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, 255 insertions, 0 deletions

diff --git a/drivers/media/rc/ir-rcmm-decoder.c b/drivers/media/rc/ir-rcmm-decoder.c
new file mode 100644
index 000000000..a8a34436f
--- /dev/null
+++ b/drivers/media/rc/ir-rcmm-decoder.c
@@ -0,0 +1,255 @@
+// SPDX-License-Identifier: GPL-2.0+
+// ir-rcmm-decoder.c - A decoder for the RCMM IR protocol
+//
+// Copyright (C) 2018 by Patrick Lerda <patrick9876@free.fr>
+
+#include "rc-core-priv.h"
+#include <linux/module.h>
+
+#define RCMM_UNIT		166  /* microseconds */
+#define RCMM_PREFIX_PULSE	417  /* 166.666666666666*2.5 */
+#define RCMM_PULSE_0            278  /* 166.666666666666*(1+2/3) */
+#define RCMM_PULSE_1            444  /* 166.666666666666*(2+2/3) */
+#define RCMM_PULSE_2            611  /* 166.666666666666*(3+2/3) */
+#define RCMM_PULSE_3            778  /* 166.666666666666*(4+2/3) */
+
+enum rcmm_state {
+	STATE_INACTIVE,
+	STATE_LOW,
+	STATE_BUMP,
+	STATE_VALUE,
+	STATE_FINISHED,
+};
+
+static bool rcmm_mode(const struct rcmm_dec *data)
+{
+	return !((0x000c0000 & data->bits) == 0x000c0000);
+}
+
+static int rcmm_miscmode(struct rc_dev *dev, struct rcmm_dec *data)
+{
+	switch (data->count) {
+	case 24:
+		if (dev->enabled_protocols & RC_PROTO_BIT_RCMM24) {
+			rc_keydown(dev, RC_PROTO_RCMM24, data->bits, 0);
+			data->state = STATE_INACTIVE;
+			return 0;
+		}
+		return -1;
+
+	case 12:
+		if (dev->enabled_protocols & RC_PROTO_BIT_RCMM12) {
+			rc_keydown(dev, RC_PROTO_RCMM12, data->bits, 0);
+			data->state = STATE_INACTIVE;
+			return 0;
+		}
+		return -1;
+	}
+
+	return -1;
+}
+
+/**
+ * ir_rcmm_decode() - Decode one RCMM pulse or space
+ * @dev:	the struct rc_dev descriptor of the device
+ * @ev:		the struct ir_raw_event descriptor of the pulse/space
+ *
+ * This function returns -EINVAL if the pulse violates the state machine
+ */
+static int ir_rcmm_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct rcmm_dec *data = &dev->raw->rcmm;
+	u32 scancode;
+	u8 toggle;
+	int value;
+
+	if (!(dev->enabled_protocols & (RC_PROTO_BIT_RCMM32 |
+					RC_PROTO_BIT_RCMM24 |
+					RC_PROTO_BIT_RCMM12)))
+		return 0;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	switch (data->state) {
+	case STATE_INACTIVE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, RCMM_PREFIX_PULSE, RCMM_UNIT))
+			break;
+
+		data->state = STATE_LOW;
+		data->count = 0;
+		data->bits  = 0;
+		return 0;
+
+	case STATE_LOW:
+		if (ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, RCMM_PULSE_0, RCMM_UNIT))
+			break;
+
+		data->state = STATE_BUMP;
+		return 0;
+
+	case STATE_BUMP:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, RCMM_UNIT, RCMM_UNIT / 2))
+			break;
+
+		data->state = STATE_VALUE;
+		return 0;
+
+	case STATE_VALUE:
+		if (ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, RCMM_PULSE_0, RCMM_UNIT / 2))
+			value = 0;
+		else if (eq_margin(ev.duration, RCMM_PULSE_1, RCMM_UNIT / 2))
+			value = 1;
+		else if (eq_margin(ev.duration, RCMM_PULSE_2, RCMM_UNIT / 2))
+			value = 2;
+		else if (eq_margin(ev.duration, RCMM_PULSE_3, RCMM_UNIT / 2))
+			value = 3;
+		else
+			value = -1;
+
+		if (value == -1) {
+			if (!rcmm_miscmode(dev, data))
+				return 0;
+			break;
+		}
+
+		data->bits <<= 2;
+		data->bits |= value;
+
+		data->count += 2;
+
+		if (data->count < 32)
+			data->state = STATE_BUMP;
+		else
+			data->state = STATE_FINISHED;
+
+		return 0;
+
+	case STATE_FINISHED:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, RCMM_UNIT, RCMM_UNIT / 2))
+			break;
+
+		if (rcmm_mode(data)) {
+			toggle = !!(0x8000 & data->bits);
+			scancode = data->bits & ~0x8000;
+		} else {
+			toggle = 0;
+			scancode = data->bits;
+		}
+
+		if (dev->enabled_protocols & RC_PROTO_BIT_RCMM32) {
+			rc_keydown(dev, RC_PROTO_RCMM32, scancode, toggle);
+			data->state = STATE_INACTIVE;
+			return 0;
+		}
+
+		break;
+	}
+
+	dev_dbg(&dev->dev, "RC-MM decode failed at count %d state %d (%uus %s)\n",
+		data->count, data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static const int rcmmspace[] = {
+	RCMM_PULSE_0,
+	RCMM_PULSE_1,
+	RCMM_PULSE_2,
+	RCMM_PULSE_3,
+};
+
+static int ir_rcmm_rawencoder(struct ir_raw_event **ev, unsigned int max,
+			      unsigned int n, u32 data)
+{
+	int i;
+	int ret;
+
+	ret = ir_raw_gen_pulse_space(ev, &max, RCMM_PREFIX_PULSE, RCMM_PULSE_0);
+	if (ret)
+		return ret;
+
+	for (i = n - 2; i >= 0; i -= 2) {
+		const unsigned int space = rcmmspace[(data >> i) & 3];
+
+		ret = ir_raw_gen_pulse_space(ev, &max, RCMM_UNIT, space);
+		if (ret)
+			return ret;
+	}
+
+	return ir_raw_gen_pulse_space(ev, &max, RCMM_UNIT, RCMM_PULSE_3 * 2);
+}
+
+static int ir_rcmm_encode(enum rc_proto protocol, u32 scancode,
+			  struct ir_raw_event *events, unsigned int max)
+{
+	struct ir_raw_event *e = events;
+	int ret;
+
+	switch (protocol) {
+	case RC_PROTO_RCMM32:
+		ret = ir_rcmm_rawencoder(&e, max, 32, scancode);
+		break;
+	case RC_PROTO_RCMM24:
+		ret = ir_rcmm_rawencoder(&e, max, 24, scancode);
+		break;
+	case RC_PROTO_RCMM12:
+		ret = ir_rcmm_rawencoder(&e, max, 12, scancode);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret < 0)
+		return ret;
+
+	return e - events;
+}
+
+static struct ir_raw_handler rcmm_handler = {
+	.protocols	= RC_PROTO_BIT_RCMM32 |
+			  RC_PROTO_BIT_RCMM24 |
+			  RC_PROTO_BIT_RCMM12,
+	.decode		= ir_rcmm_decode,
+	.encode         = ir_rcmm_encode,
+	.carrier        = 36000,
+	.min_timeout	= RCMM_PULSE_3 + RCMM_UNIT,
+};
+
+static int __init ir_rcmm_decode_init(void)
+{
+	ir_raw_handler_register(&rcmm_handler);
+
+	pr_info("IR RCMM protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_rcmm_decode_exit(void)
+{
+	ir_raw_handler_unregister(&rcmm_handler);
+}
+
+module_init(ir_rcmm_decode_init);
+module_exit(ir_rcmm_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick Lerda");
+MODULE_DESCRIPTION("RCMM IR protocol decoder");