| Message ID | 20190401104515.39775-7-andrew.murray@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: Initial support for CVADP | expand |
On Mon, Apr 01, 2019 at 11:45:14AM +0100, Andrew Murray wrote: > Advertise ARM64_HAS_DCPOP when both DC CVAP and DC CVADP are supported. Do you mean ARM64_HAS_DCPODP? And do we need this? This capability flag doesn't currently appear to be used for anything (which makes me wonder whether it _should_ be wired up to something in the kernel). Do we expect the kernel to do something special with this in the future? OTOH, we get a nice printk when the feature is detected, and the code size cost is insignificant. So, if there's a reasonable expectation that we will use it someday, I don't see a big problem with having it. Cheers ---Dave > > Signed-off-by: Andrew Murray <andrew.murray@arm.com> > --- > arch/arm64/include/asm/cpucaps.h | 3 ++- > arch/arm64/kernel/cpufeature.c | 9 +++++++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h > index f6a76e43f39e..defdc67d9ab4 100644 > --- a/arch/arm64/include/asm/cpucaps.h > +++ b/arch/arm64/include/asm/cpucaps.h > @@ -61,7 +61,8 @@ > #define ARM64_HAS_GENERIC_AUTH_ARCH 40 > #define ARM64_HAS_GENERIC_AUTH_IMP_DEF 41 > #define ARM64_HAS_IRQ_PRIO_MASKING 42 > +#define ARM64_HAS_DCPODP 43 > > -#define ARM64_NCAPS 43 > +#define ARM64_NCAPS 44 > > #endif /* __ASM_CPUCAPS_H */ > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 5e27d2dbe45e..c74b25895c43 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -1339,6 +1339,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = { > .field_pos = ID_AA64ISAR1_DPB_SHIFT, > .min_field_value = 1, > }, > + { > + .desc = "Data cache clean to Point of Deep Persistence", > + .capability = ARM64_HAS_DCPODP, > + .type = ARM64_CPUCAP_SYSTEM_FEATURE, > + .matches = has_cpuid_feature, > + .sys_reg = SYS_ID_AA64ISAR1_EL1, > + .field_pos = ID_AA64ISAR1_DPB_SHIFT, > + .min_field_value = 2, > + }, > #endif > #ifdef CONFIG_ARM64_SVE > { > -- > 2.21.0 >
On Tue, Apr 02, 2019 at 03:59:58PM +0100, Dave Martin wrote: > On Mon, Apr 01, 2019 at 11:45:14AM +0100, Andrew Murray wrote: > > Advertise ARM64_HAS_DCPOP when both DC CVAP and DC CVADP are supported. > > Do you mean ARM64_HAS_DCPODP? Yes I did - good catch. > > And do we need this? This capability flag doesn't currently appear to > be used for anything (which makes me wonder whether it _should_ be wired > up to something in the kernel). > > Do we expect the kernel to do something special with this in the future? > > OTOH, we get a nice printk when the feature is detected, and the code > size cost is insignificant. So, if there's a reasonable expectation that > we will use it someday, I don't see a big problem with having it. Yes it's not currently used, so I'm happy to drop this patch if people prefer that - however it does complement the existing DCPOP cap which is present. Thanks, Andrew Murray > > Cheers > ---Dave > > > > > Signed-off-by: Andrew Murray <andrew.murray@arm.com> > > --- > > arch/arm64/include/asm/cpucaps.h | 3 ++- > > arch/arm64/kernel/cpufeature.c | 9 +++++++++ > > 2 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h > > index f6a76e43f39e..defdc67d9ab4 100644 > > --- a/arch/arm64/include/asm/cpucaps.h > > +++ b/arch/arm64/include/asm/cpucaps.h > > @@ -61,7 +61,8 @@ > > #define ARM64_HAS_GENERIC_AUTH_ARCH 40 > > #define ARM64_HAS_GENERIC_AUTH_IMP_DEF 41 > > #define ARM64_HAS_IRQ_PRIO_MASKING 42 > > +#define ARM64_HAS_DCPODP 43 > > > > -#define ARM64_NCAPS 43 > > +#define ARM64_NCAPS 44 > > > > #endif /* __ASM_CPUCAPS_H */ > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > > index 5e27d2dbe45e..c74b25895c43 100644 > > --- a/arch/arm64/kernel/cpufeature.c > > +++ b/arch/arm64/kernel/cpufeature.c > > @@ -1339,6 +1339,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = { > > .field_pos = ID_AA64ISAR1_DPB_SHIFT, > > .min_field_value = 1, > > }, > > + { > > + .desc = "Data cache clean to Point of Deep Persistence", > > + .capability = ARM64_HAS_DCPODP, > > + .type = ARM64_CPUCAP_SYSTEM_FEATURE, > > + .matches = has_cpuid_feature, > > + .sys_reg = SYS_ID_AA64ISAR1_EL1, > > + .field_pos = ID_AA64ISAR1_DPB_SHIFT, > > + .min_field_value = 2, > > + }, > > #endif > > #ifdef CONFIG_ARM64_SVE > > { > > -- > > 2.21.0 > >
On Wed, Apr 03, 2019 at 10:23:42AM +0100, Andrew Murray wrote: > On Tue, Apr 02, 2019 at 03:59:58PM +0100, Dave Martin wrote: > > On Mon, Apr 01, 2019 at 11:45:14AM +0100, Andrew Murray wrote: > > > Advertise ARM64_HAS_DCPOP when both DC CVAP and DC CVADP are supported. > > > > Do you mean ARM64_HAS_DCPODP? > > Yes I did - good catch. > > > > > And do we need this? This capability flag doesn't currently appear to > > be used for anything (which makes me wonder whether it _should_ be wired > > up to something in the kernel). > > > > Do we expect the kernel to do something special with this in the future? > > > > OTOH, we get a nice printk when the feature is detected, and the code > > size cost is insignificant. So, if there's a reasonable expectation that > > we will use it someday, I don't see a big problem with having it. > > Yes it's not currently used, so I'm happy to drop this patch if people prefer > that - however it does complement the existing DCPOP cap which is present. OK, sounds fine. Maybe add a note in the commit message that this is here for consistency with DCPOP, and we anticipate it being used in the future. Cheers ---Dave
On Wed, Apr 03, 2019 at 10:32:43AM +0100, Dave Martin wrote: > On Wed, Apr 03, 2019 at 10:23:42AM +0100, Andrew Murray wrote: > > On Tue, Apr 02, 2019 at 03:59:58PM +0100, Dave Martin wrote: > > > On Mon, Apr 01, 2019 at 11:45:14AM +0100, Andrew Murray wrote: > > > > Advertise ARM64_HAS_DCPOP when both DC CVAP and DC CVADP are supported. > > > > > > Do you mean ARM64_HAS_DCPODP? > > > > Yes I did - good catch. > > > > > > > > And do we need this? This capability flag doesn't currently appear to > > > be used for anything (which makes me wonder whether it _should_ be wired > > > up to something in the kernel). > > > > > > Do we expect the kernel to do something special with this in the future? > > > > > > OTOH, we get a nice printk when the feature is detected, and the code > > > size cost is insignificant. So, if there's a reasonable expectation that > > > we will use it someday, I don't see a big problem with having it. > > > > Yes it's not currently used, so I'm happy to drop this patch if people prefer > > that - however it does complement the existing DCPOP cap which is present. > > OK, sounds fine. > > Maybe add a note in the commit message that this is here for consistency > with DCPOP, and we anticipate it being used in the future. OK thanks, Andrew Murray > > Cheers > ---Dave
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index f6a76e43f39e..defdc67d9ab4 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -61,7 +61,8 @@ #define ARM64_HAS_GENERIC_AUTH_ARCH 40 #define ARM64_HAS_GENERIC_AUTH_IMP_DEF 41 #define ARM64_HAS_IRQ_PRIO_MASKING 42 +#define ARM64_HAS_DCPODP 43 -#define ARM64_NCAPS 43 +#define ARM64_NCAPS 44 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 5e27d2dbe45e..c74b25895c43 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1339,6 +1339,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .field_pos = ID_AA64ISAR1_DPB_SHIFT, .min_field_value = 1, }, + { + .desc = "Data cache clean to Point of Deep Persistence", + .capability = ARM64_HAS_DCPODP, + .type = ARM64_CPUCAP_SYSTEM_FEATURE, + .matches = has_cpuid_feature, + .sys_reg = SYS_ID_AA64ISAR1_EL1, + .field_pos = ID_AA64ISAR1_DPB_SHIFT, + .min_field_value = 2, + }, #endif #ifdef CONFIG_ARM64_SVE {
Advertise ARM64_HAS_DCPOP when both DC CVAP and DC CVADP are supported. Signed-off-by: Andrew Murray <andrew.murray@arm.com> --- arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/kernel/cpufeature.c | 9 +++++++++ 2 files changed, 11 insertions(+), 1 deletion(-)