile(dev->name, "driver")))
+ goto cleanup;
+
+ if (virFileExists(driverLink)) {
+ if (virFileLinkPointsTo(driverLink, stubDriverPath)) {
+ /* The device is already bound to the correct driver */
+ VIR_DEBUG("Device %s is already bound to %s",
+ dev->name, stubDriverName);
+ ret = 0;
+ goto cleanup;
+ }
+ }
+
+ if (virPCIDeviceBindWithDriverOverride(dev, stubDriverName) < 0)
+ goto cleanup;
+
+ dev->unbind_from_stub = true;
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(stubDriverPath);
+ VIR_FREE(driverLink);
+ return ret;
+}
+
+static int
+virPCIDeviceBindToStub(virPCIDevicePtr dev)
+{
+ int ret;
+ char *path;
+
+ /*
+ * Prefer using the device's driver_override interface, falling back
+ * to the unpleasant new_id interface.
+ */
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ return -1;
+
+ if (virFileExists(path))
+ ret = virPCIDeviceBindToStubWithOverride(dev);
+ else
+ ret = virPCIDeviceBindToStubWithNewid(dev);
+
+ VIR_FREE(path);
+ return ret;
+}
+
/* virPCIDeviceDetach:
*
* Detach this device from the host driver, attach it to the stub
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list