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, 95 insertions, 0 deletions

diff --git a/drivers/hid/hid-lg2ff.c b/drivers/hid/hid-lg2ff.c
new file mode 100644
index 000000000..c3e85b079
--- /dev/null
+++ b/drivers/hid/hid-lg2ff.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Force feedback support for Logitech RumblePad and Rumblepad 2
+ *
+ *  Copyright (c) 2008 Anssi Hannula <anssi.hannula@gmail.com>
+ */
+
+/*
+ */
+
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+
+#include "hid-lg.h"
+
+struct lg2ff_device {
+	struct hid_report *report;
+};
+
+static int play_effect(struct input_dev *dev, void *data,
+			 struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct lg2ff_device *lg2ff = data;
+	int weak, strong;
+
+	strong = effect->u.rumble.strong_magnitude;
+	weak = effect->u.rumble.weak_magnitude;
+
+	if (weak || strong) {
+		weak = weak * 0xff / 0xffff;
+		strong = strong * 0xff / 0xffff;
+
+		lg2ff->report->field[0]->value[0] = 0x51;
+		lg2ff->report->field[0]->value[2] = weak;
+		lg2ff->report->field[0]->value[4] = strong;
+	} else {
+		lg2ff->report->field[0]->value[0] = 0xf3;
+		lg2ff->report->field[0]->value[2] = 0x00;
+		lg2ff->report->field[0]->value[4] = 0x00;
+	}
+
+	hid_hw_request(hid, lg2ff->report, HID_REQ_SET_REPORT);
+	return 0;
+}
+
+int lg2ff_init(struct hid_device *hid)
+{
+	struct lg2ff_device *lg2ff;
+	struct hid_report *report;
+	struct hid_input *hidinput;
+	struct input_dev *dev;
+	int error;
+
+	if (list_empty(&hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
+	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
+	dev = hidinput->input;
+
+	/* Check that the report looks ok */
+	report = hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7);
+	if (!report)
+		return -ENODEV;
+
+	lg2ff = kmalloc_obj(struct lg2ff_device);
+	if (!lg2ff)
+		return -ENOMEM;
+
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, lg2ff, play_effect);
+	if (error) {
+		kfree(lg2ff);
+		return error;
+	}
+
+	lg2ff->report = report;
+	report->field[0]->value[0] = 0xf3;
+	report->field[0]->value[1] = 0x00;
+	report->field[0]->value[2] = 0x00;
+	report->field[0]->value[3] = 0x00;
+	report->field[0]->value[4] = 0x00;
+	report->field[0]->value[5] = 0x00;
+	report->field[0]->value[6] = 0x00;
+
+	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+
+	hid_info(hid, "Force feedback for Logitech variant 2 rumble devices by Anssi Hannula <anssi.hannula@gmail.com>\n");
+
+	return 0;
+}