Messages in this thread | | | Subject | Re: [PATCH v3 15/22] arm64: capabilities: Change scope of VHE to Boot CPU feature | From | Suzuki K Poulose <> | Date | Thu, 8 Mar 2018 12:10:22 +0000 |
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On 12/02/18 17:17, Dave Martin wrote: > 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?
We don't use the "STRICT" tag anymore. Moreover, I used CRITICAL to indicate that it is special in a way that all the "late" CPUs (in this case all secondaries) should match the "state" of the capability (i.e, both ON and OFF) as that of the boot CPU. I am OK to change it to STRICT.
> > 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...
Good catch. You're right, I will fix it.
> > > Removal of this block for !CONFIG_ARM64_VHE is a change rather than just > refactoring, so the commit message should explain it.
Ok.
Cheers Suzuki
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