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, 60 insertions, 0 deletions

diff --git a/drivers/hid/hid-xinmo.c b/drivers/hid/hid-xinmo.c
new file mode 100644
index 000000000..66b8bfb6e
--- /dev/null
+++ b/drivers/hid/hid-xinmo.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Xin-Mo devices, currently only the Dual Arcade controller.
+ *  Fixes the negative axis event values (the devices sends -2) to match the
+ *  logical axis minimum of the HID report descriptor (the report announces
+ *  -1). It is needed because hid-input discards out of bounds values.
+ *  (This module is based on "hid-saitek" and "hid-lg".)
+ *
+ *  Copyright (c) 2013 Olivier Scherler
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include "hid-ids.h"
+
+/*
+ * Fix negative events that are out of bounds.
+ */
+static int xinmo_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	switch (usage->code) {
+	case ABS_X:
+	case ABS_Y:
+	case ABS_Z:
+	case ABS_RX:
+		if (value < -1) {
+			input_event(field->hidinput->input, usage->type,
+				usage->code, -1);
+			return 1;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id xinmo_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_XIN_MO, USB_DEVICE_ID_XIN_MO_DUAL_ARCADE) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_XIN_MO, USB_DEVICE_ID_THT_2P_ARCADE) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, xinmo_devices);
+
+static struct hid_driver xinmo_driver = {
+	.name = "xinmo",
+	.id_table = xinmo_devices,
+	.event = xinmo_event
+};
+
+module_hid_driver(xinmo_driver);
+MODULE_DESCRIPTION("HID driver for Xin-Mo devices");
+MODULE_LICENSE("GPL");