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, 166 insertions, 0 deletions

diff --git a/drivers/hid/hid-maltron.c b/drivers/hid/hid-maltron.c
new file mode 100644
index 000000000..f0aad1ba2
--- /dev/null
+++ b/drivers/hid/hid-maltron.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID driver for Maltron L90
+ *
+ * Copyright (c) 1999 Andreas Gal
+ * Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ * Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ * Copyright (c) 2008 Jiri Slaby
+ * Copyright (c) 2012 David Dillow <dave@thedillows.org>
+ * Copyright (c) 2006-2013 Jiri Kosina
+ * Copyright (c) 2013 Colin Leitner <colin.leitner@gmail.com>
+ * Copyright (c) 2014-2016 Frank Praznik <frank.praznik@gmail.com>
+ * Copyright (c) 2010 Richard Nauber <Richard.Nauber@gmail.com>
+ * Copyright (c) 2016 Yuxuan Shui <yshuiv7@gmail.com>
+ * Copyright (c) 2018 William Whistler <wtbw@wtbw.co.uk>
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/* The original buggy USB descriptor */
+static const u8 maltron_rdesc_o[] = {
+	0x05, 0x01,        /* Usage Page (Generic Desktop Ctrls) */
+	0x09, 0x80,        /* Usage (Sys Control)                */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x02,        /*   Report ID (2)                    */
+	0x75, 0x01,        /*   Report Size (1)                  */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x15, 0x00,        /*   Logical Minimum (0)              */
+	0x25, 0x01,        /*   Logical Maximum (1)              */
+	0x09, 0x82,        /*   Usage (Sys Sleep)                */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x09, 0x82,        /*   Usage (Sys Sleep)                */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x09, 0x83,        /*   Usage (Sys Wake Up)              */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x75, 0x05,        /*   Report Size (5)                  */
+	0x81, 0x01,        /*   Input (Const,Array,Abs)          */
+	0xC0,              /* End Collection                     */
+	0x05, 0x0C,        /* Usage Page (Consumer)              */
+	0x09, 0x01,        /* Usage (Consumer Control)           */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x03,        /*   Report ID (3)                    */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x75, 0x10,        /*   Report Size (16)                 */
+	0x19, 0x00,        /*   Usage Minimum (Unassigned)       */
+	0x2A, 0xFF, 0x7F,  /*   Usage Maximum (0x7FFF)           */
+	0x81, 0x00,        /*   Input (Data,Array,Abs)           */
+	0xC0,              /* End Collection                     */
+	0x06, 0x7F, 0xFF,  /* Usage Page (Vendor Defined 0xFF7F) */
+	0x09, 0x01,        /* Usage (0x01)                       */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x04,        /*   Report ID (4)                    */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x75, 0x10,        /*   Report Size (16)                 */
+	0x19, 0x00,        /*   Usage Minimum (0x00)             */
+	0x2A, 0xFF, 0x7F,  /*   Usage Maximum (0x7FFF)           */
+	0x81, 0x00,        /*   Input (Data,Array,Abs)           */
+	0x75, 0x02,        /*   Report Size (2)                  */
+	0x25, 0x02,        /*   Logical Maximum (2)              */
+	0x09, 0x90,        /*   Usage (0x90)                     */
+	0xB1, 0x02,        /*   Feature (Data,Var,Abs)           */
+	0x75, 0x06,        /*   Report Size (6)                  */
+	0xB1, 0x01,        /*   Feature (Const,Array,Abs)        */
+	0x75, 0x01,        /*   Report Size (1)                  */
+	0x25, 0x01,        /*   Logical Maximum (1)              */
+	0x05, 0x08,        /*   Usage Page (LEDs)                */
+	0x09, 0x2A,        /*   Usage (On-Line)                  */
+	0x91, 0x02,        /*   Output (Data,Var,Abs)            */
+	0x09, 0x4B,        /*   Usage (Generic Indicator)        */
+	0x91, 0x02,        /*   Output (Data,Var,Abs)            */
+	0x75, 0x06,        /*   Report Size (6)                  */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x91, 0x01,        /*   Output (Const,Array,Abs)         */
+	0xC0               /* End Collection                     */
+};
+
+/* The patched descriptor, allowing media key events to be accepted as valid */
+static const u8 maltron_rdesc[] = {
+	0x05, 0x01,        /* Usage Page (Generic Desktop Ctrls) */
+	0x09, 0x80,        /* Usage (Sys Control)                */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x02,        /*   Report ID (2)                    */
+	0x75, 0x01,        /*   Report Size (1)                  */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x15, 0x00,        /*   Logical Minimum (0)              */
+	0x25, 0x01,        /*   Logical Maximum (1)              */
+	0x09, 0x82,        /*   Usage (Sys Sleep)                */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x09, 0x82,        /*   Usage (Sys Sleep)                */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x09, 0x83,        /*   Usage (Sys Wake Up)              */
+	0x81, 0x06,        /*   Input (Data,Var,Rel)             */
+	0x75, 0x05,        /*   Report Size (5)                  */
+	0x81, 0x01,        /*   Input (Const,Array,Abs)          */
+	0xC0,              /* End Collection                     */
+	0x05, 0x0C,        /* Usage Page (Consumer)              */
+	0x09, 0x01,        /* Usage (Consumer Control)           */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x03,        /*   Report ID (3)                    */
+	0x15, 0x00,        /*   Logical Minimum (0)              - changed */
+	0x26, 0xFF, 0x7F,  /*   Logical Maximum (32767)          - changed */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x75, 0x10,        /*   Report Size (16)                 */
+	0x19, 0x00,        /*   Usage Minimum (Unassigned)       */
+	0x2A, 0xFF, 0x7F,  /*   Usage Maximum (0x7FFF)           */
+	0x81, 0x00,        /*   Input (Data,Array,Abs)           */
+	0xC0,              /* End Collection                     */
+	0x06, 0x7F, 0xFF,  /* Usage Page (Vendor Defined 0xFF7F) */
+	0x09, 0x01,        /* Usage (0x01)                       */
+	0xA1, 0x01,        /* Collection (Application)           */
+	0x85, 0x04,        /*   Report ID (4)                    */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x75, 0x10,        /*   Report Size (16)                 */
+	0x19, 0x00,        /*   Usage Minimum (0x00)             */
+	0x2A, 0xFF, 0x7F,  /*   Usage Maximum (0x7FFF)           */
+	0x81, 0x00,        /*   Input (Data,Array,Abs)           */
+	0x75, 0x02,        /*   Report Size (2)                  */
+	0x25, 0x02,        /*   Logical Maximum (2)              */
+	0x09, 0x90,        /*   Usage (0x90)                     */
+	0xB1, 0x02,        /*   Feature (Data,Var,Abs)           */
+	0x75, 0x06,        /*   Report Size (6)                  */
+	0xB1, 0x01,        /*   Feature (Const,Array,Abs)        */
+	0x75, 0x01,        /*   Report Size (1)                  */
+	0x25, 0x01,        /*   Logical Maximum (1)              */
+	0x05, 0x08,        /*   Usage Page (LEDs)                */
+	0x09, 0x2A,        /*   Usage (On-Line)                  */
+	0x91, 0x02,        /*   Output (Data,Var,Abs)            */
+	0x09, 0x4B,        /*   Usage (Generic Indicator)        */
+	0x91, 0x02,        /*   Output (Data,Var,Abs)            */
+	0x75, 0x06,        /*   Report Size (6)                  */
+	0x95, 0x01,        /*   Report Count (1)                 */
+	0x91, 0x01,        /*   Output (Const,Array,Abs)         */
+	0xC0               /* End Collection                     */
+};
+
+static const __u8 *maltron_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+					unsigned int *rsize)
+{
+	if (*rsize == sizeof(maltron_rdesc_o) &&
+	    !memcmp(maltron_rdesc_o, rdesc, sizeof(maltron_rdesc_o))) {
+		hid_info(hdev, "Replacing Maltron L90 keyboard report descriptor\n");
+		*rsize = sizeof(maltron_rdesc);
+		return maltron_rdesc;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id maltron_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ALCOR, USB_DEVICE_ID_ALCOR_MALTRON_KB)},
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, maltron_devices);
+
+static struct hid_driver maltron_driver = {
+	.name = "maltron",
+	.id_table = maltron_devices,
+	.report_fixup = maltron_report_fixup
+};
+module_hid_driver(maltron_driver);
+
+MODULE_DESCRIPTION("HID driver for Maltron L90");
+MODULE_LICENSE("GPL");