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, 61 insertions, 0 deletions

diff --git a/include/net/wext.h b/include/net/wext.h
new file mode 100644
index 000000000..aa192a670
--- /dev/null
+++ b/include/net/wext.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_WEXT_H
+#define __NET_WEXT_H
+
+#include <net/iw_handler.h>
+
+struct net;
+
+#ifdef CONFIG_WEXT_CORE
+int wext_handle_ioctl(struct net *net, unsigned int cmd,
+		      void __user *arg);
+int compat_wext_handle_ioctl(struct net *net, unsigned int cmd,
+			     unsigned long arg);
+
+struct iw_statistics *get_wireless_stats(struct net_device *dev);
+int call_commit_handler(struct net_device *dev);
+#else
+static inline int wext_handle_ioctl(struct net *net, unsigned int cmd,
+				    void __user *arg)
+{
+	return -EINVAL;
+}
+static inline int compat_wext_handle_ioctl(struct net *net, unsigned int cmd,
+					   unsigned long arg)
+{
+	return -EINVAL;
+}
+#endif
+
+#ifdef CONFIG_WEXT_PROC
+int wext_proc_init(struct net *net);
+void wext_proc_exit(struct net *net);
+#else
+static inline int wext_proc_init(struct net *net)
+{
+	return 0;
+}
+static inline void wext_proc_exit(struct net *net)
+{
+	return;
+}
+#endif
+
+#ifdef CONFIG_WEXT_PRIV
+int ioctl_private_call(struct net_device *dev, struct iwreq *iwr,
+		       unsigned int cmd, struct iw_request_info *info,
+		       iw_handler handler);
+int compat_private_call(struct net_device *dev, struct iwreq *iwr,
+			unsigned int cmd, struct iw_request_info *info,
+			iw_handler handler);
+int iw_handler_get_private(struct net_device *		dev,
+			   struct iw_request_info *	info,
+			   union iwreq_data *		wrqu,
+			   char *			extra);
+#else
+#define ioctl_private_call NULL
+#define compat_private_call NULL
+#endif
+
+
+#endif /* __NET_WEXT_H */