[libvirt] [PATCH 2/2] virpci: support driver_override sysfs interface
Jim Fehlig
jfehlig at suse.com
Mon Jul 11 18:23:20 UTC 2016
Currently, 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
This patch changes the stub binding/unbinding code to use the
driver_override interface if present. If not present, the new_id
interface will be used to provide compatibility with older kernels
lacking driver_override.
Signed-off-by: Jim Fehlig <jfehlig at suse.com>
---
src/util/virpci.c | 199 +++++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 152 insertions(+), 47 deletions(-)
diff --git a/src/util/virpci.c b/src/util/virpci.c
index 127b3b6..3c2fc9f 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1158,6 +1158,19 @@ virPCIDeviceUnbindFromStub(virPCIDevicePtr dev)
VIR_DEBUG("Reprobing for PCI device %s", dev->name);
+ /* Remove driver_override if it exists */
+ VIR_FREE(path);
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ goto cleanup;
+
+ if (virFileExists(path) && virFileWriteStr(path, "\n", 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to remove stub driver from "
+ "driver_override interface of PCI device '%s'"),
+ dev->name);
+ goto cleanup;
+ }
+
/* Trigger a re-probe of the device is not in the stub's dynamic
* ID table. If the stub is available, but 'remove_id' isn't
* available, then re-probing would just cause the device to be
@@ -1193,49 +1206,13 @@ virPCIDeviceUnbindFromStub(virPCIDevicePtr dev)
static int
-virPCIDeviceBindToStub(virPCIDevicePtr dev)
+virPCIDeviceBindToStubWithNewid(virPCIDevicePtr dev,
+ const char *stubDriverName)
{
- int result = -1;
- char *stubDriverPath = NULL;
- char *driverLink = NULL;
- char *path = NULL; /* reused for different purposes */
- const char *stubDriverName = NULL;
+ int ret = -1;
+ char *path = NULL;
virErrorPtr err = 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);
- dev->unbind_from_stub = true;
- dev->remove_slot = true;
- result = 0;
- goto cleanup;
- }
- /*
- * If the device is bound to a driver that is not the stub, we'll
- * need to reprobe later
- */
- dev->reprobe = true;
- }
-
/* Add the PCI device ID to the stub's dynamic ID table;
* this is needed to allow us to bind the device to the stub.
* Note: if the device is not currently bound to any driver,
@@ -1283,7 +1260,7 @@ virPCIDeviceBindToStub(virPCIDevicePtr dev)
}
dev->unbind_from_stub = true;
- result = 0;
+ ret = 0;
remove_id:
err = virSaveLastError();
@@ -1299,7 +1276,7 @@ virPCIDeviceBindToStub(virPCIDevicePtr dev)
"cannot be probed again.", dev->id, stubDriverName);
}
dev->reprobe = false;
- result = -1;
+ ret = -1;
goto cleanup;
}
@@ -1314,11 +1291,143 @@ virPCIDeviceBindToStub(virPCIDevicePtr dev)
"cannot be probed again.", dev->id, stubDriverName);
}
dev->reprobe = false;
- result = -1;
+ ret = -1;
goto cleanup;
}
cleanup:
+ VIR_FREE(path);
+
+ if (err)
+ virSetError(err);
+ virFreeError(err);
+
+ return ret;
+}
+
+
+static int
+virPCIDeviceBindToStubWithOverride(virPCIDevicePtr dev,
+ const char *stubDriverName)
+{
+ int ret = -1;
+ char *path = NULL;
+
+ /*
+ * Add stub to the device's driver_override, falling back to
+ * adding the device ID to the stub's dynamic ID table.
+ */
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ return -1;
+
+ if (virFileWriteStr(path, stubDriverName, 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to add stub driver '%s' to "
+ "driver_override interface of PCI device '%s'"),
+ stubDriverName, dev->name);
+ goto cleanup;
+ }
+
+ if (virPCIDeviceUnbind(dev) < 0)
+ goto cleanup;
+
+ /* Xen's pciback.ko wants you to use new_slot first */
+ VIR_FREE(path);
+ if (!(path = virPCIDriverFile(stubDriverName, "new_slot")))
+ goto cleanup;
+
+ if (virFileExists(path) && virFileWriteStr(path, dev->name, 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to add slot for "
+ "PCI device '%s' to %s"),
+ dev->name, stubDriverName);
+ goto cleanup;
+ }
+ dev->remove_slot = true;
+
+ if (virFileWriteStr(PCI_SYSFS "drivers_probe", dev->name, 0) < 0) {
+ virReportSystemError(errno,
+ _("Failed to trigger a re-probe for PCI device '%s'"),
+ dev->name);
+ goto cleanup;
+ }
+
+ /*
+ * Device is now bound to the stub. Set reprobe so it will be re-bound
+ * when unbinding from the stub.
+ */
+ dev->reprobe = true;
+ dev->unbind_from_stub = true;
+
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(path);
+ return ret;
+}
+
+
+static int
+virPCIDeviceBindToStub(virPCIDevicePtr dev)
+{
+ int result = -1;
+ char *stubDriverPath = NULL;
+ char *driverLink = NULL;
+ char *path = NULL; /* reused for different purposes */
+ const char *stubDriverName = 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);
+ dev->unbind_from_stub = true;
+ dev->remove_slot = true;
+ result = 0;
+ goto cleanup;
+ }
+ /*
+ * If the device is bound to a driver that is not the stub, we'll
+ * need to reprobe later
+ */
+ dev->reprobe = true;
+ }
+
+ /*
+ * Add stub to the device's driver_override, falling back to
+ * adding the device ID to the stub's dynamic ID table.
+ */
+ if (!(path = virPCIFile(dev->name, "driver_override")))
+ goto cleanup;
+
+ if (virFileExists(path)) {
+ if (virPCIDeviceBindToStubWithOverride(dev, stubDriverName) < 0)
+ goto cleanup;
+ } else {
+ if (virPCIDeviceBindToStubWithNewid(dev, stubDriverName) < 0)
+ goto cleanup;
+ }
+
+ result = 0;
+
+ cleanup:
VIR_FREE(stubDriverPath);
VIR_FREE(driverLink);
VIR_FREE(path);
@@ -1326,10 +1435,6 @@ virPCIDeviceBindToStub(virPCIDevicePtr dev)
if (result < 0)
virPCIDeviceUnbindFromStub(dev);
- if (err)
- virSetError(err);
- virFreeError(err);
-
return result;
}
--
2.1.4
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