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, 170 insertions, 0 deletions

diff --git a/net/sctp/debug.c b/net/sctp/debug.c
new file mode 100644
index 000000000..ccd773e4c
--- /dev/null
+++ b/net/sctp/debug.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SCTP kernel implementation
+ * (C) Copyright IBM Corp. 2001, 2004
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001 Intel Corp.
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * This file converts numerical ID value to alphabetical names for SCTP
+ * terms such as chunk type, parameter time, event type, etc.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Karl Knutson          <karl@athena.chicago.il.us>
+ *    Xingang Guo           <xingang.guo@intel.com>
+ *    Jon Grimm             <jgrimm@us.ibm.com>
+ *    Daisy Chang	    <daisyc@us.ibm.com>
+ *    Sridhar Samudrala	    <sri@us.ibm.com>
+ */
+
+#include <net/sctp/sctp.h>
+
+/* These are printable forms of Chunk ID's from section 3.1.  */
+static const char *const sctp_cid_tbl[SCTP_NUM_BASE_CHUNK_TYPES] = {
+	"DATA",
+	"INIT",
+	"INIT_ACK",
+	"SACK",
+	"HEARTBEAT",
+	"HEARTBEAT_ACK",
+	"ABORT",
+	"SHUTDOWN",
+	"SHUTDOWN_ACK",
+	"ERROR",
+	"COOKIE_ECHO",
+	"COOKIE_ACK",
+	"ECN_ECNE",
+	"ECN_CWR",
+	"SHUTDOWN_COMPLETE",
+};
+
+/* Lookup "chunk type" debug name. */
+const char *sctp_cname(const union sctp_subtype cid)
+{
+	if (cid.chunk <= SCTP_CID_BASE_MAX)
+		return sctp_cid_tbl[cid.chunk];
+
+	switch (cid.chunk) {
+	case SCTP_CID_ASCONF:
+		return "ASCONF";
+
+	case SCTP_CID_ASCONF_ACK:
+		return "ASCONF_ACK";
+
+	case SCTP_CID_FWD_TSN:
+		return "FWD_TSN";
+
+	case SCTP_CID_AUTH:
+		return "AUTH";
+
+	case SCTP_CID_RECONF:
+		return "RECONF";
+
+	case SCTP_CID_I_DATA:
+		return "I_DATA";
+
+	case SCTP_CID_I_FWD_TSN:
+		return "I_FWD_TSN";
+
+	default:
+		break;
+	}
+
+	return "unknown chunk";
+}
+
+/* These are printable forms of the states.  */
+const char *const sctp_state_tbl[SCTP_STATE_NUM_STATES] = {
+	"STATE_CLOSED",
+	"STATE_COOKIE_WAIT",
+	"STATE_COOKIE_ECHOED",
+	"STATE_ESTABLISHED",
+	"STATE_SHUTDOWN_PENDING",
+	"STATE_SHUTDOWN_SENT",
+	"STATE_SHUTDOWN_RECEIVED",
+	"STATE_SHUTDOWN_ACK_SENT",
+};
+
+/* Events that could change the state of an association.  */
+const char *const sctp_evttype_tbl[] = {
+	"EVENT_T_unknown",
+	"EVENT_T_CHUNK",
+	"EVENT_T_TIMEOUT",
+	"EVENT_T_OTHER",
+	"EVENT_T_PRIMITIVE"
+};
+
+/* Return value of a state function */
+const char *const sctp_status_tbl[] = {
+	"DISPOSITION_DISCARD",
+	"DISPOSITION_CONSUME",
+	"DISPOSITION_NOMEM",
+	"DISPOSITION_DELETE_TCB",
+	"DISPOSITION_ABORT",
+	"DISPOSITION_VIOLATION",
+	"DISPOSITION_NOT_IMPL",
+	"DISPOSITION_ERROR",
+	"DISPOSITION_BUG"
+};
+
+/* Printable forms of primitives */
+static const char *const sctp_primitive_tbl[SCTP_NUM_PRIMITIVE_TYPES] = {
+	"PRIMITIVE_ASSOCIATE",
+	"PRIMITIVE_SHUTDOWN",
+	"PRIMITIVE_ABORT",
+	"PRIMITIVE_SEND",
+	"PRIMITIVE_REQUESTHEARTBEAT",
+	"PRIMITIVE_ASCONF",
+};
+
+/* Lookup primitive debug name. */
+const char *sctp_pname(const union sctp_subtype id)
+{
+	if (id.primitive <= SCTP_EVENT_PRIMITIVE_MAX)
+		return sctp_primitive_tbl[id.primitive];
+	return "unknown_primitive";
+}
+
+static const char *const sctp_other_tbl[] = {
+	"NO_PENDING_TSN",
+	"ICMP_PROTO_UNREACH",
+};
+
+/* Lookup "other" debug name. */
+const char *sctp_oname(const union sctp_subtype id)
+{
+	if (id.other <= SCTP_EVENT_OTHER_MAX)
+		return sctp_other_tbl[id.other];
+	return "unknown 'other' event";
+}
+
+static const char *const sctp_timer_tbl[] = {
+	"TIMEOUT_NONE",
+	"TIMEOUT_T1_COOKIE",
+	"TIMEOUT_T1_INIT",
+	"TIMEOUT_T2_SHUTDOWN",
+	"TIMEOUT_T3_RTX",
+	"TIMEOUT_T4_RTO",
+	"TIMEOUT_T5_SHUTDOWN_GUARD",
+	"TIMEOUT_HEARTBEAT",
+	"TIMEOUT_RECONF",
+	"TIMEOUT_PROBE",
+	"TIMEOUT_SACK",
+	"TIMEOUT_AUTOCLOSE",
+};
+
+/* Lookup timer debug name. */
+const char *sctp_tname(const union sctp_subtype id)
+{
+	BUILD_BUG_ON(SCTP_EVENT_TIMEOUT_MAX + 1 != ARRAY_SIZE(sctp_timer_tbl));
+
+	if (id.timeout < ARRAY_SIZE(sctp_timer_tbl))
+		return sctp_timer_tbl[id.timeout];
+	return "unknown_timer";
+}