| Message ID | 1449873637-24300-2-git-send-email-jacob.jun.pan@linux.intel.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
Jacob, On Fri, 11 Dec 2015, Jacob Pan wrote: > +static inline int rmwmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 mask, u64 bits) > +{ > + int err; > + u64 val; > + > + err = rdmsrl_safe(msr_no, &val); > + if (err) > + goto out; > + > + val &= ~mask; > + val |= bits; > + > + err = wrmsrl_safe(msr_no, val); > +out: > + return err; > +} .... > +static void __rmwmsrl_safe(void *info) > +{ > + int err; > + struct msr_action *ma = info; > + u64 val; > + > + err = rdmsrl_safe(ma->msr_no, &val); > + if (err) > + goto out; > + > + val &= ~ma->mask; > + val |= ma->bits; > + > + err = wrmsrl_safe(ma->msr_no, val); > + > +out: > + ma->err = err; So this is a copy of the above !SMP inline. What's wrong with providing: int rmwmsrl_safe(msr_no, clear_mask, set_mask) in x86/lib/msr.c and make the !SMP variant of rdmsrl_safe_on_cpu() and that variant for the SMP case a simple wrapper around it? static void remote_rmwmsrl_safe(void *info) { struct msr_action *ma = info; return rmwmsrl_safe(ma->msr, ma->clear_mask, ma->set_mask); } No gotos, no pointless code duplication. Just simple. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sun, Dec 20, 2015 at 02:28:48PM +0100, Thomas Gleixner wrote: > So this is a copy of the above !SMP inline. What's wrong with providing: > > int rmwmsrl_safe(msr_no, clear_mask, set_mask) > > in x86/lib/msr.c and make the !SMP variant of rdmsrl_safe_on_cpu() and that > variant for the SMP case a simple wrapper around it? > > static void remote_rmwmsrl_safe(void *info) > { > struct msr_action *ma = info; > > return rmwmsrl_safe(ma->msr, ma->clear_mask, ma->set_mask); > } > > No gotos, no pointless code duplication. Just simple. TBH, I find this new "rmwmsrl" interface (the name is unreadable, btw) silly: It provides a plain read-modify-write on a MSR and nothing more but patch 2 immediately shows that this interface is insufficient for the other cases, i.e. package_power_limit_irq_save() for example, where you need to do something more like check bits or error handling. So there we do smp_call_function_single() with a function which does the MSR accesses and whatever else is needed. So why add the former interface in the first place? Having driver-specific functions do whatever it is required and then using a single IPI to run them is much cleaner than adding that unfortunate function which doesn't really suffice.
On Sun, 20 Dec 2015 14:28:48 +0100 (CET) Thomas Gleixner <tglx@linutronix.de> wrote: > So this is a copy of the above !SMP inline. What's wrong with > providing: > > int rmwmsrl_safe(msr_no, clear_mask, set_mask) > > in x86/lib/msr.c and make the !SMP variant of rdmsrl_safe_on_cpu() > and that variant for the SMP case a simple wrapper around it? > > static void remote_rmwmsrl_safe(void *info) > { > struct msr_action *ma = info; > > return rmwmsrl_safe(ma->msr, ma->clear_mask, ma->set_mask); > } > > No gotos, no pointless code duplication. Just simple. much better, just sent new code in v2. Sorry for the delay. Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 77d8b28..6143a47 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 mask; + u64 bits; + int err; +}; + struct msr_regs_info { u32 *regs; int err; @@ -258,6 +265,7 @@ 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 mask, u64 bits); #else /* CONFIG_SMP */ static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h) { @@ -314,6 +322,22 @@ 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 mask, u64 bits) +{ + int err; + u64 val; + + err = rdmsrl_safe(msr_no, &val); + if (err) + goto out; + + val &= ~mask; + val |= bits; + + err = wrmsrl_safe(msr_no, val); +out: + return err; +} #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..60ed278 100644 --- a/arch/x86/lib/msr-smp.c +++ b/arch/x86/lib/msr-smp.c @@ -221,6 +221,53 @@ int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q) } EXPORT_SYMBOL(rdmsrl_safe_on_cpu); + +static void __rmwmsrl_safe(void *info) +{ + int err; + struct msr_action *ma = info; + u64 val; + + err = rdmsrl_safe(ma->msr_no, &val); + if (err) + goto out; + + val &= ~ma->mask; + val |= ma->bits; + + err = wrmsrl_safe(ma->msr_no, val); + +out: + ma->err = err; +} + +/** + * rmwmsrl_safe_on_cpu: Perform a read/modify/write msr transaction on cpu + * + * @cpu: target cpu + * @msr: msr number + * @mask: bitmask to change + * @bits: 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 mask, u64 bits) +{ + int err; + struct msr_action ma; + + memset(&ma, 0, sizeof(ma)); + + ma.msr_no = msr; + ma.mask = mask; + ma.bits = bits; + + err = smp_call_function_single(cpu, __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.
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 <peterz@infradead.org> Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> --- arch/x86/include/asm/msr.h | 24 +++++++++++++++++++++++ arch/x86/lib/msr-smp.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 71 insertions(+)