Re: [PATCH] Revert "iommu/arm-smmu: Convert to domain_alloc_paging()"

From: Jason Gunthorpe <jgg@ziepe.ca>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Rob Clark <robdclark@gmail.com>,
	linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
	linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] Revert "iommu/arm-smmu: Convert to domain_alloc_paging()"
Date: Tue, 13 Feb 2024 08:12:57 -0400	[thread overview]
Message-ID: <20240213121257.GI765010@ziepe.ca> (raw)
In-Reply-To: <20240213-iommu-revert-domain-alloc-v1-1-325ff55dece4@linaro.org>

On Tue, Feb 13, 2024 at 01:31:56PM +0200, Dmitry Baryshkov wrote:
> This reverts commit 9b3febc3a3da ("iommu/arm-smmu: Convert to
> domain_alloc_paging()"). It breaks Qualcomm MSM8996 platform. Calling
> arm_smmu_write_context_bank() from new codepath results in the platform
> being reset because of the unclocked hardware access.
> 
> Fixes: 9b3febc3a3da ("iommu/arm-smmu: Convert to domain_alloc_paging()")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)

Please no, as I said in the other email the only thing that should be
reverted is this:

> @@ -875,15 +879,6 @@ static struct iommu_domain *arm_smmu_domain_alloc_paging(struct device *dev)
>  	mutex_init(&smmu_domain->init_mutex);
>  	spin_lock_init(&smmu_domain->cb_lock);
>  
> -	if (dev) {
> -		struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
> -
> -		if (arm_smmu_init_domain_context(smmu_domain, cfg->smmu, dev)) {
> -			kfree(smmu_domain);
> -			return NULL;
> -		}
> -	}
> -
>  	return &smmu_domain->domain;
>  }

Everything else is fine, you already tested with that arrangement.

Jason