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, 114 insertions, 0 deletions

diff --git a/drivers/hid/hid-holtek-mouse.c b/drivers/hid/hid-holtek-mouse.c
new file mode 100644
index 000000000..b618a1646
--- /dev/null
+++ b/drivers/hid/hid-holtek-mouse.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HID driver for Holtek gaming mice
+ * Copyright (c) 2013 Christian Ohm
+ * Heavily inspired by various other HID drivers that adjust the report
+ * descriptor.
+*/
+
+/*
+ */
+
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+/*
+ * The report descriptor of some Holtek based gaming mice specifies an
+ * excessively large number of consumer usages (2^15), which is more than
+ * HID_MAX_USAGES. This prevents proper parsing of the report descriptor.
+ *
+ * This driver fixes the report descriptor for:
+ * - USB ID 04d9:a067, sold as Sharkoon Drakonia and Perixx MX-2000
+ * - USB ID 04d9:a04a, sold as Tracer Sniper TRM-503, NOVA Gaming Slider X200
+ *   and Zalman ZM-GM1
+ * - USB ID 04d9:a081, sold as SHARKOON DarkGlider Gaming mouse
+ * - USB ID 04d9:a072, sold as LEETGION Hellion Gaming Mouse
+ * - USB ID 04d9:a0c2, sold as ETEKCITY Scroll T-140 Gaming Mouse
+ */
+
+static const __u8 *holtek_mouse_report_fixup(struct hid_device *hdev,
+		__u8 *rdesc, unsigned int *rsize)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		/* Change usage maximum and logical maximum from 0x7fff to
+		 * 0x2fff, so they don't exceed HID_MAX_USAGES */
+		switch (hdev->product) {
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A067:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A072:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A0C2:
+			if (*rsize >= 122 && rdesc[115] == 0xff && rdesc[116] == 0x7f
+					&& rdesc[120] == 0xff && rdesc[121] == 0x7f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[116] = rdesc[121] = 0x2f;
+			}
+			break;
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A04A:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A070:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A081:
+			if (*rsize >= 113 && rdesc[106] == 0xff && rdesc[107] == 0x7f
+					&& rdesc[111] == 0xff && rdesc[112] == 0x7f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[107] = rdesc[112] = 0x2f;
+			}
+			break;
+		}
+
+	}
+	return rdesc;
+}
+
+static int holtek_mouse_probe(struct hid_device *hdev,
+			      const struct hid_device_id *id)
+{
+	int ret;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "hid parse failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id holtek_mouse_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A067) },
+        { HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A070) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A04A) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A072) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A081) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A0C2) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, holtek_mouse_devices);
+
+static struct hid_driver holtek_mouse_driver = {
+	.name = "holtek_mouse",
+	.id_table = holtek_mouse_devices,
+	.report_fixup = holtek_mouse_report_fixup,
+	.probe = holtek_mouse_probe,
+};
+
+module_hid_driver(holtek_mouse_driver);
+MODULE_DESCRIPTION("HID driver for Holtek gaming mice");
+MODULE_LICENSE("GPL");