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, 27 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing b/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing
new file mode 100644
index 000000000..910df0e58
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing
@@ -0,0 +1,27 @@
+What:		/sys/bus/platform/drivers/aspeed-uart-routing/\*/uart\*
+Date:		September 2021
+Contact:	Oskar Senft <osk@google.com>
+		Chia-Wei Wang <chiawei_wang@aspeedtech.com>
+Description:	Selects the RX source of the UARTx device.
+
+		When read, each file shows the list of available options with currently
+		selected option marked by brackets "[]". The list of available options
+		depends on the selected file.
+
+		e.g.
+		cat /sys/bus/platform/drivers/aspeed-uart-routing/\*.uart_routing/uart1
+		[io1] io2 io3 io4 uart2 uart3 uart4 io6
+
+		In this case, UART1 gets its input from IO1 (physical serial port 1).
+
+Users:		OpenBMC.  Proposed changes should be mailed to
+		openbmc@lists.ozlabs.org
+
+What:		/sys/bus/platform/drivers/aspeed-uart-routing/\*/io\*
+Date:		September 2021
+Contact:	Oskar Senft <osk@google.com>
+		Chia-Wei Wang <chiawei_wang@aspeedtech.com>
+Description:	Selects the RX source of IOx serial port. The current selection
+		will be marked by brackets "[]".
+Users:		OpenBMC.  Proposed changes should be mailed to
+		openbmc@lists.ozlabs.org