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, 64 insertions, 0 deletions

diff --git a/include/net/icmp.h b/include/net/icmp.h
new file mode 100644
index 000000000..935ee13d9
--- /dev/null
+++ b/include/net/icmp.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		Definitions for the ICMP module.
+ *
+ * Version:	@(#)icmp.h	1.0.4	05/13/93
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ */
+#ifndef _ICMP_H
+#define	_ICMP_H
+
+#include <linux/icmp.h>
+
+#include <net/inet_sock.h>
+#include <net/snmp.h>
+#include <net/ip.h>
+
+struct icmp_err {
+  int		errno;
+  unsigned int	fatal:1;
+};
+
+extern const struct icmp_err icmp_err_convert[];
+#define ICMP_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.icmp_statistics, field)
+#define __ICMP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->mib.icmp_statistics, field)
+#define ICMPMSGOUT_INC_STATS(net, field)	SNMP_INC_STATS_ATOMIC_LONG((net)->mib.icmpmsg_statistics, field+256)
+#define ICMPMSGIN_INC_STATS(net, field)		SNMP_INC_STATS_ATOMIC_LONG((net)->mib.icmpmsg_statistics, field)
+
+struct dst_entry;
+struct net_proto_family;
+struct sk_buff;
+struct net;
+
+void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
+		 const struct inet_skb_parm *parm);
+static inline void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+	__icmp_send(skb_in, type, code, info, IPCB(skb_in));
+}
+
+#if IS_ENABLED(CONFIG_NF_NAT)
+void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info);
+#else
+static inline void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+	struct inet_skb_parm parm;
+
+	memset(&parm, 0, sizeof(parm));
+	__icmp_send(skb_in, type, code, info, &parm);
+}
+#endif
+
+int icmp_rcv(struct sk_buff *skb);
+int icmp_err(struct sk_buff *skb, u32 info);
+int icmp_init(void);
+void icmp_out_count(struct net *net, unsigned char type);
+bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr);
+
+#endif	/* _ICMP_H */