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From: Joao Martins <joao.m.martins@oracle.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Kevin Tian <kevin.tian@intel.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	kvm@vger.kernel.org, Cornelia Huck <cohuck@redhat.com>,
	iommu@lists.linux-foundation.org,
	Alex Williamson <alex.williamson@redhat.com>,
	Will Deacon <will@kernel.org>,
	David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH RFC 13/19] iommu/arm-smmu-v3: Add feature detection for BBML
Date: Fri, 29 Apr 2022 12:54:58 +0100	[thread overview]
Message-ID: <fdb44064-c4ab-9bd1-f984-e3772b539c13@oracle.com> (raw)
In-Reply-To: <8e897628-61fa-b3fb-b609-44eeda11b45e@arm.com>

On 4/29/22 12:11, Robin Murphy wrote:
> On 2022-04-28 22:09, Joao Martins wrote:
>> From: Kunkun Jiang <jiangkunkun@huawei.com>
>>
>> This detects BBML feature and if SMMU supports it, transfer BBMLx
>> quirk to io-pgtable.
>>
>> BBML1 requires still marking PTE nT prior to performing a
>> translation table update, while BBML2 requires neither break-before-make
>> nor PTE nT bit being set. For dirty tracking it needs to clear
>> the dirty bit so checking BBML2 tells us the prerequisite. See SMMUv3.2
>> manual, section "3.21.1.3 When SMMU_IDR3.BBML == 2 (Level 2)" and
>> "3.21.1.2 When SMMU_IDR3.BBML == 1 (Level 1)"
> 
> You can drop this, and the dependencies on BBML elsewhere, until you get 
> round to the future large-page-splitting work, since that's the only 
> thing this represents. Not much point having the feature flags without 
> an actual implementation, or any users.
> 
OK.

My thinking was that the BBML2 meant *also* that we don't need that break-before-make
thingie upon switching translation table entries. It seems that from what you
say, BBML2 then just refers to this but only on the context of switching between
hugepages/normal pages (?), not in general on all bits of the PTE (which we woud .. upon
switching from writeable-dirty to writeable-clean with DBM-set).
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  reply	other threads:[~2022-04-29 11:55 UTC|newest]

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-28 21:09 [PATCH RFC 00/19] IOMMUFD Dirty Tracking Joao Martins
2022-04-28 21:09 ` [PATCH RFC 01/19] iommu: Add iommu_domain ops for dirty tracking Joao Martins
2022-04-29  7:54   ` Tian, Kevin
2022-04-29 10:44     ` Joao Martins
2022-04-29 12:08   ` Jason Gunthorpe via iommu
2022-04-29 14:26     ` Joao Martins
2022-04-29 14:35       ` Jason Gunthorpe via iommu
2022-04-29 13:40   ` Baolu Lu
2022-04-29 15:27     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 02/19] iommufd: Dirty tracking for io_pagetable Joao Martins
2022-04-29  8:07   ` Tian, Kevin
2022-04-29 10:48     ` Joao Martins
2022-04-29 11:56     ` Jason Gunthorpe via iommu
2022-04-29 14:28       ` Joao Martins
2022-04-29 23:51   ` Baolu Lu
2022-05-02 11:57     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 03/19] iommufd: Dirty tracking data support Joao Martins
2022-04-29  8:12   ` Tian, Kevin
2022-04-29 10:54     ` Joao Martins
2022-04-29 12:09       ` Jason Gunthorpe via iommu
2022-04-29 14:33         ` Joao Martins
2022-04-30  4:11   ` Baolu Lu
2022-05-02 12:06     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 04/19] iommu: Add an unmap API that returns dirtied IOPTEs Joao Martins
2022-04-30  5:12   ` Baolu Lu
2022-05-02 12:22     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 05/19] iommufd: Add a dirty bitmap to iopt_unmap_iova() Joao Martins
2022-04-29 12:14   ` Jason Gunthorpe via iommu
2022-04-29 14:36     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 06/19] iommufd: Dirty tracking IOCTLs for the hw_pagetable Joao Martins
2022-04-28 21:09 ` [PATCH RFC 07/19] iommufd/vfio-compat: Dirty tracking IOCTLs compatibility Joao Martins
2022-04-29 12:19   ` Jason Gunthorpe via iommu
2022-04-29 14:27     ` Joao Martins
2022-04-29 14:36       ` Jason Gunthorpe via iommu
2022-04-29 14:52         ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 08/19] iommufd: Add a test for dirty tracking ioctls Joao Martins
2022-04-28 21:09 ` [PATCH RFC 09/19] iommu/amd: Access/Dirty bit support in IOPTEs Joao Martins
2022-05-31 11:34   ` Suravee Suthikulpanit via iommu
2022-05-31 12:15     ` Baolu Lu
2022-05-31 15:22     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 10/19] iommu/amd: Add unmap_read_dirty() support Joao Martins
2022-05-31 12:39   ` Suravee Suthikulpanit via iommu
2022-05-31 15:51     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 11/19] iommu/amd: Print access/dirty bits if supported Joao Martins
2022-04-28 21:09 ` [PATCH RFC 12/19] iommu/arm-smmu-v3: Add feature detection for HTTU Joao Martins
2022-04-28 21:09 ` [PATCH RFC 13/19] iommu/arm-smmu-v3: Add feature detection for BBML Joao Martins
2022-04-29 11:11   ` Robin Murphy
2022-04-29 11:54     ` Joao Martins [this message]
2022-04-29 12:26       ` Robin Murphy
2022-04-29 14:34         ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 14/19] iommu/arm-smmu-v3: Add read_and_clear_dirty() support Joao Martins
2022-04-28 21:09 ` [PATCH RFC 15/19] iommu/arm-smmu-v3: Add set_dirty_tracking_range() support Joao Martins
2022-04-29  8:28   ` Tian, Kevin
2022-04-29 11:05     ` Joao Martins
2022-04-29 11:19       ` Robin Murphy
2022-04-29 12:06         ` Joao Martins
2022-04-29 12:23           ` Jason Gunthorpe via iommu
2022-04-29 14:45             ` Joao Martins
2022-04-29 16:11               ` Jason Gunthorpe via iommu
2022-04-29 16:40                 ` Joao Martins
2022-04-29 16:46                   ` Jason Gunthorpe via iommu
2022-04-29 19:20                   ` Robin Murphy
2022-05-02 11:52                     ` Joao Martins
2022-05-02 11:57                       ` Joao Martins
2022-05-05  7:25       ` Shameerali Kolothum Thodi via iommu
2022-05-05  9:52         ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 16/19] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping Joao Martins
2022-04-29 11:35   ` Robin Murphy
2022-04-29 12:10     ` Joao Martins
2022-04-29 12:46       ` Robin Murphy
2022-04-28 21:09 ` [PATCH RFC 17/19] iommu/arm-smmu-v3: Add unmap_read_dirty() support Joao Martins
2022-04-29 11:53   ` Robin Murphy
2022-04-28 21:09 ` [PATCH RFC 18/19] iommu/intel: Access/Dirty bit support for SL domains Joao Martins
2022-04-29  9:03   ` Tian, Kevin
2022-04-29 11:20     ` Joao Martins
2022-04-30  6:12   ` Baolu Lu
2022-05-02 12:24     ` Joao Martins
2022-04-28 21:09 ` [PATCH RFC 19/19] iommu/intel: Add unmap_read_dirty() support Joao Martins
2022-04-29  5:45 ` [PATCH RFC 00/19] IOMMUFD Dirty Tracking Tian, Kevin
2022-04-29 10:27   ` Joao Martins
2022-04-29 12:38     ` Jason Gunthorpe via iommu
2022-04-29 15:20       ` Joao Martins
2022-05-05  7:40       ` Tian, Kevin
2022-05-05 14:07         ` Jason Gunthorpe via iommu
2022-05-06  3:51           ` Tian, Kevin
2022-05-06 11:46             ` Jason Gunthorpe via iommu
2022-05-10  1:38               ` Tian, Kevin
2022-05-10 11:50                 ` Joao Martins
2022-05-11  1:17                   ` Tian, Kevin
2022-05-10 13:46                 ` Jason Gunthorpe via iommu
2022-05-11  1:10                   ` Tian, Kevin
2022-05-02 18:11   ` Alex Williamson
2022-05-02 18:52     ` Jason Gunthorpe via iommu
2022-05-03 10:48       ` Joao Martins
2022-05-05  7:42       ` Tian, Kevin
2022-05-05 10:06         ` Joao Martins
2022-05-05 11:03           ` Tian, Kevin
2022-05-05 11:50             ` Joao Martins
2022-05-06  3:14               ` Tian, Kevin
2022-05-05 13:55             ` Jason Gunthorpe via iommu
2022-05-06  3:17               ` Tian, Kevin

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