From: Suzuki K Poulose <Suzuki.Poulose@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, will.deacon@arm.com,
dave.martin@arm.com, catalin.marinas@arm.com,
marc.zyngier@arm.com, mark.rutland@arm.com,
ard.biesheuvel@linaro.org, jnair@caviumnetworks.com,
ckadabi@codeaurora.org, robin.murphy@arm.com,
shankerd@codeaurora.org
Subject: Re: [PATCH v4 19/22] arm64: capabilities: Handle shared entries
Date: Thu, 22 Mar 2018 16:43:28 +0000 [thread overview]
Message-ID: <6a7c55b2-a5a5-c672-1b85-5ba9c8e8560b@arm.com> (raw)
In-Reply-To: <20180313115120.17256-20-suzuki.poulose@arm.com>
On 13/03/18 11:51, Suzuki K Poulose wrote:
> Some capabilities have different criteria for detection and associated
> actions based on the matching criteria, even though they all share the
> same capability bit. So far we have used multiple entries with the same
> capability bit to handle this. This is prone to errors, as the
> cpu_enable is invoked for each entry, irrespective of whether the
> detection rule applies to the CPU or not. And also this complicates
> other helpers, e.g, __this_cpu_has_cap.
>
> This patch adds a wrapper entry to cover all the possible variations
> of a capability by maintaining list of matches + cpu_enable callbacks.
> To avoid complicating the prototypes for the "matches()", we use
> arm64_cpu_capabilities maintain the list and we ignore all the other
> fields except the matches & cpu_enable.
>
> This ensures :
>
> 1) The capabilitiy is set when at least one of the entry detects
> 2) Action is only taken for the entries that "matches".
>
> This avoids explicit checks in the cpu_enable() take some action.
> The only constraint here is that, all the entries should have the
> same "type" (i.e, scope and conflict rules).
>
> If a cpu_enable() method is associated with multiple matches for a
> single capability, care should be taken that either the match criteria
> are mutually exclusive, or that the method is robust against being
> called multiple times.
>
> This also reverts the changes introduced by commit 67948af41f2e6818ed
> ("arm64: capabilities: Handle duplicate entries for a capability").
>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Reviewed-by: Dave Martin <dave.martin@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Lost changelog:
Changes since v3
- Rename cap_list => match_list
- Address other comments from Dave
- Added Reviewed-by from Dave
Cheers
Suzuki
next prev parent reply other threads:[~2018-03-22 16:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 11:50 [PATCH v4 00/22] arm64: Rework cpu capabilities handling Suzuki K Poulose
2018-03-13 11:50 ` [PATCH v4 01/22] arm64: capabilities: Update prototype for enable call back Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 02/22] arm64: capabilities: Move errata work around check on boot CPU Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 03/22] arm64: capabilities: Move errata processing code Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 04/22] arm64: capabilities: Prepare for fine grained capabilities Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 05/22] arm64: capabilities: Add flags to handle the conflicts on late CPU Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 06/22] arm64: capabilities: Unify the verification Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 07/22] arm64: capabilities: Filter the entries based on a given mask Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 08/22] arm64: capabilities: Prepare for grouping features and errata work arounds Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 09/22] arm64: capabilities: Split the processing of " Suzuki K Poulose
2018-03-22 16:44 ` Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 10/22] arm64: capabilities: Allow features based on local CPU scope Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 11/22] arm64: capabilities: Group handling of features and errata workarounds Suzuki K Poulose
2018-03-21 15:07 ` Dave Martin
2018-03-13 11:51 ` [PATCH v4 12/22] arm64: capabilities: Introduce weak features based on local CPU Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 13/22] arm64: capabilities: Restrict KPTI detection to boot-time CPUs Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 14/22] arm64: capabilities: Add support for features enabled early Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 15/22] arm64: capabilities: Change scope of VHE to Boot CPU feature Suzuki K Poulose
2018-03-21 15:18 ` Dave Martin
2018-03-13 11:51 ` [PATCH v4 16/22] arm64: capabilities: Clean up midr range helpers Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 17/22] arm64: Add helpers for checking CPU MIDR against a range Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 18/22] arm64: capabilities: Add support for checks based on a list of MIDRs Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 19/22] arm64: capabilities: Handle shared entries Suzuki K Poulose
2018-03-22 16:43 ` Suzuki K Poulose [this message]
2018-03-13 11:51 ` [PATCH v4 20/22] arm64: Add MIDR encoding for Arm Cortex-A55 and Cortex-A35 Suzuki K Poulose
2018-03-13 11:51 ` [PATCH v4 21/22] arm64: Delay enabling hardware DBM feature Suzuki K Poulose
2018-03-21 15:22 ` Dave Martin
2018-03-13 11:51 ` [PATCH v4 22/22] arm64: Add work around for Arm Cortex-A55 Erratum 1024718 Suzuki K Poulose
2018-03-21 15:31 ` Dave Martin
2018-03-22 16:42 ` Suzuki K Poulose
2018-03-26 11:53 ` [PATCH v4 00/22] arm64: Rework cpu capabilities handling Will Deacon
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