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, 192 insertions, 0 deletions

diff --git a/drivers/hid/hid-cypress.c b/drivers/hid/hid-cypress.c
new file mode 100644
index 000000000..f18fddc17
--- /dev/null
+++ b/drivers/hid/hid-cypress.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some cypress "special" devices
+ *
+ *  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) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/input.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define CP_RDESC_SWAPPED_MIN_MAX	0x01
+#define CP_2WHEEL_MOUSE_HACK		0x02
+#define CP_2WHEEL_MOUSE_HACK_ON		0x04
+
+#define VA_INVAL_LOGICAL_BOUNDARY	0x08
+
+struct cp_device {
+	unsigned long quirks;
+};
+
+/*
+ * Some USB barcode readers from cypress have usage min and usage max in
+ * the wrong order
+ */
+static __u8 *cp_rdesc_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	unsigned int i;
+
+	if (*rsize < 4)
+		return rdesc;
+
+	for (i = 0; i < *rsize - 4; i++)
+		if (rdesc[i] == 0x29 && rdesc[i + 2] == 0x19) {
+			rdesc[i] = 0x19;
+			rdesc[i + 2] = 0x29;
+			swap(rdesc[i + 3], rdesc[i + 1]);
+		}
+	return rdesc;
+}
+
+static __u8 *va_logical_boundary_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	/*
+	 * Varmilo VA104M (with VID Cypress and device ID 07B1) incorrectly
+	 * reports Logical Minimum of its Consumer Control device as 572
+	 * (0x02 0x3c). Fix this by setting its Logical Minimum to zero.
+	 */
+	if (*rsize == 25 &&
+			rdesc[0] == 0x05 && rdesc[1] == 0x0c &&
+			rdesc[2] == 0x09 && rdesc[3] == 0x01 &&
+			rdesc[6] == 0x19 && rdesc[7] == 0x00 &&
+			rdesc[11] == 0x16 && rdesc[12] == 0x3c && rdesc[13] == 0x02) {
+		hid_info(hdev,
+			 "fixing up varmilo VA104M consumer control report descriptor\n");
+		rdesc[12] = 0x00;
+		rdesc[13] = 0x00;
+	}
+	return rdesc;
+}
+
+static const __u8 *cp_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	const struct cp_device *cp_device = hid_get_drvdata(hdev);
+	unsigned long quirks = cp_device->quirks;
+
+	if (quirks & CP_RDESC_SWAPPED_MIN_MAX)
+		rdesc = cp_rdesc_fixup(hdev, rdesc, rsize);
+	if (quirks & VA_INVAL_LOGICAL_BOUNDARY)
+		rdesc = va_logical_boundary_fixup(hdev, rdesc, rsize);
+
+	return rdesc;
+}
+
+static int cp_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	const struct cp_device *cp_device = hid_get_drvdata(hdev);
+	unsigned long quirks = cp_device->quirks;
+
+	if (!(quirks & CP_2WHEEL_MOUSE_HACK))
+		return 0;
+
+	if (usage->type == EV_REL && usage->code == REL_WHEEL)
+		set_bit(REL_HWHEEL, *bit);
+	if (usage->hid == 0x00090005)
+		return -1;
+
+	return 0;
+}
+
+static int cp_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	struct cp_device *cp_device = hid_get_drvdata(hdev);
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type || !(cp_device->quirks & CP_2WHEEL_MOUSE_HACK))
+		return 0;
+
+	if (usage->hid == 0x00090005) {
+		if (value)
+			cp_device->quirks |= CP_2WHEEL_MOUSE_HACK_ON;
+		else
+			cp_device->quirks &= ~CP_2WHEEL_MOUSE_HACK_ON;
+		return 1;
+	}
+
+	if (usage->code == REL_WHEEL && (cp_device->quirks & CP_2WHEEL_MOUSE_HACK_ON)) {
+		struct input_dev *input = field->hidinput->input;
+
+		input_event(input, usage->type, REL_HWHEEL, value);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int cp_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct cp_device *cp_device;
+
+	cp_device = devm_kzalloc(&hdev->dev, sizeof(*cp_device), GFP_KERNEL);
+
+	if (!cp_device)
+		return -ENOMEM;
+
+	cp_device->quirks = id->driver_data;
+
+	hid_set_drvdata(hdev, cp_device);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		goto err_free;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		goto err_free;
+	}
+
+	return 0;
+err_free:
+	return ret;
+}
+
+static const struct hid_device_id cp_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_1),
+		.driver_data = CP_RDESC_SWAPPED_MIN_MAX },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_2),
+		.driver_data = CP_RDESC_SWAPPED_MIN_MAX },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_3),
+		.driver_data = CP_RDESC_SWAPPED_MIN_MAX },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_4),
+		.driver_data = CP_RDESC_SWAPPED_MIN_MAX },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_MOUSE),
+		.driver_data = CP_2WHEEL_MOUSE_HACK },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_VARMILO_VA104M_07B1),
+		.driver_data = VA_INVAL_LOGICAL_BOUNDARY },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, cp_devices);
+
+static struct hid_driver cp_driver = {
+	.name = "cypress",
+	.id_table = cp_devices,
+	.report_fixup = cp_report_fixup,
+	.input_mapped = cp_input_mapped,
+	.event = cp_event,
+	.probe = cp_probe,
+};
+module_hid_driver(cp_driver);
+
+MODULE_DESCRIPTION("HID driver for some cypress \"special\" devices");
+MODULE_LICENSE("GPL");