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/x86/lib/cpu.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 arch/x86/lib/cpu.c (limited to 'arch/x86/lib/cpu.c') diff --git a/arch/x86/lib/cpu.c b/arch/x86/lib/cpu.c new file mode 100644 index 000000000..d39fba72f --- /dev/null +++ b/arch/x86/lib/cpu.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include + +#include +#include + +static unsigned int __x86_family(unsigned int base_fam, unsigned int ext_fam) +{ + if (base_fam == 0xf) + base_fam += ext_fam; + + return base_fam; +} + +static unsigned int __x86_model(unsigned int family, unsigned int base_model, + unsigned int ext_model) +{ + if (family >= 0x6) + base_model |= ext_model << 4; + + return base_model; +} + +unsigned int x86_family(unsigned int sig) +{ + return __x86_family((sig >> 8) & 0xf, (sig >> 20) & 0xff); +} +EXPORT_SYMBOL_GPL(x86_family); + +unsigned int x86_model(unsigned int sig) +{ + return __x86_model(x86_family(sig), (sig >> 4) & 0xf, (sig >> 16) & 0xf); +} +EXPORT_SYMBOL_GPL(x86_model); + +unsigned int x86_stepping(unsigned int sig) +{ + return sig & 0xf; +} +EXPORT_SYMBOL_GPL(x86_stepping); + +unsigned int cpuid_family(const struct leaf_0x1_0 *l) +{ + return __x86_family(l->base_family_id, l->ext_family); +} + +unsigned int cpuid_model(const struct leaf_0x1_0 *l) +{ + return __x86_model(cpuid_family(l), l->base_model, l->ext_model); +} -- cgit v1.3.1