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, 36 insertions, 0 deletions

diff --git a/drivers/scsi/fcoe/libfcoe.h b/drivers/scsi/fcoe/libfcoe.h
new file mode 100644
index 000000000..b8bdfab51
--- /dev/null
+++ b/drivers/scsi/fcoe/libfcoe.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _FCOE_LIBFCOE_H_
+#define _FCOE_LIBFCOE_H_
+
+extern unsigned int libfcoe_debug_logging;
+#define LIBFCOE_LOGGING	          0x01 /* General logging, not categorized */
+#define LIBFCOE_FIP_LOGGING       0x02 /* FIP logging */
+#define LIBFCOE_TRANSPORT_LOGGING 0x04 /* FCoE transport logging */
+#define LIBFCOE_SYSFS_LOGGING     0x08 /* fcoe_sysfs logging */
+
+#define LIBFCOE_CHECK_LOGGING(LEVEL, CMD)		\
+do {							\
+	if (unlikely(libfcoe_debug_logging & LEVEL))	\
+		do {					\
+			CMD;				\
+		} while (0);				\
+} while (0)
+
+#define LIBFCOE_DBG(fmt, args...)					\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_LOGGING,				\
+			      pr_info("libfcoe: " fmt, ##args);)
+
+#define LIBFCOE_FIP_DBG(fip, fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_FIP_LOGGING,			\
+			      pr_info("host%d: fip: " fmt,		\
+				      (fip)->lp->host->host_no, ##args);)
+
+#define LIBFCOE_TRANSPORT_DBG(fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_TRANSPORT_LOGGING,		\
+			      pr_info("%s: " fmt, __func__, ##args);)
+
+#define LIBFCOE_SYSFS_DBG(cdev, fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_SYSFS_LOGGING,			\
+			      pr_info("ctlr_%d: " fmt, cdev->id, ##args);)
+
+#endif /* _FCOE_LIBFCOE_H_ */