On 07/29/2016 11:43 AM, Laine Stump wrote:
On 07/11/2016 02:23 PM, Jim Fehlig wrote:
> 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(a)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;
> + }
> +
For unbinding the stub, you're just adding in the "clearing" of
driver_override, without eliminating any of the other stuff that's done for
the older deprecated method. If the driver_override file exists, you shouldn't
do *any* of the old operations, just do what is described in the commit log
message of the patch that added driver_override to the kernel:
https://www.redhat.com/archives/libvir-list/2014-May/msg00670.html
I'll review the rest of it based on what ends up in the code rather than the
diffs, since the diffs will be messed up when you get rid of patch 1/2...
Yeah, I was trying to shoehorn this in the existing code, which we have found to
be unwise.
> /* 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;
What is this "new_slot" stuff all about? Are you certain that it's still
needed when using driver_override, or is it just some lore from the old method
that isn't needed anymore? (I'm unable to test this because I don't have a
host with Xen). The only things that should be needed are:
I was certain it was needed in my last round of testing, but while working on V2
I've found it is unnecessary.
1) write the stub driver name to driver_override
2) write the device's PCI address to driver/unbind
3) write the device's PCI address to /sys/bus/pci/drivers_probe.
(As a matter of fact, it's exactly the same operation as when binding back to
the host driver, just the string written to driver_override changes, so there
should probably be a common routine that takes the driver name as an argument
- maybe just add driverName to this function and rename it?).
Good suggestion. I've incorporated it into V2
https://www.redhat.com/archives/libvir-list/2016-August/msg00087.html
Regards,
Jim