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SubjectRe: [PATCH v2 9/9] iommu/vt-d: Store guest PASID during bind
On Tue, 1 Sep 2020 19:08:44 +0200
Auger Eric <eric.auger@redhat.com> wrote:

> 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@linux.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?
Yes, I also need to add a check for duplicated SPID within a set.

> > }
> > 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?
>
Sorry, i am not following. If there is no ioasid_data then there is no
SPID to be stored.

BTW, I plan to separate the APIs into two.
ioasid_attach_spid
ioasid_detach_spid

Only ioasid_detach_spid will be calling synchronize RCU, then
ioasid_attach_spid can be called under spinlock.

Thanks,

> Eric
> > kfree(svm);
> > }
> > }
> >
>
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

[Jacob Pan]

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