@@ -1589,10 +1589,12 @@ backend driver in domain 0 rather than a real driver.
=item B<pci-assignable-add> I<BDF>
Make the device at PCI Bus/Device/Function BDF assignable to guests.
-This will bind the device to the pciback driver. If it is already
-bound to a driver, it will first be unbound, and the original driver
-stored so that it can be re-bound to the same driver later if desired.
-If the device is already bound, it will return success.
+This will bind the device to the pciback driver and assign it to the
+"quarantine domain". If it is already bound to a driver, it will
+first be unbound, and the original driver stored so that it can be
+re-bound to the same driver later if desired. If the device is
+already bound, it will assign it to the quarantine domain and return
+success.
CAUTION: This will make the device unusable by Domain 0 until it is
returned with pci-assignable-remove. Care should therefore be taken
@@ -1602,11 +1604,22 @@ being used.
=item B<pci-assignable-remove> [I<-r>] I<BDF>
-Make the device at PCI Bus/Device/Function BDF not assignable to guests. This
-will at least unbind the device from pciback. If the -r option is specified,
-it will also attempt to re-bind the device to its original driver, making it
-usable by Domain 0 again. If the device is not bound to pciback, it will
-return success.
+Make the device at PCI Bus/Device/Function BDF not assignable to
+guests. This will at least unbind the device from pciback, and
+re-assign it from the "quarantine domain" back to domain 0. If the -r
+option is specified, it will also attempt to re-bind the device to its
+original driver, making it usable by Domain 0 again. If the device is
+not bound to pciback, it will return success.
+
+Note that this functionality will work even for devices which were not
+made assignable by B<pci-assignable-add>. This can be used to allow
+dom0 to access devices which were automatically quarantined by Xen
+after domain destruction as a result of Xen's B<iommu=quarantine>
+command-line default.
+
+As always, this should only be done if you trust the guest, or are
+confident that the particular device you're re-assigning to dom0 will
+cancel all in-flight DMA on FLR.
=item B<pci-attach> I<domain-id> I<BDF>
Changesets 319f9a0ba9 ("passthrough: quarantine PCI devices") and ba2ab00bbb ("IOMMU: default to always quarantining PCI devices") introduced PCI device "quarantine" behavior, but did not document how the pci-assignable-add and -remove functions act in regard to this. Rectify this. Signed-off-by: George Dunlap <george.dunlap@citrix.com> Release-acked-by: Juergen Gross <jgross@suse.com> --- Release justification: This brings documentation into line with the actual code that will be released. CC: Ian Jackson <ian.jackson@citrix.com> CC: Wei Liu <wl@xen.org> CC: Jan Beulich <jbeulich@suse.com> CC: Paul Durrant <paul@xen.org> CC: Juergen Gross <jgross@suse.com> --- docs/man/xl.1.pod.in | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-)