From: Vasant Hegde <vasant.hegde@amd.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Tina Zhang <tina.zhang@intel.com>,
Kevin Tian <kevin.tian@intel.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
Michael Shavit <mshavit@google.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/5] iommu: Support mm PASID 1:n with sva domains
Date: Thu, 31 Aug 2023 12:12:58 +0530 [thread overview]
Message-ID: <20b44fe8-33ba-d6ae-110e-a82a19390bcc@amd.com> (raw)
In-Reply-To: <ZO+oRPOf9jyNG2+B@ziepe.ca>
On 8/31/2023 2:06 AM, Jason Gunthorpe wrote:
> On Mon, Aug 28, 2023 at 02:02:52PM +0530, Vasant Hegde wrote:
>
>> I am not sure whether I understood the flow completely. Just wondering why you
>> are not freeing pasid in iommu_sva_unbind_device().
>> I mean once iommu_mm->sva_domains becomes free shouldn't we free the
>> iommu_mm->pasid?
>
> No, for Intel use cases that PASID permanently becomes part of the
> ENQCMD MSR and cannot be revoked once it has been set
>
Fair enough.
Patch description did explain it to some extent. ("The PASID is released in
__mmdrop()"). May be this needs to be expanded to cover why pasid is not
released in iommu_sva_unbind_device().
>> Also in this function (mm_pasid_drop()), should we check/free sva domains?
>
> No, the driver must support a SVA domain with an empty mm_struct, eg
> by hooking release.
Sorry. Looks like confused you. Looking into code I got this.
My question was: when PASID is enabled, is there any chance of mm_pasid_drop()
getting called before freeing all SVA domains?
-Vasant
next prev parent reply other threads:[~2023-08-31 6:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-27 8:43 [PATCH v2 0/5] Share sva domains with all devices bound to a mm Tina Zhang
2023-08-27 8:43 ` [PATCH v2 1/5] iommu: Add mm_get_enqcmd_pasid() helper function Tina Zhang
2023-08-31 2:06 ` Baolu Lu
2023-09-01 2:36 ` Zhang, Tina
2023-08-27 8:43 ` [PATCH v2 2/5] iommu: Introduce mm_get_pasid() " Tina Zhang
2023-08-31 2:24 ` Baolu Lu
2023-08-31 17:01 ` Jason Gunthorpe
2023-08-31 5:14 ` Baolu Lu
2023-08-31 17:02 ` Jason Gunthorpe
2023-09-01 3:29 ` Zhang, Tina
2023-08-27 8:43 ` [PATCH v2 3/5] mm: Add structure to keep sva information Tina Zhang
2023-08-31 2:45 ` Baolu Lu
2023-09-01 3:36 ` Zhang, Tina
2023-09-01 3:49 ` Baolu Lu
2023-08-27 8:44 ` [PATCH v2 4/5] iommu: Support mm PASID 1:n with sva domains Tina Zhang
2023-08-28 8:32 ` Vasant Hegde
2023-08-28 9:10 ` Zhang, Tina
2023-08-31 6:32 ` Vasant Hegde
2023-08-30 20:36 ` Jason Gunthorpe
2023-08-31 6:42 ` Vasant Hegde [this message]
2023-08-31 7:35 ` Baolu Lu
2023-08-31 16:56 ` Jason Gunthorpe
2023-08-31 7:21 ` Baolu Lu
2023-08-27 8:44 ` [PATCH v2 5/5] mm: Deprecate pasid field Tina Zhang
2023-08-29 14:18 ` Niklas Schnelle
2023-08-31 7:39 ` Baolu Lu
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