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, 23 insertions, 0 deletions

diff --git a/io_uring/timeout.h b/io_uring/timeout.h
new file mode 100644
index 000000000..1620f94dd
--- /dev/null
+++ b/io_uring/timeout.h
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+
+struct io_timeout_data {
+	struct io_kiocb			*req;
+	struct hrtimer			timer;
+	ktime_t				time;
+	enum hrtimer_mode		mode;
+	u32				flags;
+};
+
+__cold void io_flush_timeouts(struct io_ring_ctx *ctx);
+struct io_cancel_data;
+int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd);
+__cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
+			     bool cancel_all);
+void io_queue_linked_timeout(struct io_kiocb *req);
+void io_disarm_next(struct io_kiocb *req);
+
+int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_link_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_timeout(struct io_kiocb *req, unsigned int issue_flags);
+int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags);