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>

4 files changed, 253 insertions, 0 deletions

diff --git a/tools/testing/selftests/ir/.gitignore b/tools/testing/selftests/ir/.gitignore
new file mode 100644
index 000000000..0bbada8c1
--- /dev/null
+++ b/tools/testing/selftests/ir/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+ir_loopback
diff --git a/tools/testing/selftests/ir/Makefile b/tools/testing/selftests/ir/Makefile
new file mode 100644
index 000000000..ad06489c2
--- /dev/null
+++ b/tools/testing/selftests/ir/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_PROGS := ir_loopback.sh
+TEST_GEN_PROGS_EXTENDED := ir_loopback
+APIDIR := ../../../include/uapi
+CFLAGS += -Wall -O2 -I$(APIDIR)
+
+include ../lib.mk
diff --git a/tools/testing/selftests/ir/ir_loopback.c b/tools/testing/selftests/ir/ir_loopback.c
new file mode 100644
index 000000000..adfcf50b1
--- /dev/null
+++ b/tools/testing/selftests/ir/ir_loopback.c
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0
+// test ir decoder
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+// When sending LIRC_MODE_SCANCODE, the IR will be encoded. rc-loopback
+// will send this IR to the receiver side, where we try to read the decoded
+// IR. Decoding happens in a separate kernel thread, so we will need to
+// wait until that is scheduled, hence we use poll to check for read
+// readiness.
+
+#include <linux/lirc.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <poll.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "kselftest.h"
+
+#define TEST_SCANCODES	10
+#define SYSFS_PATH_MAX 256
+#define DNAME_PATH_MAX 256
+
+/*
+ * Support ancient lirc.h which does not have these values. Can be removed
+ * once RHEL 8 is no longer a relevant testing platform.
+ */
+#if RC_PROTO_MAX < 26
+#define RC_PROTO_RCMM12 24
+#define RC_PROTO_RCMM24 25
+#define RC_PROTO_RCMM32 26
+#endif
+
+static const struct {
+	enum rc_proto proto;
+	const char *name;
+	unsigned int mask;
+	const char *decoder;
+} protocols[] = {
+	{ RC_PROTO_RC5, "rc-5", 0x1f7f, "rc-5" },
+	{ RC_PROTO_RC5X_20, "rc-5x-20", 0x1f7f3f, "rc-5" },
+	{ RC_PROTO_RC5_SZ, "rc-5-sz", 0x2fff, "rc-5-sz" },
+	{ RC_PROTO_JVC, "jvc", 0xffff, "jvc" },
+	{ RC_PROTO_SONY12, "sony-12", 0x1f007f, "sony" },
+	{ RC_PROTO_SONY15, "sony-15", 0xff007f, "sony" },
+	{ RC_PROTO_SONY20, "sony-20", 0x1fff7f, "sony" },
+	{ RC_PROTO_NEC, "nec", 0xffff, "nec" },
+	{ RC_PROTO_NECX, "nec-x", 0xffffff, "nec" },
+	{ RC_PROTO_NEC32, "nec-32", 0xffffffff, "nec" },
+	{ RC_PROTO_SANYO, "sanyo", 0x1fffff, "sanyo" },
+	{ RC_PROTO_RC6_0, "rc-6-0", 0xffff, "rc-6" },
+	{ RC_PROTO_RC6_6A_20, "rc-6-6a-20", 0xfffff, "rc-6" },
+	{ RC_PROTO_RC6_6A_24, "rc-6-6a-24", 0xffffff, "rc-6" },
+	{ RC_PROTO_RC6_6A_32, "rc-6-6a-32", 0xffffffff, "rc-6" },
+	{ RC_PROTO_RC6_MCE, "rc-6-mce", 0x00007fff, "rc-6" },
+	{ RC_PROTO_SHARP, "sharp", 0x1fff, "sharp" },
+	{ RC_PROTO_IMON, "imon", 0x7fffffff, "imon" },
+	{ RC_PROTO_RCMM12, "rcmm-12", 0x00000fff, "rc-mm" },
+	{ RC_PROTO_RCMM24, "rcmm-24", 0x00ffffff, "rc-mm" },
+	{ RC_PROTO_RCMM32, "rcmm-32", 0xffffffff, "rc-mm" },
+};
+
+int lirc_open(const char *rc)
+{
+	struct dirent *dent;
+	char buf[SYSFS_PATH_MAX + DNAME_PATH_MAX];
+	DIR *d;
+	int fd;
+
+	snprintf(buf, sizeof(buf), "/sys/class/rc/%s", rc);
+
+	d = opendir(buf);
+	if (!d)
+		ksft_exit_fail_msg("cannot open %s: %m\n", buf);
+
+	while ((dent = readdir(d)) != NULL) {
+		if (!strncmp(dent->d_name, "lirc", 4)) {
+			snprintf(buf, sizeof(buf), "/dev/%s", dent->d_name);
+			break;
+		}
+	}
+
+	if (!dent)
+		ksft_exit_skip("cannot find lirc device for %s\n", rc);
+
+	closedir(d);
+
+	fd = open(buf, O_RDWR | O_NONBLOCK);
+	if (fd == -1)
+		ksft_exit_fail_msg("cannot open: %s: %m\n", buf);
+
+	return fd;
+}
+
+int main(int argc, char **argv)
+{
+	unsigned int mode;
+	char buf[100];
+	int rlircfd, wlircfd, protocolfd, i, n;
+
+	srand(time(NULL));
+
+	if (argc != 3)
+		ksft_exit_fail_msg("Usage: %s <write rcN> <read rcN>\n",
+				   argv[0]);
+
+	rlircfd = lirc_open(argv[2]);
+	mode = LIRC_MODE_SCANCODE;
+	if (ioctl(rlircfd, LIRC_SET_REC_MODE, &mode))
+		ksft_exit_fail_msg("failed to set scancode rec mode %s: %m\n",
+				   argv[2]);
+
+	wlircfd = lirc_open(argv[1]);
+	if (ioctl(wlircfd, LIRC_SET_SEND_MODE, &mode))
+		ksft_exit_fail_msg("failed to set scancode send mode %s: %m\n",
+				   argv[1]);
+
+	snprintf(buf, sizeof(buf), "/sys/class/rc/%s/protocols", argv[2]);
+	protocolfd = open(buf, O_WRONLY);
+	if (protocolfd == -1)
+		ksft_exit_fail_msg("failed to open %s: %m\n", buf);
+
+	printf("Sending IR on %s and receiving IR on %s.\n", argv[1], argv[2]);
+
+	for (i = 0; i < ARRAY_SIZE(protocols); i++) {
+		if (write(protocolfd, protocols[i].decoder,
+			  strlen(protocols[i].decoder)) == -1)
+			ksft_exit_fail_msg("failed to set write decoder\n");
+
+		printf("Testing protocol %s for decoder %s (%d/%d)...\n",
+		       protocols[i].name, protocols[i].decoder,
+		       i + 1, (int)ARRAY_SIZE(protocols));
+
+		for (n = 0; n < TEST_SCANCODES; n++) {
+			unsigned int scancode = rand() & protocols[i].mask;
+			unsigned int rc_proto = protocols[i].proto;
+
+			if (rc_proto == RC_PROTO_RC6_MCE)
+				scancode |= 0x800f0000;
+
+			if (rc_proto == RC_PROTO_NECX &&
+			    (((scancode >> 16) ^ ~(scancode >> 8)) & 0xff) == 0)
+				continue;
+
+			if (rc_proto == RC_PROTO_NEC32 &&
+			    (((scancode >> 8) ^ ~scancode) & 0xff) == 0)
+				continue;
+
+			if (rc_proto == RC_PROTO_RCMM32 &&
+			    (scancode & 0x000c0000) != 0x000c0000 &&
+			    scancode & 0x00008000)
+				continue;
+
+			struct lirc_scancode lsc = {
+				.rc_proto = rc_proto,
+				.scancode = scancode
+			};
+
+			printf("Testing scancode:%x\n", scancode);
+
+			while (write(wlircfd, &lsc, sizeof(lsc)) < 0) {
+				if (errno == EINTR)
+					continue;
+
+				ksft_exit_fail_msg("failed to send ir: %m\n");
+			}
+
+			struct pollfd pfd = { .fd = rlircfd, .events = POLLIN };
+			struct lirc_scancode lsc2;
+
+			poll(&pfd, 1, 1000);
+
+			bool decoded = true;
+
+			while (read(rlircfd, &lsc2, sizeof(lsc2)) < 0) {
+				if (errno == EINTR)
+					continue;
+
+				ksft_test_result_error("no scancode decoded: %m\n");
+				decoded = false;
+				break;
+			}
+
+			if (!decoded)
+				continue;
+
+			if (lsc.rc_proto != lsc2.rc_proto)
+				ksft_test_result_error("decoded protocol is different: %d\n",
+						       lsc2.rc_proto);
+
+			else if (lsc.scancode != lsc2.scancode)
+				ksft_test_result_error("decoded scancode is different: %llx\n",
+						       lsc2.scancode);
+			else
+				ksft_inc_pass_cnt();
+		}
+
+		printf("OK\n");
+	}
+
+	close(rlircfd);
+	close(wlircfd);
+	close(protocolfd);
+
+	if (ksft_get_fail_cnt() > 0)
+		ksft_exit_fail();
+	else
+		ksft_exit_pass();
+
+	return 0;
+}
diff --git a/tools/testing/selftests/ir/ir_loopback.sh b/tools/testing/selftests/ir/ir_loopback.sh
new file mode 100755
index 000000000..aff9299c9
--- /dev/null
+++ b/tools/testing/selftests/ir/ir_loopback.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+if [ $UID != 0 ]; then
+	echo "Please run ir_loopback test as root [SKIP]"
+	exit $ksft_skip
+fi
+
+if ! /sbin/modprobe -q -n rc-loopback; then
+        echo "ir_loopback: module rc-loopback is not found in /lib/modules/`uname -r` [SKIP]"
+        exit $ksft_skip
+fi
+
+/sbin/modprobe rc-loopback
+if [ $? -ne 0 ]; then
+	exit
+fi
+
+RCDEV=$(grep -l DRV_NAME=rc-loopback /sys/class/rc/rc*/uevent | grep -o 'rc[0-9]\+')
+
+./ir_loopback $RCDEV $RCDEV
+exit