From: Dave Martin <Dave.Martin@arm.com>
To: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: 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,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 05/16] arm64: Add flags to check the safety of a capability for late CPU
Date: Tue, 30 Jan 2018 14:56:37 +0000 [thread overview]
Message-ID: <20180130145636.GE5862@e103592.cambridge.arm.com> (raw)
In-Reply-To: <6313a0f1-ed3c-b5b3-7bbd-5f98862a74c6@arm.com>
On Tue, Jan 30, 2018 at 11:17:38AM +0000, Suzuki K Poulose wrote:
> On 26/01/18 10:10, Dave Martin wrote:
> >On Tue, Jan 23, 2018 at 12:27:58PM +0000, Suzuki K Poulose wrote:
> >>Add two different flags to indicate if the conflict of a capability
> >>on a late CPU with the current system state
> >>
> >> 1) Can a CPU have a capability when the system doesn't have it ?
> >>
> >> Most arm64 features could have this set. While erratum work arounds
> >> cannot have this, as we may miss work arounds.
> >>
> >> 2) Can a CPU miss a capability when the system has it ?
> >> This could be set for arm64 erratum work arounds as we don't
> >> care if a CPU doesn't need the work around. However it should
> >> be clear for features.
> >>
> >>These flags could be added to certain entries based on their nature.
> >>
> >>Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> >>---
> >> arch/arm64/include/asm/cpufeature.h | 35 +++++++++++++++++++++++++++++++----
> >> 1 file changed, 31 insertions(+), 4 deletions(-)
> >>
> >>diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> >>index 4fd5de8ef33e..27d037bb0451 100644
> >>--- a/arch/arm64/include/asm/cpufeature.h
> >>+++ b/arch/arm64/include/asm/cpufeature.h
> >>@@ -94,10 +94,25 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
> >> #define SCOPE_SYSTEM ARM64_CPUCAP_SCOPE_SYSTEM
> >> #define SCOPE_LOCAL_CPU ARM64_CPUCAP_SCOPE_LOCAL_CPU
> >>-/* CPU errata detected at boot time based on feature of one or more CPUs */
> >>-#define ARM64_CPUCAP_STRICT_CPU_LOCAL_ERRATUM (ARM64_CPUCAP_SCOPE_LOCAL_CPU)
> >>-/* CPU feature detected at boot time based on system-wide value of a feature */
> >>-#define ARM64_CPUCAP_BOOT_SYSTEM_FEATURE (ARM64_CPUCAP_SCOPE_SYSTEM)
> >>+/* Is it safe for a late CPU to have this capability when system doesn't already have */
> >>+#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE BIT(2)
> >>+/* Is it safe for a late CPU to miss this capability when system has it */
> >>+#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS BIT(3)
> >
> >Maybe _OPTIONAL and _PERMITTED would be a bit less verbose?
> >
> >Alternatively,
> > ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU
> > ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU
>
> Sounds better than what I have. I have picked them up.
Cool, I had resigned myself to probably not winning that one ;)
Cheers
---Dave
next prev parent reply other threads:[~2018-01-30 14:56 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 12:27 [PATCH 00/16] arm64: Rework cpu capabilities handling Suzuki K Poulose
2018-01-23 12:27 ` [PATCH 01/16] arm64: capabilities: Update prototype for enable call back Suzuki K Poulose
2018-01-23 14:52 ` Dave Martin
2018-01-23 15:38 ` Suzuki K Poulose
2018-01-25 15:36 ` Dave Martin
2018-01-25 16:57 ` Suzuki K Poulose
2018-01-29 16:35 ` Dave Martin
2018-01-23 12:27 ` [PATCH 02/16] arm64: Move errata work around check on boot CPU Suzuki K Poulose
2018-01-23 14:59 ` Dave Martin
2018-01-23 15:07 ` Suzuki K Poulose
2018-01-23 15:11 ` Dave Martin
2018-01-23 12:27 ` [PATCH 03/16] arm64: Move errata capability processing code Suzuki K Poulose
2018-01-23 12:27 ` [PATCH 04/16] arm64: capabilities: Prepare for fine grained capabilities Suzuki K Poulose
2018-01-23 17:33 ` Dave Martin
2018-01-24 18:45 ` Suzuki K Poulose
2018-01-25 13:43 ` Dave Martin
2018-01-25 17:08 ` Suzuki K Poulose
2018-01-25 17:38 ` Dave Martin
2018-01-25 17:33 ` Dave Martin
2018-01-25 17:56 ` Suzuki K Poulose
2018-01-26 10:00 ` Dave Martin
2018-01-26 12:13 ` Suzuki K Poulose
2018-01-23 12:27 ` [PATCH 05/16] arm64: Add flags to check the safety of a capability for late CPU Suzuki K Poulose
2018-01-26 10:10 ` Dave Martin
2018-01-30 11:17 ` Suzuki K Poulose
2018-01-30 14:56 ` Dave Martin [this message]
2018-01-30 15:06 ` Suzuki K Poulose
2018-01-23 12:27 ` [PATCH 06/16] arm64: capabilities: Unify the verification Suzuki K Poulose
2018-01-26 11:08 ` Dave Martin
2018-01-26 12:10 ` Suzuki K Poulose
2018-01-29 16:57 ` Dave Martin
2018-01-23 12:28 ` [PATCH 07/16] arm64: capabilities: Filter the entries based on a given type Suzuki K Poulose
2018-01-26 11:22 ` Dave Martin
2018-01-26 12:21 ` Suzuki K Poulose
2018-01-29 17:06 ` Dave Martin
2018-01-23 12:28 ` [PATCH 08/16] arm64: capabilities: Group handling of features and errata Suzuki K Poulose
2018-01-26 11:47 ` Dave Martin
2018-01-26 12:31 ` Suzuki K Poulose
2018-01-29 17:14 ` Dave Martin
2018-01-29 17:22 ` Suzuki K Poulose
2018-01-30 15:06 ` Dave Martin
2018-01-23 12:28 ` [PATCH 09/16] arm64: capabilities: Introduce strict features based on local CPU Suzuki K Poulose
2018-01-26 12:12 ` Dave Martin
2018-01-30 11:25 ` Suzuki K Poulose
2018-01-23 12:28 ` [PATCH 10/16] arm64: Make KPTI strict CPU local feature Suzuki K Poulose
2018-01-26 12:25 ` Dave Martin
2018-01-26 15:46 ` Suzuki K Poulose
2018-01-29 17:24 ` Dave Martin
2018-01-23 12:28 ` [PATCH 11/16] arm64: errata: Clean up midr range helpers Suzuki K Poulose
2018-01-26 13:50 ` Dave Martin
2018-01-23 12:28 ` [PATCH 12/16] arm64: Add helpers for checking CPU MIDR against a range Suzuki K Poulose
2018-01-26 14:08 ` Dave Martin
2018-01-23 12:28 ` [PATCH 13/16] arm64: Add support for checking errata based on a list of MIDRS Suzuki K Poulose
2018-01-26 14:16 ` Dave Martin
2018-01-26 15:57 ` Suzuki K Poulose
2018-01-30 15:16 ` Dave Martin
2018-01-30 15:38 ` Suzuki K Poulose
2018-01-30 15:58 ` Dave Martin
2018-01-23 12:28 ` [PATCH 14/16] arm64: Add MIDR encoding for Arm Cortex-A55 and Cortex-A35 Suzuki K Poulose
2018-01-23 12:28 ` [PATCH 15/16] arm64: Delay enabling hardware DBM feature Suzuki K Poulose
2018-01-26 14:41 ` Dave Martin
2018-01-26 16:05 ` Suzuki K Poulose
2018-01-30 15:22 ` Dave Martin
2018-01-23 12:28 ` [PATCH 16/16] arm64: Add work around for Arm Cortex-A55 Erratum 1024718 Suzuki K Poulose
2018-01-26 15:33 ` Dave Martin
2018-01-26 16:29 ` Suzuki K Poulose
2018-01-30 15:27 ` Dave Martin
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