From: Will Deacon <will@kernel.org>
To: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Joerg Roedel <joro@8bytes.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
iommu <iommu@lists.linux-foundation.org>,
Robin Murphy <robin.murphy@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 0/3] perf/smmuv3: Don't reserve the PMCG register spaces
Date: Thu, 28 Jan 2021 20:31:49 +0000 [thread overview]
Message-ID: <20210128203148.GG3016@willie-the-truck> (raw)
In-Reply-To: <20210127113258.1421-1-thunder.leizhen@huawei.com>
On Wed, Jan 27, 2021 at 07:32:55PM +0800, Zhen Lei wrote:
> v2 --> v3:
> Patch 3 is updated because https://lkml.org/lkml/2021/1/22/532 has been queued in advance.
>
> v1 --> v2:
> According to Robin Murphy's suggestion: https://lkml.org/lkml/2021/1/20/470
> Don't reserve the PMCG register spaces, and reserve the entire SMMU register space.
>
> v1:
> Since the PMCG may implement its resigters space(4KB Page0 and 4KB Page1)
> within the SMMUv3 64KB Page0. In this case, when the SMMUv3 driver reserves the
> 64KB Page0 resource in advance, the PMCG driver try to reserve its Page0 and
> Page1 resources, a resource conflict occurs.
>
> commit 52f3fab0067d6fa ("iommu/arm-smmu-v3: Don't reserve implementation
> defined register space") reduce the resource reservation range of the SMMUv3
> driver, it only reserves the first 0xe00 bytes in the 64KB Page0, to avoid
> the above-mentioned resource conflicts.
>
> But the SMMUv3.3 add support for ECMDQ, its registers space is also implemented
> in the SMMUv3 64KB Page0. This means we need to build two separate mappings.
> New features may be added in the future, and more independent mappings may be
> required. The simple problem is complicated because the user expects to map the
> entire SMMUv3 64KB Page0.
>
> Therefore, the proper solution is: If the PMCG register resources are located in
> the 64KB Page0 of the SMMU, the PMCG driver does not reserve the conflict resources
> when the SMMUv3 driver has reserved the conflict resources before. Instead, the PMCG
> driver only performs devm_ioremap() to ensure that it can work properly.
>
> Zhen Lei (3):
> perf/smmuv3: Don't reserve the PMCG register spaces
> perf/smmuv3: Add a MODULE_SOFTDEP() to indicate dependency on SMMU
> iommu/arm-smmu-v3: Reserving the entire SMMU register space
I'll need Robin's ack on these.
Will
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next prev parent reply other threads:[~2021-01-28 20:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 11:32 [PATCH v3 0/3] perf/smmuv3: Don't reserve the PMCG register spaces Zhen Lei
2021-01-27 11:32 ` [PATCH v3 1/3] " Zhen Lei
2021-01-29 15:06 ` Robin Murphy
2021-01-30 2:23 ` Leizhen (ThunderTown)
2021-01-27 11:32 ` [PATCH v3 2/3] perf/smmuv3: Add a MODULE_SOFTDEP() to indicate dependency on SMMU Zhen Lei
2021-01-29 15:12 ` Robin Murphy
2021-01-29 15:34 ` John Garry
2021-01-29 17:03 ` Robin Murphy
2021-01-30 1:34 ` Leizhen (ThunderTown)
2021-01-27 11:32 ` [PATCH v3 3/3] iommu/arm-smmu-v3: Reserving the entire SMMU register space Zhen Lei
2021-01-29 15:27 ` Robin Murphy
2021-01-30 1:54 ` Leizhen (ThunderTown)
2021-02-01 11:44 ` Robin Murphy
2021-02-01 12:00 ` Leizhen (ThunderTown)
2021-01-28 20:31 ` Will Deacon [this message]
2021-01-29 13:15 ` [PATCH v3 0/3] perf/smmuv3: Don't reserve the PMCG register spaces Leizhen (ThunderTown)
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