linux-kernel - Re: [PATCH v2 9/9] iommu/vt-d: Store guest PASID during bind

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Date:   Tue, 1 Sep 2020 19:08:44 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.pan.linux@...il.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>, Wu Hao <hao.wu@...el.com>
Subject: Re: [PATCH v2 9/9] iommu/vt-d: Store guest PASID during bind

Hi Jacob,
On 8/22/20 6:35 AM, Jacob Pan wrote:
> IOASID core maintains the guest-host mapping in the form of SPID and
> IOASID. This patch assigns the guest PASID (if valid) as SPID while
> binding guest page table with a host PASID. This mapping will be used
> for lookup and notifications.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>  drivers/iommu/intel/svm.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index d8a5efa75095..4c958b1aec4c 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -406,6 +406,7 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
>  		if (data->flags & IOMMU_SVA_GPASID_VAL) {
>  			svm->gpasid = data->gpasid;
>  			svm->flags |= SVM_FLAG_GUEST_PASID;
> +			ioasid_attach_spid(data->hpasid, data->gpasid);
don't you want to handle the returned value?
>  		}
>  		svm->iommu = iommu;
>  		/*
> @@ -517,6 +518,7 @@ int intel_svm_unbind_gpasid(struct device *dev, int pasid)
>  				ioasid_attach_data(pasid, NULL);
>  				ioasid_notify(pasid, IOASID_UNBIND,
>  					IOASID_NOTIFY_SET);
> +				ioasid_attach_spid(pasid, INVALID_IOASID);
So this answers my previous question ;-) but won't it enter the if
(!ioasid_data) path and fail to reset the spid?

Eric
>  				kfree(svm);
>  			}
>  		}
>