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, 75 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-ppi b/Documentation/ABI/testing/sysfs-driver-ppi
new file mode 100644
index 000000000..1a56fc507
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-ppi
@@ -0,0 +1,75 @@
+What:		/sys/class/tpm/tpmX/ppi/
+Date:		August 2012
+KernelVersion:	3.6
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This folder includes the attributes related with PPI (Physical
+		Presence Interface). Only if TPM is supported by BIOS, this
+		folder makes sense. The folder path can be got by command
+		'find /sys/ -name 'pcrs''. For the detail information of PPI,
+		please refer to the PPI specification from
+
+		http://www.trustedcomputinggroup.org/
+
+		In Linux 4.2 ppi was moved to the character device directory.
+		A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
+		compatibility.
+
+What:		/sys/class/tpm/tpmX/ppi/version
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the version of the PPI supported by the
+		platform.
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/request
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the request for an operation to be
+		executed in the pre-OS environment. It is the only input from
+		the OS to the pre-OS environment. The request should be an
+		integer value range from 1 to 160, and 0 means no request.
+		This file can be read and written.
+
+What:		/sys/class/tpm/tpmX/ppi/response
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the response to the most recent operation
+		request it acted upon. The format is "<request> <response num>
+		: <response description>".
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/transition_action
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the platform-specific action that should
+		take place in order to transition to the BIOS for execution of
+		a requested operation. The format is "<action num>: <action
+		description>".
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/tcg_operations
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows whether it is allowed to request an
+		operation to be executed in the pre-OS environment by the BIOS
+		for the requests defined by TCG, i.e. requests from 1 to 22.
+		The format is "<request> <status num>: <status description>".
+		This attribute is only supported by PPI version 1.2+.
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/vs_operations
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows whether it is allowed to request an
+		operation to be executed in the pre-OS environment by the BIOS
+		for the verdor specific requests, i.e. requests from 128 to
+		255. The format is same with tcg_operations. This attribute
+		is also only supported by PPI version 1.2+.
+		This file is readonly.