linux-kernel - Re: [PATCH v2 2/3] iommu: Consolidate pasid dma ownership check

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Message-ID: <ZN8FAKHCzWODGRmC@Asurada-Nvidia>
Date:   Thu, 17 Aug 2023 22:43:28 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
CC:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        "Robin Murphy" <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Kevin Tian <kevin.tian@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        "Yi Liu" <yi.l.liu@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        <iommu@...ts.linux.dev>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] iommu: Consolidate pasid dma ownership check

On Mon, Aug 14, 2023 at 09:17:58AM +0800, Lu Baolu wrote:

> When switching device DMA ownership, it is required that all the device's
> pasid DMA be disabled. This is done by checking if the pasid array of the
> group is empty. Consolidate all the open code into a single helper. No
> intentional functionality change.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/iommu.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index f1eba60e573f..d4a06a37ce39 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -3127,6 +3127,19 @@ static bool iommu_is_default_domain(struct iommu_group *group)
>         return false;
>  }
> 
> +/*
> + * Assert no PASID DMA when claiming or releasing group's DMA ownership.
             ^
	     |...

> + * The device pasid interfaces are only for device drivers that have
> + * claimed the DMA ownership. Return true if no pasid DMA setup, otherwise
> + * return false with a WARN().
> + */
> +static bool assert_pasid_dma_ownership(struct iommu_group *group)

... should it be assert_no_pasid_dma_ownership?

Nic