Messages in this thread Patch in this message | | | Date | Mon, 12 Feb 2018 17:17:27 +0000 | From | Dave Martin <> | Subject | Re: [PATCH v3 15/22] arm64: capabilities: Change scope of VHE to Boot CPU feature |
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On Fri, Feb 09, 2018 at 05:54:59PM +0000, Suzuki K Poulose wrote: > We expect all CPUs to be running at the same EL inside the kernel > with or without VHE enabled and we have strict checks to ensure > that any mismatch triggers a kernel panic. If VHE is enabled, > we use the feature based on the boot CPU and all other CPUs > should follow. This makes it a perfect candidate for a cpability
capability
> based on the boot CPU, which should be matched by all the CPUs > (both when is ON and OFF). This saves us some not-so-pretty > hooks and special code, just for verifying the conflict. > > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Dave Martin <dave.martin@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > arch/arm64/include/asm/cpufeature.h | 7 +++++++ > arch/arm64/include/asm/virt.h | 6 ------ > arch/arm64/kernel/cpufeature.c | 5 +++-- > arch/arm64/kernel/smp.c | 38 ------------------------------------- > 4 files changed, 10 insertions(+), 46 deletions(-) > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index 5f56a8342065..dfce93f79ae7 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -276,6 +276,13 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; > (ARM64_CPUCAP_SCOPE_LOCAL_CPU | \ > ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU) > > +/* > + * Critical CPU feature used early in the boot based on the boot CPU. > + * The feature should be matched by all booting CPU (both miss and hit > + * cases). > + */ > +#define ARM64_CPUCAP_CRITICAL_BOOT_CPU_FEATURE ARM64_CPUCAP_SCOPE_BOOT_CPU > +
Nit: would it be consistent with the uses we already have for the word "strict" to use that word here? i.e., ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE. Or do you think that would be more confusing?
Otherwise, "critical" sounds a bit like we depend on the capability being available.
If "strict" doesn't fit though and no other option suggests itself, it's probably not worth changing this.
> struct arm64_cpu_capabilities { > const char *desc; > u16 capability; > diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h > index c5f89442785c..9d1e24e030b3 100644 > --- a/arch/arm64/include/asm/virt.h > +++ b/arch/arm64/include/asm/virt.h > @@ -102,12 +102,6 @@ static inline bool has_vhe(void) > return false; > } > > -#ifdef CONFIG_ARM64_VHE > -extern void verify_cpu_run_el(void); > -#else > -static inline void verify_cpu_run_el(void) {} > -#endif > - > #endif /* __ASSEMBLY__ */ > > #endif /* ! __ASM__VIRT_H */ > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 7625e2962e2b..f66e66c79916 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -1016,11 +1016,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = { > }, > #endif /* CONFIG_ARM64_PAN */ > { > +#ifdef CONFIG_ARM64_VHE > .desc = "Virtualization Host Extensions", > .capability = ARM64_HAS_VIRT_HOST_EXTN, > - .type = ARM64_CPUCAP_SYSTEM_FEATURE, > + .type = ARM64_CPUCAP_CRITICAL_BOOT_CPU_FEATURE, > .matches = runs_at_el2, > .cpu_enable = cpu_copy_el2regs, > +#endif
Shouldn't the #ifdef...#endif be outside the { ... },?
Otherwise this yields an empty block that will truncate the list in the CONFIG_ARM64_VHE case...
Removal of this block for !CONFIG_ARM64_VHE is a change rather than just refactoring, so the commit message should explain it.
[...]
Cheers ---Dave
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