KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rapidio b/Documentation/ABI/testing/sysfs-class-rapidio
new file mode 100644
index 000000000..81e091455
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-rapidio
@@ -0,0 +1,59 @@
+What:		/sys/class/rapidio_port
+Description:
+		On-chip RapidIO controllers and PCIe-to-RapidIO bridges
+		(referenced as "Master Port" or "mport") are presented in sysfs
+		as the special class of devices: "rapidio_port".
+		The /sys/class/rapidio_port subdirectory contains individual
+		subdirectories named as "rapidioN" where N = mport ID registered
+		with RapidIO subsystem.
+
+		NOTE: An mport ID is not a RapidIO destination ID assigned to a
+		given local mport device.
+
+What:		/sys/class/rapidio_port/rapidio<N>/sys_size
+Date:		Apr, 2014
+KernelVersion:	v3.15
+Contact:	Matt Porter <mporter@kernel.crashing.org>,
+		Alexandre Bounine <alexandre.bounine@idt.com>
+Description:
+		(RO) reports RapidIO common transport system size:
+
+		0 = small (8-bit destination ID, max. 256 devices),
+
+		1 = large (16-bit destination ID, max. 65536 devices).
+
+What:		/sys/class/rapidio_port/rapidio<N>/port_destid
+Date:		Apr, 2014
+KernelVersion:	v3.15
+Contact:	Matt Porter <mporter@kernel.crashing.org>,
+		Alexandre Bounine <alexandre.bounine@idt.com>
+Description:
+
+(RO) reports RapidIO destination ID assigned to the given
+RapidIO mport device. If value 0xFFFFFFFF is returned this means
+that no valid destination ID have been assigned to the mport
+(yet). Normally, before enumeration/discovery have been executed
+only fabric enumerating mports have a valid destination ID
+assigned to them using "hdid=..." rapidio module parameter.
+
+After enumeration or discovery was performed for a given mport device,
+the corresponding subdirectory will also contain subdirectories for each
+child RapidIO device connected to the mport.
+
+The example below shows mport device subdirectory with several child RapidIO
+devices attached to it::
+
+    [rio@rapidio ~]$ ls /sys/class/rapidio_port/rapidio0/ -l
+    total 0
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0001
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0004
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0007
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0002
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0003
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0005
+    lrwxrwxrwx 1 root root    0 Feb 11 15:11 device -> ../../../0000:01:00.0
+    -r--r--r-- 1 root root 4096 Feb 11 15:11 port_destid
+    drwxr-xr-x 2 root root    0 Feb 11 15:11 power
+    lrwxrwxrwx 1 root root    0 Feb 11 15:04 subsystem -> ../../../../../../class/rapidio_port
+    -r--r--r-- 1 root root 4096 Feb 11 15:11 sys_size
+    -rw-r--r-- 1 root root 4096 Feb 11 15:04 uevent