Re: [PATCH] x86/msr: add 64bit _on_cpu access functions

[H. Peter Anvin]

The patch is fine but please use it asa preface to a patch series that actually used these interfaces.

Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> wrote:
>Having 64-bit MSR access methods on given CPU can avoid shifting and
>simplify MSR content manipulation. We already have other combinations
>of rdmsrl_xxx and wrmsrl_xxx but missing the _on_cpu version.
>
>Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
>---
> arch/x86/include/asm/msr.h |   22 ++++++++++++++++
>arch/x86/lib/msr-smp.c     |   62
>++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+)
>
>diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
>index cb75028..e139b13 100644
>--- a/arch/x86/include/asm/msr.h
>+++ b/arch/x86/include/asm/msr.h
>@@ -218,10 +218,14 @@ void msrs_free(struct msr *msrs);
> #ifdef CONFIG_SMP
> int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
> int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
>+int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
>+int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q);
>void rdmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr
>*msrs);
>void wrmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr
>*msrs);
> int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
> int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
>+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]);
> #else  /*  CONFIG_SMP  */
>@@ -235,6 +239,16 @@ static inline int wrmsr_on_cpu(unsigned int cpu,
>u32 msr_no, u32 l, u32 h)
> 	wrmsr(msr_no, l, h);
> 	return 0;
> }
>+static inline int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
>+{
>+	rdmsrl(msr_no, *q);
>+	return 0;
>+}
>+static inline int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
>+{
>+	wrmsrl(msr_no, q);
>+	return 0;
>+}
> static inline void rdmsr_on_cpus(const struct cpumask *m, u32 msr_no,
> 				struct msr *msrs)
> {
>@@ -254,6 +268,14 @@ static inline int wrmsr_safe_on_cpu(unsigned int
>cpu, u32 msr_no, u32 l, u32 h)
> {
> 	return wrmsr_safe(msr_no, l, h);
> }
>+static inline int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64
>*q)
>+{
>+	return rdmsrl_safe(msr_no, q);
>+}
>+static inline int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64
>q)
>+{
>+	return wrmsrl_safe(msr_no, q);
>+}
>static inline int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8])
> {
> 	return rdmsr_safe_regs(regs);
>diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c
>index a6b1b86..518532e 100644
>--- a/arch/x86/lib/msr-smp.c
>+++ b/arch/x86/lib/msr-smp.c
>@@ -47,6 +47,21 @@ int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32
>*l, u32 *h)
> }
> EXPORT_SYMBOL(rdmsr_on_cpu);
> 
>+int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
>+{
>+	int err;
>+	struct msr_info rv;
>+
>+	memset(&rv, 0, sizeof(rv));
>+
>+	rv.msr_no = msr_no;
>+	err = smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 1);
>+	*q = rv.reg.q;
>+
>+	return err;
>+}
>+EXPORT_SYMBOL(rdmsrl_on_cpu);
>+
> int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
> {
> 	int err;
>@@ -63,6 +78,22 @@ int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32
>l, u32 h)
> }
> EXPORT_SYMBOL(wrmsr_on_cpu);
> 
>+int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
>+{
>+	int err;
>+	struct msr_info rv;
>+
>+	memset(&rv, 0, sizeof(rv));
>+
>+	rv.msr_no = msr_no;
>+	rv.reg.q = q;
>+
>+	err = smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 1);
>+
>+	return err;
>+}
>+EXPORT_SYMBOL(wrmsrl_on_cpu);
>+
> static void __rwmsr_on_cpus(const struct cpumask *mask, u32 msr_no,
> 			    struct msr *msrs,
> 			    void (*msr_func) (void *info))
>@@ -159,6 +190,37 @@ int wrmsr_safe_on_cpu(unsigned int cpu, u32
>msr_no, u32 l, u32 h)
> }
> EXPORT_SYMBOL(wrmsr_safe_on_cpu);
> 
>+int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
>+{
>+	int err;
>+	struct msr_info rv;
>+
>+	memset(&rv, 0, sizeof(rv));
>+
>+	rv.msr_no = msr_no;
>+	rv.reg.q = q;
>+
>+	err = smp_call_function_single(cpu, __wrmsr_safe_on_cpu, &rv, 1);
>+
>+	return err ? err : rv.err;
>+}
>+EXPORT_SYMBOL(wrmsrl_safe_on_cpu);
>+
>+int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
>+{
>+	int err;
>+	struct msr_info rv;
>+
>+	memset(&rv, 0, sizeof(rv));
>+
>+	rv.msr_no = msr_no;
>+	err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);
>+	*q = rv.reg.q;
>+
>+	return err ? err : rv.err;
>+}
>+EXPORT_SYMBOL(rdmsrl_safe_on_cpu);
>+
> /*
>  * These variants are significantly slower, but allows control over
>  * the entire 32-bit GPR set.

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