From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes 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 Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/powerpc/lib/div64.S | 55 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 arch/powerpc/lib/div64.S (limited to 'arch/powerpc/lib/div64.S') diff --git a/arch/powerpc/lib/div64.S b/arch/powerpc/lib/div64.S new file mode 100644 index 000000000..3d5426e7d --- /dev/null +++ b/arch/powerpc/lib/div64.S @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Divide a 64-bit unsigned number by a 32-bit unsigned number. + * This routine assumes that the top 32 bits of the dividend are + * non-zero to start with. + * On entry, r3 points to the dividend, which get overwritten with + * the 64-bit quotient, and r4 contains the divisor. + * On exit, r3 contains the remainder. + * + * Copyright (C) 2002 Paul Mackerras, IBM Corp. + */ +#include +#include + +_GLOBAL(__div64_32) + lwz r5,0(r3) # get the dividend into r5/r6 + lwz r6,4(r3) + cmplw r5,r4 + li r7,0 + li r8,0 + blt 1f + divwu r7,r5,r4 # if dividend.hi >= divisor, + mullw r0,r7,r4 # quotient.hi = dividend.hi / divisor + subf. r5,r0,r5 # dividend.hi %= divisor + beq 3f +1: mr r11,r5 # here dividend.hi != 0 + andis. r0,r5,0xc000 + bne 2f + cntlzw r0,r5 # we are shifting the dividend right + li r10,-1 # to make it < 2^32, and shifting + srw r10,r10,r0 # the divisor right the same amount, + addc r9,r4,r10 # rounding up (so the estimate cannot + andc r11,r6,r10 # ever be too large, only too small) + andc r9,r9,r10 + addze r9,r9 + or r11,r5,r11 + rotlw r9,r9,r0 + rotlw r11,r11,r0 + divwu r11,r11,r9 # then we divide the shifted quantities +2: mullw r10,r11,r4 # to get an estimate of the quotient, + mulhwu r9,r11,r4 # multiply the estimate by the divisor, + subfc r6,r10,r6 # take the product from the divisor, + add r8,r8,r11 # and add the estimate to the accumulated + subfe. r5,r9,r5 # quotient + bne 1b +3: cmplw r6,r4 + blt 4f + divwu r0,r6,r4 # perform the remaining 32-bit division + mullw r10,r0,r4 # and get the remainder + add r8,r8,r0 + subf r6,r10,r6 +4: stw r7,0(r3) # return the quotient in *r3 + stw r8,4(r3) + mr r3,r6 # return the remainder in r3 + blr -- cgit v1.3.1