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, 29 insertions, 0 deletions

diff --git a/include/rdma/ib_ucaps.h b/include/rdma/ib_ucaps.h
new file mode 100644
index 000000000..b629c9911
--- /dev/null
+++ b/include/rdma/ib_ucaps.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved
+ */
+
+#ifndef _IB_UCAPS_H_
+#define _IB_UCAPS_H_
+
+#define UCAP_ENABLED(ucaps, type) (!!((ucaps) & (1U << (type))))
+
+enum rdma_user_cap {
+	RDMA_UCAP_MLX5_CTRL_LOCAL,
+	RDMA_UCAP_MLX5_CTRL_OTHER_VHCA,
+	RDMA_UCAP_MAX
+};
+
+int ib_get_ucaps(int *fds, int fd_count, uint64_t *idx_mask);
+#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
+int ib_create_ucap(enum rdma_user_cap type);
+void ib_remove_ucap(enum rdma_user_cap type);
+#else
+static inline int ib_create_ucap(enum rdma_user_cap type)
+{
+	return -EOPNOTSUPP;
+}
+static inline void ib_remove_ucap(enum rdma_user_cap type) {}
+#endif /* CONFIG_INFINIBAND_USER_ACCESS */
+
+#endif /* _IB_UCAPS_H_ */