From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fenghua Yu Subject: [PATCH v6 18/20] x86/clearcpuid: Apply cleared feature bits that are forced set before Date: Wed, 3 Apr 2019 14:22:04 -0700 Message-ID: <1554326526-172295-19-git-send-email-fenghua.yu@intel.com> References: <1554326526-172295-1-git-send-email-fenghua.yu@intel.com> Cc: "linux-kernel" , "x86" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, kvm@vger.kernel.org, Fenghua Yu To: "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "H Peter Anvin" , "Dave Hansen" , "Paolo Bonzini" , "Ashok Raj" , "Peter Zijlstra" , "Kalle Valo" , "Xiaoyao Li " , "Michael Chan" , "Ravi V Shankar" Return-path: In-Reply-To: <1554326526-172295-1-git-send-email-fenghua.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Some CPU feature bits are forced set and stored in cpuinfo_x86 before handling clearcpuid options. To clear those bits from cpuinfo_x86, apply_forced_cap() is called after handling the options. Please note, apply_forced_cap() is called twice on boot CPU. But this code is simple and there is no functionality issue. Signed-off-by: Fenghua Yu --- arch/x86/include/asm/cpu.h | 2 ++ arch/x86/kernel/cpu/common.c | 5 +++-- arch/x86/kernel/fpu/init.c | 2 ++ 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h index 4e03f53fc079..bfa5ac6b7502 100644 --- a/arch/x86/include/asm/cpu.h +++ b/arch/x86/include/asm/cpu.h @@ -26,6 +26,8 @@ struct x86_cpu { struct cpu cpu; }; +void apply_forced_caps(struct cpuinfo_x86 *c); + #ifdef CONFIG_HOTPLUG_CPU extern int arch_register_cpu(int num); extern void arch_unregister_cpu(int); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index bbdd69dd4f5f..e1d41405c27b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -758,13 +758,14 @@ void cpu_detect(struct cpuinfo_x86 *c) } } -static void apply_forced_caps(struct cpuinfo_x86 *c) +void apply_forced_caps(struct cpuinfo_x86 *c) { int i; for (i = 0; i < NCAPINTS + NBUGINTS; i++) { - c->x86_capability[i] &= ~cpu_caps_cleared[i]; + /* Bits may be cleared after they are set. */ c->x86_capability[i] |= cpu_caps_set[i]; + c->x86_capability[i] &= ~cpu_caps_cleared[i]; } } diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 99b895eea166..9c2801b605e3 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -261,6 +262,7 @@ static void __init clear_cpuid(void) bit >= 0 && bit < NCAPINTS * 32) setup_clear_cpu_cap(bit); } + apply_forced_caps(&boot_cpu_data); } /* -- 2.19.1