From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Pan Subject: [PATCH v2 1/2] x86/msr: add on cpu read/modify/write function Date: Tue, 12 Jan 2016 17:11:22 -0800 Message-ID: <1452647483-14244-2-git-send-email-jacob.jun.pan@linux.intel.com> References: <1452647483-14244-1-git-send-email-jacob.jun.pan@linux.intel.com> Return-path: Received: from mga11.intel.com ([192.55.52.93]:53369 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751500AbcAMBNQ (ORCPT ); Tue, 12 Jan 2016 20:13:16 -0500 In-Reply-To: <1452647483-14244-1-git-send-email-jacob.jun.pan@linux.intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: LKML , Linux PM , Rafael Wysocki , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , X86 Kernel Cc: Srinivas Pandruvada , Peter Zijlstra , Jacob Pan Remote CPU read/modify/write is often needed but currently without a lib call. This patch adds an API to perform on CPU safe read/modify/write so that callers don't have to invent such function. Based on initial code from: Peter Zijlstra Suggested-by: Srinivas Pandruvada Signed-off-by: Jacob Pan --- arch/x86/include/asm/msr.h | 13 +++++++++++++ arch/x86/lib/msr-smp.c | 34 ++++++++++++++++++++++++++++++++++ arch/x86/lib/msr.c | 18 ++++++++++++++++++ 3 files changed, 65 insertions(+) diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 77d8b28..c771abd 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -27,6 +27,13 @@ struct msr_info { int err; }; +struct msr_action { + u32 msr_no; + u64 clear_mask; + u64 set_mask; + int err; +}; + struct msr_regs_info { u32 *regs; int err; @@ -244,6 +251,7 @@ struct msr *msrs_alloc(void); void msrs_free(struct msr *msrs); int msr_set_bit(u32 msr, u8 bit); int msr_clear_bit(u32 msr, u8 bit); +int msr_rmwl_safe(u32 msr_no, u64 clear_mask, u64 set_mask); #ifdef CONFIG_SMP int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h); @@ -258,6 +266,7 @@ int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q); int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q); int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]); int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]); +int rmwmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 clear_mask, u64 set_mask); #else /* CONFIG_SMP */ static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h) { @@ -314,6 +323,10 @@ static inline int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]) { return wrmsr_safe_regs(regs); } +static inline int rmwmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 clear_mask, u64 set_mask) +{ + return msr_rmwl_safe(msr_no, clear_mask, set_mask); +} #endif /* CONFIG_SMP */ #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_MSR_H */ diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c index 518532e..468d891 100644 --- a/arch/x86/lib/msr-smp.c +++ b/arch/x86/lib/msr-smp.c @@ -221,6 +221,40 @@ int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q) } EXPORT_SYMBOL(rdmsrl_safe_on_cpu); +static void remote_rmwmsrl_safe(void *info) +{ + struct msr_action *ma = info; + + ma->err = msr_rmwl_safe(ma->msr_no, ma->clear_mask, ma->set_mask); +} + +/** + * rmwmsrl_safe_on_cpu: Perform a read/modify/write msr transaction on cpu + * + * @cpu: target cpu + * @msr: msr number + * @clear_mask: bitmask to change + * @set_mask: bits value for the mask + * + * Returns zero for success, a negative number on error. + */ +int rmwmsrl_safe_on_cpu(unsigned int cpu, u32 msr, u64 clear_mask, u64 set_mask) +{ + int err; + struct msr_action ma; + + memset(&ma, 0, sizeof(ma)); + + ma.msr_no = msr; + ma.clear_mask = clear_mask; + ma.set_mask = set_mask; + + err = smp_call_function_single(cpu, remote_rmwmsrl_safe, &ma, 1); + + return err ? err : ma.err; +} +EXPORT_SYMBOL(rmwmsrl_safe_on_cpu); + /* * These variants are significantly slower, but allows control over * the entire 32-bit GPR set. diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c index 4362373..6e12e8d 100644 --- a/arch/x86/lib/msr.c +++ b/arch/x86/lib/msr.c @@ -108,3 +108,21 @@ int msr_clear_bit(u32 msr, u8 bit) { return __flip_bit(msr, bit, false); } + +int msr_rmwl_safe(u32 msr_no, u64 clear_mask, u64 set_mask) +{ + int err; + u64 val; + + err = rdmsrl_safe(msr_no, &val); + if (err) + goto out; + + val &= ~clear_mask; + val |= set_mask; + + err = wrmsrl_safe(msr_no, val); + +out: + return err; +} -- 1.9.1