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, 116 insertions, 0 deletions

diff --git a/include/math-emu/single.h b/include/math-emu/single.h
new file mode 100644
index 000000000..87f90b0f9
--- /dev/null
+++ b/include/math-emu/single.h
@@ -0,0 +1,116 @@
+/* Software floating-point emulation.
+   Definitions for IEEE Single Precision.
+   Copyright (C) 1997,1998,1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Richard Henderson (rth@cygnus.com),
+		  Jakub Jelinek (jj@ultra.linux.cz),
+		  David S. Miller (davem@redhat.com) and
+		  Peter Maydell (pmaydell@chiark.greenend.org.uk).
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#ifndef    __MATH_EMU_SINGLE_H__
+#define    __MATH_EMU_SINGLE_H__
+
+#if _FP_W_TYPE_SIZE < 32
+#error "Here's a nickel kid.  Go buy yourself a real computer."
+#endif
+
+#define _FP_FRACBITS_S		24
+#define _FP_FRACXBITS_S		(_FP_W_TYPE_SIZE - _FP_FRACBITS_S)
+#define _FP_WFRACBITS_S		(_FP_WORKBITS + _FP_FRACBITS_S)
+#define _FP_WFRACXBITS_S	(_FP_W_TYPE_SIZE - _FP_WFRACBITS_S)
+#define _FP_EXPBITS_S		8
+#define _FP_EXPBIAS_S		127
+#define _FP_EXPMAX_S		255
+#define _FP_QNANBIT_S		((_FP_W_TYPE)1 << (_FP_FRACBITS_S-2))
+#define _FP_IMPLBIT_S		((_FP_W_TYPE)1 << (_FP_FRACBITS_S-1))
+#define _FP_OVERFLOW_S		((_FP_W_TYPE)1 << (_FP_WFRACBITS_S))
+
+/* The implementation of _FP_MUL_MEAT_S and _FP_DIV_MEAT_S should be
+   chosen by the target machine.  */
+
+union _FP_UNION_S
+{
+  float flt;
+  struct {
+#if __BYTE_ORDER == __BIG_ENDIAN
+    unsigned sign : 1;
+    unsigned exp  : _FP_EXPBITS_S;
+    unsigned frac : _FP_FRACBITS_S - (_FP_IMPLBIT_S != 0);
+#else
+    unsigned frac : _FP_FRACBITS_S - (_FP_IMPLBIT_S != 0);
+    unsigned exp  : _FP_EXPBITS_S;
+    unsigned sign : 1;
+#endif
+  } bits __attribute__((packed));
+};
+
+#define FP_DECL_S(X)		_FP_DECL(1,X)
+#define FP_UNPACK_RAW_S(X,val)	_FP_UNPACK_RAW_1(S,X,val)
+#define FP_UNPACK_RAW_SP(X,val)	_FP_UNPACK_RAW_1_P(S,X,val)
+#define FP_PACK_RAW_S(val,X)	_FP_PACK_RAW_1(S,val,X)
+#define FP_PACK_RAW_SP(val,X)		\
+  do {					\
+    if (!FP_INHIBIT_RESULTS)		\
+      _FP_PACK_RAW_1_P(S,val,X);	\
+  } while (0)
+
+#define FP_UNPACK_S(X,val)		\
+  do {					\
+    _FP_UNPACK_RAW_1(S,X,val);		\
+    _FP_UNPACK_CANONICAL(S,1,X);	\
+  } while (0)
+
+#define FP_UNPACK_SP(X,val)		\
+  do {					\
+    _FP_UNPACK_RAW_1_P(S,X,val);	\
+    _FP_UNPACK_CANONICAL(S,1,X);	\
+  } while (0)
+
+#define FP_PACK_S(val,X)		\
+  do {					\
+    _FP_PACK_CANONICAL(S,1,X);		\
+    _FP_PACK_RAW_1(S,val,X);		\
+  } while (0)
+
+#define FP_PACK_SP(val,X)		\
+  do {					\
+    _FP_PACK_CANONICAL(S,1,X);		\
+    if (!FP_INHIBIT_RESULTS)		\
+      _FP_PACK_RAW_1_P(S,val,X);	\
+  } while (0)
+
+#define FP_ISSIGNAN_S(X)		_FP_ISSIGNAN(S,1,X)
+#define FP_NEG_S(R,X)			_FP_NEG(S,1,R,X)
+#define FP_ADD_S(R,X,Y)			_FP_ADD(S,1,R,X,Y)
+#define FP_SUB_S(R,X,Y)			_FP_SUB(S,1,R,X,Y)
+#define FP_MUL_S(R,X,Y)			_FP_MUL(S,1,R,X,Y)
+#define FP_DIV_S(R,X,Y)			_FP_DIV(S,1,R,X,Y)
+#define FP_SQRT_S(R,X)			_FP_SQRT(S,1,R,X)
+#define _FP_SQRT_MEAT_S(R,S,T,X,Q)	_FP_SQRT_MEAT_1(R,S,T,X,Q)
+
+#define FP_CMP_S(r,X,Y,un)	_FP_CMP(S,1,r,X,Y,un)
+#define FP_CMP_EQ_S(r,X,Y)	_FP_CMP_EQ(S,1,r,X,Y)
+
+#define FP_TO_INT_S(r,X,rsz,rsg)	_FP_TO_INT(S,1,r,X,rsz,rsg)
+#define FP_TO_INT_ROUND_S(r,X,rsz,rsg)	_FP_TO_INT_ROUND(S,1,r,X,rsz,rsg)
+#define FP_FROM_INT_S(X,r,rs,rt)	_FP_FROM_INT(S,1,X,r,rs,rt)
+
+#define _FP_FRAC_HIGH_S(X)	_FP_FRAC_HIGH_1(X)
+#define _FP_FRAC_HIGH_RAW_S(X)	_FP_FRAC_HIGH_1(X)
+
+#endif /* __MATH_EMU_SINGLE_H__ */