Re: [PATCH v4 5/7] iommu/io-pgtable-arm: Add read_and_clear_dirty() support

From: Jason Gunthorpe <jgg@nvidia.com>
To: Shameer Kolothum <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,
	ryan.roberts@arm.com, kevin.tian@intel.com, nicolinc@nvidia.com,
	mshavit@google.com, eric.auger@redhat.com,
	joao.m.martins@oracle.com, jiangkunkun@huawei.com,
	zhukeqian1@huawei.com, linuxarm@huawei.com
Subject: Re: [PATCH v4 5/7] iommu/io-pgtable-arm: Add read_and_clear_dirty() support
Date: Sat, 1 Jun 2024 18:17:01 -0300	[thread overview]
Message-ID: <ZluPzQL/qF9A77du@nvidia.com> (raw)
In-Reply-To: <20240528071831.17560-6-shameerali.kolothum.thodi@huawei.com>

On Tue, May 28, 2024 at 08:18:29AM +0100, Shameer Kolothum wrote:
> .read_and_clear_dirty() IOMMU domain op takes care of reading the dirty
> bits (i.e. PTE has DBM set and AP[2] clear) and marshalling into a
> bitmap of a given page size.
> 
> While reading the dirty bits we also set the PTE AP[2] bit to mark it
> as writeable-clean depending on read_and_clear_dirty() flags.
> 
> PTE states with respect to DBM bit:
> 
>                        DBM bit        AP[2]("RDONLY" bit)
> 1. writable_clean        1                 1
> 2. writable_dirty        1                 0
> 3. read-only             0                 1
> 
> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  drivers/iommu/io-pgtable-arm.c | 114 ++++++++++++++++++++++++++++++++-
>  1 file changed, 112 insertions(+), 2 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason