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, 79 insertions, 0 deletions

diff --git a/io_uring/net.h b/io_uring/net.h
new file mode 100644
index 000000000..51fda715d
--- /dev/null
+++ b/io_uring/net.h
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/net.h>
+#include <linux/uio.h>
+#include <linux/io_uring_types.h>
+#include <uapi/linux/io_uring/bpf_filter.h>
+
+struct io_async_msghdr {
+#if defined(CONFIG_NET)
+	struct iou_vec				vec;
+
+	struct_group(clear,
+		int				namelen;
+		struct iovec			fast_iov;
+		__kernel_size_t			controllen;
+		__kernel_size_t			payloadlen;
+		struct sockaddr __user		*uaddr;
+		struct msghdr			msg;
+		struct sockaddr_storage		addr;
+	);
+#else
+	struct_group(clear);
+#endif
+};
+
+#if defined(CONFIG_NET)
+
+int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_shutdown(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_sendmsg_recvmsg_cleanup(struct io_kiocb *req);
+int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_send(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags);
+int io_recv(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_sendrecv_fail(struct io_kiocb *req);
+
+int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_accept(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_socket(struct io_kiocb *req, unsigned int issue_flags);
+void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req);
+void io_connect_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req);
+
+int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_connect(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags);
+int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_send_zc_cleanup(struct io_kiocb *req);
+
+int io_bind_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_bind(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_listen_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_listen(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_netmsg_cache_free(const void *entry);
+#else
+static inline void io_netmsg_cache_free(const void *entry)
+{
+}
+static inline void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx,
+					  struct io_kiocb *req)
+{
+}
+
+static inline void io_connect_bpf_populate(struct io_uring_bpf_ctx *bctx,
+					   struct io_kiocb *req)
+{
+}
+
+#endif