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Date: Thu, 6 Apr 2023 11:53:53 +0800
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Cc: baolu.lu@linux.intel.com, Kevin Tian <kevin.tian@intel.com>,
 Nicolin Chen <nicolinc@nvidia.com>
Subject: Re: [PATCH v3 15/17] iommu: Allow IOMMU_RESV_DIRECT to work on ARM
Content-Language: en-US
To: Jason Gunthorpe <jgg@nvidia.com>, iommu@lists.linux.dev,
 Joerg Roedel <joro@8bytes.org>, llvm@lists.linux.dev,
 Nathan Chancellor <nathan@kernel.org>,
 Nick Desaulniers <ndesaulniers@google.com>, Miguel Ojeda <ojeda@kernel.org>,
 Robin Murphy <robin.murphy@arm.com>, Tom Rix <trix@redhat.com>,
 Will Deacon <will@kernel.org>
References: <15-v3-e89a9bb522f5+8c87-iommu_err_unwind_jgg@nvidia.com>
From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <15-v3-e89a9bb522f5+8c87-iommu_err_unwind_jgg@nvidia.com>
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On 4/6/23 7:38 AM, Jason Gunthorpe wrote:
> For now several ARM drivers do not allow mappings to be created until a
> domain is attached. This means they do not technically support
> IOMMU_RESV_DIRECT as it requires the 1:1 maps to work continuously.
> 
> Currently if the platform requests these maps on ARM systems they are
> silently ignored.
> 
> Work around this by trying again to establish the direct mappings after
> the domain is attached if the pre-attach attempt failed.
> 
> In the long run the drivers will be fixed to fully setup domains when they
> are created without waiting for attachment.
> 
> Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu