KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/include/net/secure_seq.h b/include/net/secure_seq.h
new file mode 100644
index 000000000..6f9962291
--- /dev/null
+++ b/include/net/secure_seq.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NET_SECURE_SEQ
+#define _NET_SECURE_SEQ
+
+#include <linux/types.h>
+
+struct net;
+extern struct net init_net;
+
+union tcp_seq_and_ts_off {
+	struct {
+		u32 seq;
+		u32 ts_off;
+	};
+	u64 hash64;
+};
+
+u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
+u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
+			       __be16 dport);
+union tcp_seq_and_ts_off
+secure_tcp_seq_and_ts_off(const struct net *net, __be32 saddr, __be32 daddr,
+			  __be16 sport, __be16 dport);
+
+static inline u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
+				 __be16 sport, __be16 dport)
+{
+	union tcp_seq_and_ts_off ts;
+
+	ts = secure_tcp_seq_and_ts_off(&init_net, saddr, daddr,
+				       sport, dport);
+
+	return ts.seq;
+}
+
+union tcp_seq_and_ts_off
+secure_tcpv6_seq_and_ts_off(const struct net *net, const __be32 *saddr,
+			    const __be32 *daddr,
+			    __be16 sport, __be16 dport);
+
+static inline u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr,
+				   __be16 sport, __be16 dport)
+{
+	union tcp_seq_and_ts_off ts;
+
+	ts = secure_tcpv6_seq_and_ts_off(&init_net, saddr, daddr,
+					 sport, dport);
+
+	return ts.seq;
+}
+#endif /* _NET_SECURE_SEQ */