From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753237AbeBLRRe (ORCPT ); Mon, 12 Feb 2018 12:17:34 -0500 Received: from foss.arm.com ([217.140.101.70]:43832 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753058AbeBLRRc (ORCPT ); Mon, 12 Feb 2018 12:17:32 -0500 Date: Mon, 12 Feb 2018 17:17:27 +0000 From: Dave Martin To: Suzuki K Poulose Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, ckadabi@codeaurora.org, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, jnair@caviumnetworks.com, robin.murphy@arm.com Subject: Re: [PATCH v3 15/22] arm64: capabilities: Change scope of VHE to Boot CPU feature Message-ID: <20180212171727.GL5862@e103592.cambridge.arm.com> References: <20180209175513.17100-1-suzuki.poulose@arm.com> <20180209175513.17100-30-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180209175513.17100-30-suzuki.poulose@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Cc: Dave Martin > Cc: Will Deacon > Signed-off-by: Suzuki K Poulose > --- > 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