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, 109 insertions, 0 deletions

diff --git a/fs/jfs/jfs_debug.h b/fs/jfs/jfs_debug.h
new file mode 100644
index 000000000..48e2150c0
--- /dev/null
+++ b/fs/jfs/jfs_debug.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) International Business Machines Corp., 2000-2002
+ *   Portions Copyright (C) Christoph Hellwig, 2001-2002
+ */
+#ifndef _H_JFS_DEBUG
+#define _H_JFS_DEBUG
+
+/*
+ *	jfs_debug.h
+ *
+ * global debug message, data structure/macro definitions
+ * under control of CONFIG_JFS_DEBUG, CONFIG_JFS_STATISTICS;
+ */
+
+/*
+ * Create /proc/fs/jfs if procfs is enabled andeither
+ * CONFIG_JFS_DEBUG or CONFIG_JFS_STATISTICS is defined
+ */
+#if defined(CONFIG_PROC_FS) && (defined(CONFIG_JFS_DEBUG) || defined(CONFIG_JFS_STATISTICS))
+#define PROC_FS_JFS
+extern void jfs_proc_init(void);
+extern void jfs_proc_clean(void);
+#endif
+
+/*
+ *	assert with traditional printf/panic
+ */
+#define assert(p) do {	\
+	if (!(p)) {	\
+		printk(KERN_CRIT "BUG at %s:%d assert(%s)\n",	\
+		       __FILE__, __LINE__, #p);			\
+		BUG();	\
+	}		\
+} while (0)
+
+/*
+ *	debug ON
+ *	--------
+ */
+#ifdef CONFIG_JFS_DEBUG
+#define ASSERT(p) assert(p)
+
+/* printk verbosity */
+#define JFS_LOGLEVEL_ERR 1
+#define JFS_LOGLEVEL_WARN 2
+#define JFS_LOGLEVEL_DEBUG 3
+#define JFS_LOGLEVEL_INFO 4
+
+extern int jfsloglevel;
+
+int jfs_txanchor_proc_show(struct seq_file *m, void *v);
+
+/* information message: e.g., configuration, major event */
+#define jfs_info(fmt, arg...) do {			\
+	if (jfsloglevel >= JFS_LOGLEVEL_INFO)		\
+		printk(KERN_INFO fmt "\n", ## arg);	\
+} while (0)
+
+/* debug message: ad hoc */
+#define jfs_debug(fmt, arg...) do {			\
+	if (jfsloglevel >= JFS_LOGLEVEL_DEBUG)		\
+		printk(KERN_DEBUG fmt "\n", ## arg);	\
+} while (0)
+
+/* warn message: */
+#define jfs_warn(fmt, arg...) do {			\
+	if (jfsloglevel >= JFS_LOGLEVEL_WARN)		\
+		printk(KERN_WARNING fmt "\n", ## arg);	\
+} while (0)
+
+/* error event message: e.g., i/o error */
+#define jfs_err(fmt, arg...) do {			\
+	if (jfsloglevel >= JFS_LOGLEVEL_ERR)		\
+		printk(KERN_ERR fmt "\n", ## arg);	\
+} while (0)
+
+/*
+ *	debug OFF
+ *	---------
+ */
+#else				/* CONFIG_JFS_DEBUG */
+#define ASSERT(p) do {} while (0)
+#define jfs_info(fmt, arg...) do {} while (0)
+#define jfs_debug(fmt, arg...) do {} while (0)
+#define jfs_warn(fmt, arg...) do {} while (0)
+#define jfs_err(fmt, arg...) do {} while (0)
+#endif				/* CONFIG_JFS_DEBUG */
+
+/*
+ *	statistics
+ *	----------
+ */
+#ifdef	CONFIG_JFS_STATISTICS
+int jfs_lmstats_proc_show(struct seq_file *m, void *v);
+int jfs_txstats_proc_show(struct seq_file *m, void *v);
+int jfs_mpstat_proc_show(struct seq_file *m, void *v);
+int jfs_xtstat_proc_show(struct seq_file *m, void *v);
+
+#define	INCREMENT(x)		((x)++)
+#define	DECREMENT(x)		((x)--)
+#define	HIGHWATERMARK(x,y)	((x) = max((x), (y)))
+#else
+#define	INCREMENT(x)
+#define	DECREMENT(x)
+#define	HIGHWATERMARK(x,y)
+#endif				/* CONFIG_JFS_STATISTICS */
+
+#endif				/* _H_JFS_DEBUG */