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-block-rnbd | 64 ++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-block-rnbd (limited to 'Documentation/ABI/testing/sysfs-block-rnbd') diff --git a/Documentation/ABI/testing/sysfs-block-rnbd b/Documentation/ABI/testing/sysfs-block-rnbd new file mode 100644 index 000000000..80b420b5d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-block-rnbd @@ -0,0 +1,64 @@ +What: /sys/block/rnbd/rnbd/unmap_device +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: To unmap a volume, "normal" or "force" has to be written to: + /sys/block/rnbd/rnbd/unmap_device + + When "normal" is used, the operation will fail with EBUSY if any process + is using the device. When "force" is used, the device is also unmapped + when device is in use. All I/Os that are in progress will fail. + + Example:: + + # echo "normal" > /sys/block/rnbd0/rnbd/unmap_device + +What: /sys/block/rnbd/rnbd/state +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: The file contains the current state of the block device. The state file + returns "open" when the device is successfully mapped from the server + and accepting I/O requests. When the connection to the server gets + disconnected in case of an error (e.g. link failure), the state file + returns "closed" and all I/O requests submitted to it will fail with -EIO. + +What: /sys/block/rnbd/rnbd/session +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: RNBD uses RTRS session to transport the data between client and + server. The entry "session" contains the name of the session, that + was used to establish the RTRS session. It's the same name that + was passed as server parameter to the map_device entry. + +What: /sys/block/rnbd/rnbd/mapping_path +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the path that was passed as "device_path" to the map_device + operation. + +What: /sys/block/rnbd/rnbd/access_mode +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the device access mode: ro, rw or migration. + +What: /sys/block/rnbd/rnbd/resize +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Write the number of sectors to change the size of the disk. + +What: /sys/block/rnbd/rnbd/remap_device +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Remap the disconnected device if the session is not destroyed yet. + +What: /sys/block/rnbd/rnbd/nr_poll_queues +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the number of poll-mode queues -- cgit v1.3.1