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, 235 insertions, 0 deletions

diff --git a/drivers/media/rc/ir-sanyo-decoder.c b/drivers/media/rc/ir-sanyo-decoder.c
new file mode 100644
index 000000000..2bc98c342
--- /dev/null
+++ b/drivers/media/rc/ir-sanyo-decoder.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0
+// ir-sanyo-decoder.c - handle SANYO IR Pulse/Space protocol
+//
+// Copyright (C) 2011 by Mauro Carvalho Chehab
+//
+// This protocol uses the NEC protocol timings. However, data is formatted as:
+//	13 bits Custom Code
+//	13 bits NOT(Custom Code)
+//	8 bits Key data
+//	8 bits NOT(Key data)
+//
+// According with LIRC, this protocol is used on Sanyo, Aiwa and Chinon
+// Information for this protocol is available at the Sanyo LC7461 datasheet.
+
+#include <linux/module.h>
+#include <linux/bitrev.h>
+#include "rc-core-priv.h"
+
+#define SANYO_NBITS		(13+13+8+8)
+#define SANYO_UNIT		563  /* us */
+#define SANYO_HEADER_PULSE	(16  * SANYO_UNIT)
+#define SANYO_HEADER_SPACE	(8   * SANYO_UNIT)
+#define SANYO_BIT_PULSE		(1   * SANYO_UNIT)
+#define SANYO_BIT_0_SPACE	(1   * SANYO_UNIT)
+#define SANYO_BIT_1_SPACE	(3   * SANYO_UNIT)
+#define SANYO_REPEAT_SPACE	(150 * SANYO_UNIT)
+#define	SANYO_TRAILER_PULSE	(1   * SANYO_UNIT)
+#define	SANYO_TRAILER_SPACE	(10  * SANYO_UNIT)	/* in fact, 42 */
+
+enum sanyo_state {
+	STATE_INACTIVE,
+	STATE_HEADER_SPACE,
+	STATE_BIT_PULSE,
+	STATE_BIT_SPACE,
+	STATE_TRAILER_PULSE,
+	STATE_TRAILER_SPACE,
+};
+
+/**
+ * ir_sanyo_decode() - Decode one SANYO 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_sanyo_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct sanyo_dec *data = &dev->raw->sanyo;
+	u32 scancode;
+	u16 address;
+	u8 command, not_command;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow) {
+			dev_dbg(&dev->dev, "SANYO event overflow received. reset to state 0\n");
+			data->state = STATE_INACTIVE;
+		}
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "SANYO decode started at state %d (%uus %s)\n",
+		data->state, ev.duration, TO_STR(ev.pulse));
+
+	switch (data->state) {
+
+	case STATE_INACTIVE:
+		if (!ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, SANYO_HEADER_PULSE, SANYO_UNIT / 2)) {
+			data->count = 0;
+			data->state = STATE_HEADER_SPACE;
+			return 0;
+		}
+		break;
+
+
+	case STATE_HEADER_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, SANYO_HEADER_SPACE, SANYO_UNIT / 2)) {
+			data->state = STATE_BIT_PULSE;
+			return 0;
+		}
+
+		break;
+
+	case STATE_BIT_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, SANYO_BIT_PULSE, SANYO_UNIT / 2))
+			break;
+
+		data->state = STATE_BIT_SPACE;
+		return 0;
+
+	case STATE_BIT_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!data->count && geq_margin(ev.duration, SANYO_REPEAT_SPACE, SANYO_UNIT / 2)) {
+			rc_repeat(dev);
+			dev_dbg(&dev->dev, "SANYO repeat last key\n");
+			data->state = STATE_INACTIVE;
+			return 0;
+		}
+
+		data->bits <<= 1;
+		if (eq_margin(ev.duration, SANYO_BIT_1_SPACE, SANYO_UNIT / 2))
+			data->bits |= 1;
+		else if (!eq_margin(ev.duration, SANYO_BIT_0_SPACE, SANYO_UNIT / 2))
+			break;
+		data->count++;
+
+		if (data->count == SANYO_NBITS)
+			data->state = STATE_TRAILER_PULSE;
+		else
+			data->state = STATE_BIT_PULSE;
+
+		return 0;
+
+	case STATE_TRAILER_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, SANYO_TRAILER_PULSE, SANYO_UNIT / 2))
+			break;
+
+		data->state = STATE_TRAILER_SPACE;
+		return 0;
+
+	case STATE_TRAILER_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!geq_margin(ev.duration, SANYO_TRAILER_SPACE, SANYO_UNIT / 2))
+			break;
+
+		address     = bitrev16((data->bits >> 29) & 0x1fff) >> 3;
+		/* not_address = bitrev16((data->bits >> 16) & 0x1fff) >> 3; */
+		command	    = bitrev8((data->bits >>  8) & 0xff);
+		not_command = bitrev8((data->bits >>  0) & 0xff);
+
+		if ((command ^ not_command) != 0xff) {
+			dev_dbg(&dev->dev, "SANYO checksum error: received 0x%08llx\n",
+				data->bits);
+			data->state = STATE_INACTIVE;
+			return 0;
+		}
+
+		scancode = address << 8 | command;
+		dev_dbg(&dev->dev, "SANYO scancode: 0x%06x\n", scancode);
+		rc_keydown(dev, RC_PROTO_SANYO, scancode, 0);
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "SANYO 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 struct ir_raw_timings_pd ir_sanyo_timings = {
+	.header_pulse  = SANYO_HEADER_PULSE,
+	.header_space  = SANYO_HEADER_SPACE,
+	.bit_pulse     = SANYO_BIT_PULSE,
+	.bit_space[0]  = SANYO_BIT_0_SPACE,
+	.bit_space[1]  = SANYO_BIT_1_SPACE,
+	.trailer_pulse = SANYO_TRAILER_PULSE,
+	.trailer_space = SANYO_TRAILER_SPACE,
+	.msb_first     = 1,
+};
+
+/**
+ * ir_sanyo_encode() - Encode a scancode as a stream of raw events
+ *
+ * @protocol:	protocol to encode
+ * @scancode:	scancode to encode
+ * @events:	array of raw ir events to write into
+ * @max:	maximum size of @events
+ *
+ * Returns:	The number of events written.
+ *		-ENOBUFS if there isn't enough space in the array to fit the
+ *		encoding. In this case all @max events will have been written.
+ */
+static int ir_sanyo_encode(enum rc_proto protocol, u32 scancode,
+			   struct ir_raw_event *events, unsigned int max)
+{
+	struct ir_raw_event *e = events;
+	int ret;
+	u64 raw;
+
+	raw = ((u64)(bitrev16(scancode >> 8) & 0xfff8) << (8 + 8 + 13 - 3)) |
+	      ((u64)(bitrev16(~scancode >> 8) & 0xfff8) << (8 + 8 +  0 - 3)) |
+	      ((bitrev8(scancode) & 0xff) << 8) |
+	      (bitrev8(~scancode) & 0xff);
+
+	ret = ir_raw_gen_pd(&e, max, &ir_sanyo_timings, SANYO_NBITS, raw);
+	if (ret < 0)
+		return ret;
+
+	return e - events;
+}
+
+static struct ir_raw_handler sanyo_handler = {
+	.protocols	= RC_PROTO_BIT_SANYO,
+	.decode		= ir_sanyo_decode,
+	.encode		= ir_sanyo_encode,
+	.carrier	= 38000,
+	.min_timeout	= SANYO_TRAILER_SPACE,
+};
+
+static int __init ir_sanyo_decode_init(void)
+{
+	ir_raw_handler_register(&sanyo_handler);
+
+	printk(KERN_INFO "IR SANYO protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_sanyo_decode_exit(void)
+{
+	ir_raw_handler_unregister(&sanyo_handler);
+}
+
+module_init(ir_sanyo_decode_init);
+module_exit(ir_sanyo_decode_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Mauro Carvalho Chehab");
+MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
+MODULE_DESCRIPTION("SANYO IR protocol decoder");