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, 21 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-mmc b/Documentation/ABI/testing/sysfs-devices-mmc
new file mode 100644
index 000000000..5a50ab655
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-mmc
@@ -0,0 +1,21 @@
+What:		/sys/devices/.../mmc_host/mmcX/mmcX:XXXX/enhanced_area_offset
+Date:		January 2011
+Contact:	Chuanxiao Dong <chuanxiao.dong@intel.com>
+Description:
+		Enhanced area is a new feature defined in eMMC4.4 standard.
+		eMMC4.4 or later card can support such feature. This kind of
+		area can help to improve the card performance. If the feature
+		is enabled, this attribute will indicate the start address of
+		enhanced data area. If not, this attribute will be -EINVAL.
+		Unit Byte. Format decimal.
+
+What:		/sys/devices/.../mmc_host/mmcX/mmcX:XXXX/enhanced_area_size
+Date:		January 2011
+Contact:	Chuanxiao Dong <chuanxiao.dong@intel.com>
+Description:
+		Enhanced area is a new feature defined in eMMC4.4 standard.
+		eMMC4.4 or later card can support such feature. This kind of
+		area can help to improve the card performance. If the feature
+		is enabled, this attribute will indicate the size of enhanced
+		data area. If not, this attribute will be -EINVAL.
+		Unit KByte. Format decimal.