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, 29 insertions, 0 deletions

diff --git a/drivers/usb/roles/Kconfig b/drivers/usb/roles/Kconfig
new file mode 100644
index 000000000..f8b31aa67
--- /dev/null
+++ b/drivers/usb/roles/Kconfig
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config USB_ROLE_SWITCH
+	tristate "USB Role Switch Support"
+	help
+	  USB Role Switch is a device that can select the USB role - host or
+	  device - for a USB port (connector). In most cases dual-role capable
+	  USB controller will also represent the switch, but on some platforms
+	  multiplexer/demultiplexer switch is used to route the data lines on
+	  the USB connector between separate USB host and device controllers.
+
+	  Say Y here if your USB connectors support both device and host roles.
+	  To compile the driver as module, choose M here: the module will be
+	  called roles.ko.
+
+if USB_ROLE_SWITCH
+
+config USB_ROLES_INTEL_XHCI
+	tristate "Intel XHCI USB Role Switch"
+	depends on ACPI && X86
+	help
+	  Driver for the internal USB role switch for switching the USB data
+	  lines between the xHCI host controller and the dwc3 gadget controller
+	  found on various Intel SoCs.
+
+	  To compile the driver as a module, choose M here: the module will
+	  be called intel-xhci-usb-role-switch.
+
+endif # USB_ROLE_SWITCH