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, 91 insertions, 0 deletions

diff --git a/include/rdma/opa_addr.h b/include/rdma/opa_addr.h
new file mode 100644
index 000000000..c6bfa2640
--- /dev/null
+++ b/include/rdma/opa_addr.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
+/*
+ * Copyright(c) 2017 Intel Corporation.
+ */
+
+#ifndef OPA_ADDR_H
+#define OPA_ADDR_H
+
+#include <rdma/opa_smi.h>
+
+#define	OPA_SPECIAL_OUI		(0x00066AULL)
+#define OPA_MAKE_ID(x)          (cpu_to_be64(OPA_SPECIAL_OUI << 40 | (x)))
+#define OPA_TO_IB_UCAST_LID(x) (((x) >= be16_to_cpu(IB_MULTICAST_LID_BASE)) \
+				? 0 : x)
+#define OPA_GID_INDEX		0x1
+/**
+ * 0xF8 - 4 bits of multicast range and 1 bit for collective range
+ * Example: For 24 bit LID space,
+ * Multicast range: 0xF00000 to 0xF7FFFF
+ * Collective range: 0xF80000 to 0xFFFFFE
+ */
+#define OPA_MCAST_NR 0x4 /* Number of top bits set */
+#define OPA_COLLECTIVE_NR 0x1 /* Number of bits after MCAST_NR */
+
+/**
+ * ib_is_opa_gid: Returns true if the top 24 bits of the gid
+ * contains the OPA_STL_OUI identifier. This identifies that
+ * the provided gid is a special purpose GID meant to carry
+ * extended LID information.
+ *
+ * @gid: The Global identifier
+ */
+static inline bool ib_is_opa_gid(const union ib_gid *gid)
+{
+	return ((be64_to_cpu(gid->global.interface_id) >> 40) ==
+		OPA_SPECIAL_OUI);
+}
+
+/**
+ * opa_get_lid_from_gid: Returns the last 32 bits of the gid.
+ * OPA devices use one of the gids in the gid table to also
+ * store the lid.
+ *
+ * @gid: The Global identifier
+ */
+static inline u32 opa_get_lid_from_gid(const union ib_gid *gid)
+{
+	return be64_to_cpu(gid->global.interface_id) & 0xFFFFFFFF;
+}
+
+/**
+ * opa_is_extended_lid: Returns true if dlid or slid are
+ * extended.
+ *
+ * @dlid: The DLID
+ * @slid: The SLID
+ */
+static inline bool opa_is_extended_lid(__be32 dlid, __be32 slid)
+{
+	if ((be32_to_cpu(dlid) >=
+	     be16_to_cpu(IB_MULTICAST_LID_BASE)) ||
+	    (be32_to_cpu(slid) >=
+	     be16_to_cpu(IB_MULTICAST_LID_BASE)))
+		return true;
+
+	return false;
+}
+
+/* Get multicast lid base */
+static inline u32 opa_get_mcast_base(u32 nr_top_bits)
+{
+	return (be32_to_cpu(OPA_LID_PERMISSIVE) << (32 - nr_top_bits));
+}
+
+/* Check for a valid unicast LID for non-SM traffic types */
+static inline bool rdma_is_valid_unicast_lid(struct rdma_ah_attr *attr)
+{
+	if (attr->type == RDMA_AH_ATTR_TYPE_IB) {
+		if (!rdma_ah_get_dlid(attr) ||
+		    rdma_ah_get_dlid(attr) >=
+		    be16_to_cpu(IB_MULTICAST_LID_BASE))
+			return false;
+	} else if (attr->type == RDMA_AH_ATTR_TYPE_OPA) {
+		if (!rdma_ah_get_dlid(attr) ||
+		    rdma_ah_get_dlid(attr) >=
+		    opa_get_mcast_base(OPA_MCAST_NR))
+			return false;
+	}
+	return true;
+}
+#endif /* OPA_ADDR_H */