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, 95 insertions, 0 deletions

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
new file mode 100644
index 000000000..a7144d275
--- /dev/null
+++ b/drivers/video/Kconfig
@@ -0,0 +1,95 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Video configuration
+#
+
+menu "Graphics support"
+
+config APERTURE_HELPERS
+	bool
+	help
+	  Support tracking and hand-over of aperture ownership. Required
+	  by graphics drivers for firmware-provided framebuffers.
+
+config SCREEN_INFO
+	bool
+	default n
+
+config STI_CORE
+	bool
+	depends on PARISC
+	help
+	  STI refers to the HP "Standard Text Interface" which is a set of
+	  BIOS routines contained in a ROM chip in HP PA-RISC based machines.
+
+config VIDEO
+	bool
+	default n
+
+source "drivers/auxdisplay/Kconfig"
+
+if HAS_IOMEM
+
+config HAVE_FB_ATMEL
+	bool
+
+source "drivers/char/agp/Kconfig"
+
+source "drivers/gpu/vga/Kconfig"
+
+source "drivers/gpu/Kconfig"
+source "drivers/gpu/host1x/Kconfig"
+source "drivers/gpu/ipu-v3/Kconfig"
+source "drivers/gpu/nova-core/Kconfig"
+
+source "drivers/gpu/drm/Kconfig"
+
+menu "Frame buffer Devices"
+source "drivers/video/fbdev/Kconfig"
+endmenu
+
+source "drivers/video/backlight/Kconfig"
+
+config VGASTATE
+       tristate
+       default n
+
+config VIDEOMODE_HELPERS
+	bool
+
+config HDMI
+	bool
+
+endif # HAS_IOMEM
+
+config FIRMWARE_EDID
+	bool "Enable firmware EDID"
+	depends on EFI_GENERIC_STUB || X86
+	help
+	  This enables access to the EDID transferred from the firmware.
+	  On EFI systems, the EDID comes from the same device as the
+	  primary GOP. On x86 with BIOS, it comes from the VESA BIOS.
+	  DRM display drivers will be able to export the information
+	  to userspace.
+
+	  Also enable this if DDC/I2C transfers do not work for your driver
+	  and if you are using nvidiafb, i810fb or savagefb.
+
+	  In general, choosing Y for this option is safe.  If you
+	  experience extremely long delays while booting before you get
+	  something on your display, try setting this to N.  Matrox cards in
+	  combination with certain motherboards and monitors are known to
+	  suffer from this problem.
+
+if VT
+	source "drivers/video/console/Kconfig"
+endif
+
+if FB_CORE || SGI_NEWPORT_CONSOLE
+	source "drivers/video/logo/Kconfig"
+
+endif
+
+source "drivers/gpu/trace/Kconfig"
+
+endmenu