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, 106 insertions, 0 deletions

diff --git a/drivers/hid/hid-viewsonic.c b/drivers/hid/hid-viewsonic.c
new file mode 100644
index 000000000..532bed88b
--- /dev/null
+++ b/drivers/hid/hid-viewsonic.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  HID driver for ViewSonic devices not fully compliant with HID standard
+ *
+ *  Copyright (c) 2017 Nikolai Kondrashov
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/* Size of the original descriptor of PD1011 signature pad */
+#define PD1011_RDESC_ORIG_SIZE	408
+
+/* Fixed report descriptor of PD1011 signature pad */
+static const __u8 pd1011_rdesc_fixed[] = {
+	0x05, 0x0D,             /*  Usage Page (Digitizer),             */
+	0x09, 0x01,             /*  Usage (Digitizer),                  */
+	0xA1, 0x01,             /*  Collection (Application),           */
+	0x85, 0x02,             /*      Report ID (2),                  */
+	0x09, 0x20,             /*      Usage (Stylus),                 */
+	0xA0,                   /*      Collection (Physical),          */
+	0x75, 0x10,             /*          Report Size (16),           */
+	0x95, 0x01,             /*          Report Count (1),           */
+	0xA4,                   /*          Push,                       */
+	0x05, 0x01,             /*          Usage Page (Desktop),       */
+	0x65, 0x13,             /*          Unit (Inch),                */
+	0x55, 0xFD,             /*          Unit Exponent (-3),         */
+	0x34,                   /*          Physical Minimum (0),       */
+	0x09, 0x30,             /*          Usage (X),                  */
+	0x46, 0x5D, 0x21,       /*          Physical Maximum (8541),    */
+	0x27, 0x80, 0xA9,
+		0x00, 0x00,     /*          Logical Maximum (43392),    */
+	0x81, 0x02,             /*          Input (Variable),           */
+	0x09, 0x31,             /*          Usage (Y),                  */
+	0x46, 0xDA, 0x14,       /*          Physical Maximum (5338),    */
+	0x26, 0xF0, 0x69,       /*          Logical Maximum (27120),    */
+	0x81, 0x02,             /*          Input (Variable),           */
+	0xB4,                   /*          Pop,                        */
+	0x14,                   /*          Logical Minimum (0),        */
+	0x25, 0x01,             /*          Logical Maximum (1),        */
+	0x75, 0x01,             /*          Report Size (1),            */
+	0x95, 0x01,             /*          Report Count (1),           */
+	0x81, 0x03,             /*          Input (Constant, Variable), */
+	0x09, 0x32,             /*          Usage (In Range),           */
+	0x09, 0x42,             /*          Usage (Tip Switch),         */
+	0x95, 0x02,             /*          Report Count (2),           */
+	0x81, 0x02,             /*          Input (Variable),           */
+	0x95, 0x05,             /*          Report Count (5),           */
+	0x81, 0x03,             /*          Input (Constant, Variable), */
+	0x75, 0x10,             /*          Report Size (16),           */
+	0x95, 0x01,             /*          Report Count (1),           */
+	0x09, 0x30,             /*          Usage (Tip Pressure),       */
+	0x15, 0x05,             /*          Logical Minimum (5),        */
+	0x26, 0xFF, 0x07,       /*          Logical Maximum (2047),     */
+	0x81, 0x02,             /*          Input (Variable),           */
+	0x75, 0x10,             /*          Report Size (16),           */
+	0x95, 0x01,             /*          Report Count (1),           */
+	0x81, 0x03,             /*          Input (Constant, Variable), */
+	0xC0,                   /*      End Collection,                 */
+	0xC0                    /*  End Collection                      */
+};
+
+static const __u8 *viewsonic_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+					  unsigned int *rsize)
+{
+	switch (hdev->product) {
+	case USB_DEVICE_ID_VIEWSONIC_PD1011:
+	case USB_DEVICE_ID_SIGNOTEC_VIEWSONIC_PD1011:
+		if (*rsize == PD1011_RDESC_ORIG_SIZE) {
+			*rsize = sizeof(pd1011_rdesc_fixed);
+			return pd1011_rdesc_fixed;
+		}
+		break;
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id viewsonic_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_VIEWSONIC,
+				USB_DEVICE_ID_VIEWSONIC_PD1011) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SIGNOTEC,
+				USB_DEVICE_ID_SIGNOTEC_VIEWSONIC_PD1011) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, viewsonic_devices);
+
+static struct hid_driver viewsonic_driver = {
+	.name = "viewsonic",
+	.id_table = viewsonic_devices,
+	.report_fixup = viewsonic_report_fixup,
+};
+module_hid_driver(viewsonic_driver);
+
+MODULE_DESCRIPTION("HID driver for ViewSonic devices not fully compliant with HID standard");
+MODULE_LICENSE("GPL");