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/asm-generic/syscalls.h b/include/asm-generic/syscalls.h
new file mode 100644
index 000000000..fabcefe8a
--- /dev/null
+++ b/include/asm-generic/syscalls.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_SYSCALLS_H
+#define __ASM_GENERIC_SYSCALLS_H
+
+#include <linux/compiler.h>
+#include <linux/linkage.h>
+
+/*
+ * Calling conventions for these system calls can differ, so
+ * it's possible to override them.
+ */
+
+#ifndef sys_mmap2
+asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
+			unsigned long prot, unsigned long flags,
+			unsigned long fd, unsigned long pgoff);
+#endif
+
+#ifndef sys_mmap
+asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
+			unsigned long prot, unsigned long flags,
+			unsigned long fd, unsigned long off);
+#endif
+
+#ifndef sys_rt_sigreturn
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs);
+#endif
+
+#endif /* __ASM_GENERIC_SYSCALLS_H */