From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Joerg Roedel <joro@8bytes.org>,
"David Woodhouse" <dwmw2@infradead.org>,
Alex Williamson <alex.williamson@redhat.com>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
Christoph Hellwig <hch@infradead.org>,
"Jonathan Cameron" <jic23@kernel.org>,
Eric Auger <eric.auger@redhat.com>,
jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID
Date: Mon, 28 Oct 2019 15:49:00 -0700 [thread overview]
Message-ID: <20191028154900.0be0a48f@jacob-builder> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D5D0FF0@SHSMSX104.ccr.corp.intel.com>
On Fri, 25 Oct 2019 15:52:39 +0000
"Tian, Kevin" <kevin.tian@intel.com> wrote:
> > From: Lu Baolu [mailto:baolu.lu@linux.intel.com]
> > Sent: Friday, October 25, 2019 10:39 PM
> >
> > Hi,
> >
> > On 10/25/19 2:40 PM, Tian, Kevin wrote:
> > >>>> ioasid_register_allocator(&iommu->pasid_allocator);
> > >>>> + if (ret) {
> > >>>> + pr_warn("Custom PASID
> > >>>> allocator registeration failed\n");
> > >>>> + /*
> > >>>> + * Disable scalable mode on
> > >>>> this IOMMU if there
> > >>>> + * is no custom allocator.
> > >>>> Mixing SM capable vIOMMU
> > >>>> + * and non-SM vIOMMU are not
> > >>>> supported.
> > >>>> + */
> > >>>> + intel_iommu_sm = 0;
> > >>> It's insufficient to disable scalable mode by only clearing
> > >>> intel_iommu_sm. The DMA_RTADDR_SMT bit in root entry has
> > >>> already
> > >> been
> > >>> set. Probably, you need to
> > >>>
> > >>> for each iommu
> > >>> clear DMA_RTADDR_SMT in root entry
> > >>>
> > >>> Alternatively, since vSVA is the only customer of this custom
> > >>> PASID allocator, is it possible to only disable SVA here?
> > >>>
> > >> Yeah, I think disable SVA is better. We can still do gIOVA in
> > >> SM. I guess we need to introduce a flag for sva_enabled.
> > > I'm not sure whether tying above logic to SVA is the right
> > > approach. If vcmd interface doesn't work, the whole SM mode
> > > doesn't make sense which is based on PASID-granular protection
> > > (SVA is only one usage atop). If the only remaining usage of SM
> > > is to map gIOVA using reserved PASID#0, then why not disabling SM
> > > and just fallback to legacy mode?
> > >
> > > Based on that I prefer to disabling the SM mode completely (better
> > > through an interface), and move the logic out of CONFIG_INTEL_
> > > IOMMU_SVM
> > >
> >
> > Unfortunately, it is dangerous to disable SM after boot. SM uses
> > different root/device contexts and pasid table formats. Disabling SM
> > after boot requires changing above from SM format into legacy
> > format.
>
> You are correct.
>
> >
> > Since ioasid registration failure is a rare case. How about moving
> > this part of code up to the early stage of intel_iommu_init() and
> > returning error if hardware present vcmd capability but software
> > fails to register a custom ioasid allocator?
> >
>
> It makes sense to me.
>
sounds good to me too, the earlier the less to clean up.
> Thanks
> Kevin
[Jacob Pan]
next prev parent reply other threads:[~2019-10-28 22:44 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-24 19:54 [PATCH v7 00/11] Nested Shared Virtual Address (SVA) VT-d support Jacob Pan
2019-10-24 19:54 ` [PATCH v7 01/11] iommu/vt-d: Cache virtual command capability register Jacob Pan
2019-10-25 2:53 ` Lu Baolu
2019-10-25 6:06 ` Tian, Kevin
2019-11-08 10:32 ` Auger Eric
2019-10-24 19:54 ` [PATCH v7 02/11] iommu/vt-d: Enlightened PASID allocation Jacob Pan
2019-10-25 6:19 ` Tian, Kevin
2019-10-29 17:14 ` Jacob Pan
2019-10-29 18:16 ` Tian, Kevin
2019-11-08 10:33 ` Auger Eric
2019-11-08 22:22 ` Jacob Pan
2019-10-24 19:54 ` [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID Jacob Pan
2019-10-25 2:30 ` Lu Baolu
2019-10-25 4:43 ` Jacob Pan
2019-10-25 6:40 ` Tian, Kevin
2019-10-25 14:39 ` Lu Baolu
2019-10-25 15:52 ` Tian, Kevin
2019-10-28 22:49 ` Jacob Pan [this message]
2019-10-29 2:22 ` Lu Baolu
2019-10-25 6:31 ` Tian, Kevin
2019-10-28 22:52 ` Jacob Pan
2019-11-08 10:40 ` Auger Eric
2019-11-08 22:26 ` Jacob Pan
2019-10-24 19:54 ` [PATCH v7 04/11] iommu/vt-d: Replace Intel specific PASID allocator with IOASID Jacob Pan
2019-10-25 5:47 ` Lu Baolu
2019-11-01 18:29 ` Jacob Pan
2019-10-25 6:41 ` Tian, Kevin
2019-10-28 22:46 ` Jacob Pan
2019-11-08 11:30 ` Auger Eric
2019-11-08 22:55 ` Jacob Pan
2019-11-12 9:54 ` Auger Eric
2019-10-24 19:54 ` [PATCH v7 05/11] iommu/vt-d: Move domain helper to header Jacob Pan
2019-10-25 5:26 ` Lu Baolu
2019-10-24 19:54 ` [PATCH v7 06/11] iommu/vt-d: Avoid duplicated code for PASID setup Jacob Pan
2019-10-25 5:32 ` Lu Baolu
2019-10-25 6:42 ` Tian, Kevin
2019-10-28 22:41 ` Jacob Pan
2019-11-12 9:54 ` Auger Eric
2019-10-24 19:55 ` [PATCH v7 07/11] iommu/vt-d: Add nested translation helper function Jacob Pan
2019-10-25 7:04 ` Tian, Kevin
2019-11-01 21:10 ` Jacob Pan
2019-10-25 15:04 ` Lu Baolu
2019-10-25 16:06 ` Jacob Pan
2019-11-08 13:55 ` Auger Eric
2019-10-24 19:55 ` [PATCH v7 08/11] iommu/vt-d: Misc macro clean up for SVM Jacob Pan
2019-10-26 1:00 ` Lu Baolu
2019-10-28 22:38 ` Jacob Pan
2019-10-24 19:55 ` [PATCH v7 09/11] iommu/vt-d: Add bind guest PASID support Jacob Pan
2019-10-25 7:19 ` Tian, Kevin
2019-10-25 17:33 ` Jacob Pan
2019-10-28 6:03 ` Tian, Kevin
2019-10-28 16:02 ` Jacob Pan
2019-10-29 7:57 ` Tian, Kevin
2019-10-29 16:11 ` Jacob Pan
2019-10-29 18:04 ` Tian, Kevin
2019-10-29 2:33 ` Lu Baolu
2019-10-26 2:01 ` Lu Baolu
2019-10-28 22:29 ` Jacob Pan
2019-10-29 2:54 ` Lu Baolu
2019-10-29 4:11 ` Jacob Pan
2019-10-29 5:04 ` Lu Baolu
2019-10-24 19:55 ` [PATCH v7 10/11] iommu/vt-d: Support flushing more translation cache types Jacob Pan
2019-10-25 7:21 ` Tian, Kevin
2019-11-01 21:30 ` Jacob Pan
2019-10-26 2:22 ` Lu Baolu
2019-11-01 21:28 ` Jacob Pan
2019-11-08 16:18 ` Auger Eric
2019-11-08 23:05 ` Jacob Pan
2019-10-24 19:55 ` [PATCH v7 11/11] iommu/vt-d: Add svm/sva invalidate function Jacob Pan
2019-10-25 7:27 ` Tian, Kevin
2019-10-26 2:40 ` Lu Baolu
2019-10-26 7:03 ` Lu Baolu
2019-10-28 6:06 ` Tian, Kevin
2019-10-28 16:10 ` Jacob Pan
2019-10-29 18:52 ` Tian, Kevin
2019-10-29 19:25 ` Jacob Pan
2019-10-28 16:13 ` Jacob Pan
2019-11-12 10:28 ` Auger Eric
2020-02-15 1:18 ` Jacob Pan
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