From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- Documentation/ABI/testing/sysfs-bus-vfio-mdev | 113 ++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-vfio-mdev (limited to 'Documentation/ABI/testing/sysfs-bus-vfio-mdev') diff --git a/Documentation/ABI/testing/sysfs-bus-vfio-mdev b/Documentation/ABI/testing/sysfs-bus-vfio-mdev new file mode 100644 index 000000000..59fc80426 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-vfio-mdev @@ -0,0 +1,113 @@ +What: /sys/...//mdev_supported_types/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains list of directories of currently + supported mediated device types and their details for + . Supported type attributes are defined by the + vendor driver who registers with Mediated device framework. + Each supported type is a directory whose name is created + by adding the device driver string as a prefix to the + string provided by the vendor driver. + +What: /sys/...//mdev_supported_types// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory gives details of supported type, like name, + description, available_instances, device_api etc. + 'device_api' and 'available_instances' are mandatory + attributes to be provided by vendor driver. 'name', + 'description' and other vendor driver specific attributes + are optional. + +What: /sys/.../mdev_supported_types//create +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing UUID to this file will create mediated device of + type for parent device . This is a + write-only file. + For example:: + + # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \ + /sys/devices/foo/mdev_supported_types/foo-1/create + +What: /sys/.../mdev_supported_types//devices/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains symbolic links pointing to mdev + devices sysfs entries which are created of this . + +What: /sys/.../mdev_supported_types//available_instances +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show the number of mediated + devices of type that can be created. This is a + readonly file. +Users: + Userspace applications interested in creating mediated + device of that type. Userspace application should check + the number of available instances could be created before + creating mediated device of this type. + +What: /sys/.../mdev_supported_types//device_api +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show VFIO device API supported + by this type. For example, "vfio-pci" for a PCI device, + "vfio-platform" for platform device. + +What: /sys/.../mdev_supported_types//name +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show human readable name of the + mediated device that will get created of type . + This is optional attribute. For example: "Grid M60-0Q" +Users: + Userspace applications interested in knowing the name of + a particular that can help in understanding the + type of mediated device. + +What: /sys/.../mdev_supported_types//description +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show description of the type of + mediated device that will get created of type . + This is optional attribute. For example: + "2 heads, 512M FB, 2560x1600 maximum resolution" +Users: + Userspace applications interested in knowing the details of + a particular that can help in understanding the + features provided by that type of mediated device. + +What: /sys/.../// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory represents device directory of mediated + device. It contains all the attributes related to mediated + device. + +What: /sys/...///mdev_type +Date: October 2016 +Contact: Kirti Wankhede +Description: + This is symbolic link pointing to supported type, + directory of which this mediated device is created. + +What: /sys/...///remove +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing '1' to this file destroys the mediated device. The + vendor driver can fail the remove() callback if that device + is active and the vendor driver doesn't support hot unplug. + Example:: + + # echo 1 > /sys/bus/mdev/devices//remove -- cgit v1.3.1