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, 77 insertions, 0 deletions

diff --git a/drivers/usb/usbip/Kconfig b/drivers/usb/usbip/Kconfig
new file mode 100644
index 000000000..50945b6fa
--- /dev/null
+++ b/drivers/usb/usbip/Kconfig
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config USBIP_CORE
+	tristate "USB/IP support"
+	depends on NET
+	select USB_COMMON
+	select SGL_ALLOC
+	help
+	  This enables pushing USB packets over IP to allow remote
+	  machines direct access to USB devices. It provides the
+	  USB/IP core that is required by both drivers.
+
+	  For more details, and to get the userspace utility
+	  programs, please see <http://usbip.sourceforge.net/>.
+
+	  To compile this as a module, choose M here: the module will
+	  be called usbip-core.
+
+	  If unsure, say N.
+
+config USBIP_VHCI_HCD
+	tristate "VHCI hcd"
+	depends on USBIP_CORE && USB
+	help
+	  This enables the USB/IP virtual host controller driver,
+	  which is run on the remote machine.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called vhci-hcd.
+
+config USBIP_VHCI_HC_PORTS
+	int "Number of ports per USB/IP virtual host controller"
+	range 1 15
+	default 8
+	depends on USBIP_VHCI_HCD
+	help
+	  To increase number of ports available for USB/IP virtual
+	  host controller driver, this defines number of ports per
+	  USB/IP virtual host controller.
+
+config USBIP_VHCI_NR_HCS
+	int "Number of USB/IP virtual host controllers"
+	range 1 32
+	default 1
+	depends on USBIP_VHCI_HCD
+	help
+	  To increase number of ports available for USB/IP virtual
+	  host controller driver, this defines number of USB/IP
+	  virtual host controllers as if adding physical host
+	  controllers.
+
+config USBIP_HOST
+	tristate "Host driver"
+	depends on USBIP_CORE && USB
+	help
+	  This enables the USB/IP host driver, which is run on the
+	  machine that is sharing the USB devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbip-host.
+
+config USBIP_VUDC
+	tristate "VUDC driver"
+	depends on USBIP_CORE && USB_GADGET
+	help
+	  This enables the USB/IP virtual USB device controller
+	  driver, which is run on the host machine, allowing the
+	  machine itself to act as a device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbip-vudc.
+
+config USBIP_DEBUG
+	bool "Debug messages for USB/IP"
+	depends on USBIP_CORE
+	help
+	  This enables the debug messages from the USB/IP drivers.