| Message ID | 20190921135054.142360-2-justin.he@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fix double page fault on arm64 | expand |
On Sat, Sep 21, 2019 at 09:50:52PM +0800, Jia He wrote: > We unconditionally set the HW_AFDBM capability and only enable it on > CPUs which really have the feature. But sometimes we need to know > whether this cpu has the capability of HW AF. So decouple AF from > DBM by new helper cpu_has_hw_af(). > > Reported-by: kbuild test robot <lkp@intel.com> > Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com> > Signed-off-by: Jia He <justin.he@arm.com> > --- > arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index c96ffa4722d3..46caf934ba4e 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -667,6 +667,16 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) > default: return CONFIG_ARM64_PA_BITS; > } > } > + > +/* Decouple AF from AFDBM. */ We could do with a better comment here or just remove it altogether. The aim of the patch was to decouple AF check from the AF+DBM but the comment here should describe what the function does. Maybe something like: "Check whether hardware update of the Access flag is supported". > +static inline bool cpu_has_hw_af(void) > +{ > + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) > + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; > + > + return false; > +} Other than the comment above, Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Hi Catalin > -----Original Message----- > From: Catalin Marinas <catalin.marinas@arm.com> > Sent: 2019年9月24日 0:07 > To: Justin He (Arm Technology China) <Justin.He@arm.com> > Cc: Will Deacon <will@kernel.org>; Mark Rutland > <Mark.Rutland@arm.com>; James Morse <James.Morse@arm.com>; Marc > Zyngier <maz@kernel.org>; Matthew Wilcox <willy@infradead.org>; Kirill A. > Shutemov <kirill.shutemov@linux.intel.com>; linux-arm- > kernel@lists.infradead.org; linux-kernel@vger.kernel.org; linux- > mm@kvack.org; Suzuki Poulose <Suzuki.Poulose@arm.com>; Punit > Agrawal <punitagrawal@gmail.com>; Anshuman Khandual > <Anshuman.Khandual@arm.com>; Alex Van Brunt > <avanbrunt@nvidia.com>; Robin Murphy <Robin.Murphy@arm.com>; > Thomas Gleixner <tglx@linutronix.de>; Andrew Morton <akpm@linux- > foundation.org>; Jérôme Glisse <jglisse@redhat.com>; Ralph Campbell > <rcampbell@nvidia.com>; hejianet@gmail.com; Kaly Xin (Arm Technology > China) <Kaly.Xin@arm.com>; nd <nd@arm.com> > Subject: Re: [PATCH v8 1/3] arm64: cpufeature: introduce helper > cpu_has_hw_af() > > On Sat, Sep 21, 2019 at 09:50:52PM +0800, Jia He wrote: > > We unconditionally set the HW_AFDBM capability and only enable it on > > CPUs which really have the feature. But sometimes we need to know > > whether this cpu has the capability of HW AF. So decouple AF from > > DBM by new helper cpu_has_hw_af(). > > > > Reported-by: kbuild test robot <lkp@intel.com> > > Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com> > > Signed-off-by: Jia He <justin.he@arm.com> > > --- > > arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/arch/arm64/include/asm/cpufeature.h > b/arch/arm64/include/asm/cpufeature.h > > index c96ffa4722d3..46caf934ba4e 100644 > > --- a/arch/arm64/include/asm/cpufeature.h > > +++ b/arch/arm64/include/asm/cpufeature.h > > @@ -667,6 +667,16 @@ static inline u32 > id_aa64mmfr0_parange_to_phys_shift(int parange) > > default: return CONFIG_ARM64_PA_BITS; > > } > > } > > + > > +/* Decouple AF from AFDBM. */ > > We could do with a better comment here or just remove it altogether. The > aim of the patch was to decouple AF check from the AF+DBM but the > comment here should describe what the function does. Maybe something > like: "Check whether hardware update of the Access flag is supported". > Okay, I will update it -- Cheers, Justin (Jia He) > > +static inline bool cpu_has_hw_af(void) > > +{ > > + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) > > + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; > > + > > + return false; > > +} > > Other than the comment above, > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index c96ffa4722d3..46caf934ba4e 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -667,6 +667,16 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) default: return CONFIG_ARM64_PA_BITS; } } + +/* Decouple AF from AFDBM. */ +static inline bool cpu_has_hw_af(void) +{ + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; + + return false; +} + #endif /* __ASSEMBLY__ */ #endif
We unconditionally set the HW_AFDBM capability and only enable it on CPUs which really have the feature. But sometimes we need to know whether this cpu has the capability of HW AF. So decouple AF from DBM by new helper cpu_has_hw_af(). Reported-by: kbuild test robot <lkp@intel.com> Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com> Signed-off-by: Jia He <justin.he@arm.com> --- arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ 1 file changed, 10 insertions(+)