From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
"Raj, Ashok" <ashok.raj@intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"Lu, Baolu" <baolu.lu@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>, "Wu, Hao" <hao.wu@intel.com>
Subject: IOASID set token
Date: Wed, 1 Jul 2020 23:29:16 -0700 [thread overview]
Message-ID: <20200701232916.38fd7908@jacob-builder> (raw)
Hi Jean,
Have a question for you on whether we can have a fixed token type for
ioasid_set.
Currently, ioasid_set has an arbitrary token. For VT-d vSVA usage, we
choose mm as ioasid_set token to identify PASIDs within a guest. We have
multiple in-kernel users of PASIDs such as VFIO, KVM, and VDCM. When an
IOASID set is created, there is not a good way to communicate about the
token choices. So we have to let VDCM and KVM *assume* mm is used as
token, then retrieve ioasid_set based on the token.
This assumption of "mm as token" is not a reliable SW architecture. So
we are thinking if we can have an explicit ioasid_set token type where
mm is used. After all, PASID and mm are closely related.
The code change might be the following:
1. add a flag to indicate token type when ioasid_set is allocated, e.g.
IOASID_SET_TYPE_MM
IOASID_SET_TYPE_ANY
2. other users of the ioasid_set can query if an mm token exists based
on the flag IOASID_SET_TYPE_MM, then retrieve the ioasid_set.
Existing ioasid_set user can still use arbitrary token under the flag
IOASID_SET_TYPE_ANY
Would this be an issue for ARM usage?
Thanks,
Jacob
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next reply other threads:[~2020-07-02 6:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 6:29 Jacob Pan [this message]
2020-07-02 13:48 ` IOASID set token Jacob Pan
2020-07-06 10:30 ` Jean-Philippe Brucker
2020-07-06 20:51 ` Jacob Pan
2020-07-07 10:07 ` Jean-Philippe Brucker
2020-07-07 15:38 ` Jacob Pan
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