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, 97 insertions, 0 deletions

diff --git a/drivers/firmware/qcom/Kconfig b/drivers/firmware/qcom/Kconfig
new file mode 100644
index 000000000..c7f8413ab
--- /dev/null
+++ b/drivers/firmware/qcom/Kconfig
@@ -0,0 +1,97 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# For a description of the syntax of this configuration file,
+# see Documentation/kbuild/kconfig-language.rst.
+#
+
+menu "Qualcomm firmware drivers"
+
+config QCOM_PAS
+	tristate "Qualcomm generic PAS interface driver"
+	help
+	  Enable the generic Peripheral Authentication Service (PAS) provided
+	  by the firmware. It acts as the common layer with different TZ
+	  backends plugged in whether it's an SCM implementation or a proper
+	  TEE bus based PAS service implementation.
+
+config QCOM_PAS_TEE
+	tristate "Qualcomm PAS TEE interface driver"
+	select QCOM_PAS
+	depends on TEE
+	depends on !CPU_BIG_ENDIAN
+	default m if ARCH_QCOM
+	help
+	  Enable the generic Peripheral Authentication Service (PAS) provided
+	  by the firmware TEE implementation as the backend.
+
+config QCOM_SCM
+	tristate "Qualcomm PAS SCM interface driver"
+	select QCOM_PAS
+	select QCOM_TZMEM
+	default y if ARCH_QCOM
+
+config QCOM_TZMEM
+	tristate
+	select GENERIC_ALLOCATOR
+
+choice
+	prompt "TrustZone interface memory allocator mode"
+	depends on QCOM_TZMEM
+	default QCOM_TZMEM_MODE_GENERIC
+	help
+	  Selects the mode of the memory allocator providing memory buffers of
+	  suitable format for sharing with the TrustZone. If in doubt, select
+	  'Generic'.
+
+config QCOM_TZMEM_MODE_GENERIC
+	bool "Generic"
+	help
+	  Use the generic allocator mode. The memory is page-aligned, non-cachable
+	  and physically contiguous.
+
+config QCOM_TZMEM_MODE_SHMBRIDGE
+	bool "SHM Bridge"
+	help
+	  Use Qualcomm Shared Memory Bridge. The memory has the same alignment as
+	  in the 'Generic' allocator but is also explicitly marked as an SHM Bridge
+	  buffer.
+
+	  With this selected, all buffers passed to the TrustZone must be allocated
+	  using the TZMem allocator or else the TrustZone will refuse to use them.
+
+endchoice
+
+config QCOM_QSEECOM
+	bool "Qualcomm QSEECOM interface driver"
+	depends on QCOM_SCM=y
+	select AUXILIARY_BUS
+	help
+	  Various Qualcomm SoCs have a Secure Execution Environment (SEE) running
+	  in the Trust Zone. This module provides an interface to that via the
+	  QSEECOM mechanism, using SCM calls.
+
+	  The QSEECOM interface allows, among other things, access to applications
+	  running in the SEE. An example of such an application is 'uefisecapp',
+	  which is required to access UEFI variables on certain systems. If
+	  selected, the interface will also attempt to detect and register client
+	  devices for supported applications.
+
+	  Select Y here to enable the QSEECOM interface driver.
+
+config QCOM_QSEECOM_UEFISECAPP
+	bool "Qualcomm SEE UEFI Secure App client driver"
+	depends on QCOM_QSEECOM
+	depends on EFI
+	help
+	  Various Qualcomm SoCs do not allow direct access to EFI variables.
+	  Instead, these need to be accessed via the UEFI Secure Application
+	  (uefisecapp), residing in the Secure Execution Environment (SEE).
+
+	  This module provides a client driver for uefisecapp, installing efivar
+	  operations to allow the kernel accessing EFI variables, and via that also
+	  provide user-space with access to EFI variables via efivarfs.
+
+	  Select Y here to provide access to EFI variables on the aforementioned
+	  platforms.
+
+endmenu