From: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
"will@kernel.org" <will@kernel.org>,
"joro@8bytes.org" <joro@8bytes.org>,
"kevin.tian@intel.com" <kevin.tian@intel.com>,
"nicolinc@nvidia.com" <nicolinc@nvidia.com>,
"mshavit@google.com" <mshavit@google.com>,
"eric.auger@redhat.com" <eric.auger@redhat.com>,
"joao.m.martins@oracle.com" <joao.m.martins@oracle.com>,
jiangkunkun <jiangkunkun@huawei.com>,
zhukeqian <zhukeqian1@huawei.com>, Linuxarm <linuxarm@huawei.com>
Subject: RE: [PATCH 4/5] iommu/arm-smmu-v3: Add set_dirty_tracking() support
Date: Thu, 30 Nov 2023 08:56:32 +0000 [thread overview]
Message-ID: <d80cd067b57345609a198aac5780e6af@huawei.com> (raw)
In-Reply-To: <20231129194235.GC436702@nvidia.com>
> -----Original Message-----
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, November 29, 2023 7:43 PM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: iommu@lists.linux.dev; linux-arm-kernel@lists.infradead.org;
> robin.murphy@arm.com; will@kernel.org; joro@8bytes.org;
> kevin.tian@intel.com; nicolinc@nvidia.com; mshavit@google.com;
> eric.auger@redhat.com; joao.m.martins@oracle.com; jiangkunkun
> <jiangkunkun@huawei.com>; zhukeqian <zhukeqian1@huawei.com>;
> Linuxarm <linuxarm@huawei.com>
> Subject: Re: [PATCH 4/5] iommu/arm-smmu-v3: Add set_dirty_tracking()
> support
>
> On Tue, Nov 28, 2023 at 09:49:39AM +0000, Shameer Kolothum wrote:
> > From: Joao Martins <joao.m.martins@oracle.com>
> >
> > Dirty tracking will always be enabled with DBM=1 modifier enabled
> > by default when HD is supported.
>
> Is this trying to say that ARM doesn't have a per-table global enable
> for dirty tracking but instead pre-sets the DBM bit to avoid the cost?
>
Yes. SMMUv3 has per-PTE DBM control and I think the initial RFC had
it walking the PTEs and setting the DBM on set_dirty_tracking(). But it
complicates things if we have to incorporates updating entries for any
new mappings. And it was suggested to keep it enabled here,
https://lore.kernel.org/kvm/2d369e58-8ac0-f263-7b94-fe73917782e1@linux.intel.com/T/#m3be8a185668810fb24a030617f5eaf79a9a32748
> So on smmuv3 to enable we have to clear everything and disable
> continues to pay a penalty since we don't go and mark all things as
> dirty again?
Yes we clear everything on enable. Sorry I didn't get the second part.
We don't mark dirty on disable. How is that different from Intel/AMD?
Thanks,
Shameer
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next prev parent reply other threads:[~2023-11-30 8:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-28 9:49 [PATCH 0/5] iommu/smmuv3: Add IOMMUFD dirty tracking support for SMMUv3 Shameer Kolothum
2023-11-28 9:49 ` [PATCH 1/5] iommu/arm-smmu-v3: Add feature detection for HTTU Shameer Kolothum
2023-11-29 19:49 ` Jason Gunthorpe
2023-11-28 9:49 ` [PATCH 2/5] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping Shameer Kolothum
2023-11-29 19:30 ` Jason Gunthorpe
2023-11-30 9:17 ` Shameerali Kolothum Thodi
2023-11-28 9:49 ` [PATCH 3/5] iommu/arm-smmu-v3: Add read_and_clear_dirty() support Shameer Kolothum
2023-11-29 19:35 ` Jason Gunthorpe
2023-11-30 9:05 ` Shameerali Kolothum Thodi
2023-11-28 9:49 ` [PATCH 4/5] iommu/arm-smmu-v3: Add set_dirty_tracking() support Shameer Kolothum
2023-11-29 19:42 ` Jason Gunthorpe
2023-11-30 8:56 ` Shameerali Kolothum Thodi [this message]
2023-11-30 12:54 ` Jason Gunthorpe
2023-11-30 14:04 ` Shameerali Kolothum Thodi
2023-12-14 16:23 ` Joao Martins
2023-11-28 9:49 ` [PATCH 5/5] iommu/arm-smmu-v3: Enforce dirty tracking in domain attach/alloc Shameer Kolothum
2023-11-29 19:48 ` Jason Gunthorpe
2023-11-30 9:01 ` Shameerali Kolothum Thodi
2023-12-14 16:29 ` Joao Martins
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