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, 156 insertions, 0 deletions

diff --git a/drivers/hid/hid-lgff.c b/drivers/hid/hid-lgff.c
new file mode 100644
index 000000000..aed4ddc39
--- /dev/null
+++ b/drivers/hid/hid-lgff.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Force feedback support for hid-compliant for some of the devices from
+ * Logitech, namely:
+ * - WingMan Cordless RumblePad
+ * - WingMan Force 3D
+ *
+ *  Copyright (c) 2002-2004 Johann Deneux
+ *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ */
+
+/*
+ *
+ * Should you need to contact me, the author, you can do so by
+ * e-mail - mail your message to <johann.deneux@it.uu.se>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/input.h>
+#include <linux/hid.h>
+
+#include "hid-lg.h"
+
+struct dev_type {
+	u16 idVendor;
+	u16 idProduct;
+	const signed short *ff;
+};
+
+static const signed short ff_rumble[] = {
+	FF_RUMBLE,
+	-1
+};
+
+static const signed short ff_joystick[] = {
+	FF_CONSTANT,
+	-1
+};
+
+static const signed short ff_joystick_ac[] = {
+	FF_CONSTANT,
+	FF_AUTOCENTER,
+	-1
+};
+
+static const struct dev_type devices[] = {
+	{ 0x046d, 0xc211, ff_rumble },
+	{ 0x046d, 0xc219, ff_rumble },
+	{ 0x046d, 0xc283, ff_joystick },
+	{ 0x046d, 0xc286, ff_joystick_ac },
+	{ 0x046d, 0xc287, ff_joystick_ac },
+	{ 0x046d, 0xc293, ff_joystick },
+	{ 0x046d, 0xc295, ff_joystick },
+};
+
+static int hid_lgff_play(struct input_dev *dev, void *data, struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	int x, y;
+	unsigned int left, right;
+
+#define CLAMP(x) if (x < 0) x = 0; if (x > 0xff) x = 0xff
+
+	switch (effect->type) {
+	case FF_CONSTANT:
+		x = effect->u.ramp.start_level + 0x7f;	/* 0x7f is center */
+		y = effect->u.ramp.end_level + 0x7f;
+		CLAMP(x);
+		CLAMP(y);
+		report->field[0]->value[0] = 0x51;
+		report->field[0]->value[1] = 0x08;
+		report->field[0]->value[2] = x;
+		report->field[0]->value[3] = y;
+		dbg_hid("(x, y)=(%04x, %04x)\n", x, y);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+
+	case FF_RUMBLE:
+		right = effect->u.rumble.strong_magnitude;
+		left = effect->u.rumble.weak_magnitude;
+		right = right * 0xff / 0xffff;
+		left = left * 0xff / 0xffff;
+		CLAMP(left);
+		CLAMP(right);
+		report->field[0]->value[0] = 0x42;
+		report->field[0]->value[1] = 0x00;
+		report->field[0]->value[2] = left;
+		report->field[0]->value[3] = right;
+		dbg_hid("(left, right)=(%04x, %04x)\n", left, right);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+	}
+	return 0;
+}
+
+static void hid_lgff_set_autocenter(struct input_dev *dev, u16 magnitude)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	__s32 *value = report->field[0]->value;
+	magnitude = (magnitude >> 12) & 0xf;
+	*value++ = 0xfe;
+	*value++ = 0x0d;
+	*value++ = magnitude;   /* clockwise strength */
+	*value++ = magnitude;   /* counter-clockwise strength */
+	*value++ = 0x80;
+	*value++ = 0x00;
+	*value = 0x00;
+	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+}
+
+int lgff_init(struct hid_device* hid)
+{
+	struct hid_input *hidinput;
+	struct input_dev *dev;
+	const signed short *ff_bits = ff_joystick;
+	int error;
+	int i;
+
+	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 */
+	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7))
+		return -ENODEV;
+
+	for (i = 0; i < ARRAY_SIZE(devices); i++) {
+		if (dev->id.vendor == devices[i].idVendor &&
+		    dev->id.product == devices[i].idProduct) {
+			ff_bits = devices[i].ff;
+			break;
+		}
+	}
+
+	for (i = 0; ff_bits[i] >= 0; i++)
+		set_bit(ff_bits[i], dev->ffbit);
+
+	error = input_ff_create_memless(dev, NULL, hid_lgff_play);
+	if (error)
+		return error;
+
+	if ( test_bit(FF_AUTOCENTER, dev->ffbit) )
+		dev->ff->set_autocenter = hid_lgff_set_autocenter;
+
+	pr_info("Force feedback for Logitech force feedback devices by Johann Deneux <johann.deneux@it.uu.se>\n");
+
+	return 0;
+}