From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Will Deacon <Will.Deacon@arm.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
Mark Rutland <Mark.Rutland@arm.com>,
Robin Murphy <Robin.Murphy@arm.com>,
"jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"eric.auger@redhat.com" <eric.auger@redhat.com>
Subject: Re: [PATCH 6/8] iommu/arm-smmu-v3: Support auxiliary domains
Date: Fri, 5 Jul 2019 17:29:06 +0100 [thread overview]
Message-ID: <7cad065e-5eba-bd22-5c1d-c55ad315ace0@arm.com> (raw)
In-Reply-To: <20190626175959.ubxvb2qn4taclact@willie-the-truck>
On 26/06/2019 18:59, Will Deacon wrote:
>> +static void arm_smmu_aux_detach_dev(struct iommu_domain *domain, struct device *dev)
>> +{
>> + struct iommu_domain *parent_domain;
>> + struct arm_smmu_domain *parent_smmu_domain;
>> + struct arm_smmu_master *master = dev_to_master(dev);
>> + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +
>> + if (!arm_smmu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX))
>> + return;
>> +
>> + parent_domain = iommu_get_domain_for_dev(dev);
>> + if (!parent_domain)
>> + return;
>> + parent_smmu_domain = to_smmu_domain(parent_domain);
>> +
>> + mutex_lock(&smmu_domain->init_mutex);
>> + if (!smmu_domain->aux_nr_devs)
>> + goto out_unlock;
>> +
>> + if (!--smmu_domain->aux_nr_devs) {
>> + arm_smmu_write_ctx_desc(parent_smmu_domain, smmu_domain->ssid,
>> + NULL);
>> + /*
>> + * TLB doesn't need invalidation since accesses from the device
>> + * can't use this domain's ASID once the CD is clear.
>> + *
>> + * Sadly that doesn't apply to ATCs, which are PASID tagged.
>> + * Invalidate all other devices as well, because even though
>> + * they weren't 'officially' attached to the auxiliary domain,
>> + * they could have formed ATC entries.
>> + */
>> + arm_smmu_atc_inv_domain(smmu_domain, 0, 0);
>
> I've been struggling to understand the locking here, since both
> arm_smmu_write_ctx_desc and arm_smmu_atc_inv_domain take and release the
> devices_lock for the domain. Is there not a problem with devices coming and
> going in-between the two calls?
Yes it's a problem. I suppose we could take the parent's init_mutex
(making sure that it protects detach_dev() as well.
First I need to figure out how to prevent the parent domain from
disappearing when auxiliary domains are attached, I seem to have forgotten
that. I think checking if AUXD is enabled in the device passed to
attach_dev() should be sufficient - that's what I do for SVA. But the
IOMMU API isn't quite ready to handle failure in iommu_detach_device() at
the moment. VFIO will free the domain even if it's still attached.
>
>> + } else {
>> + struct arm_smmu_cmdq_ent cmd;
>> +
>> + /* Invalidate only this device's ATC */
>> + if (master->ats_enabled) {
>> + arm_smmu_atc_inv_to_cmd(smmu_domain->ssid, 0, 0, &cmd);
>> + arm_smmu_atc_inv_master(master, &cmd);
>> + }
>> + }
>> +out_unlock:
>> + mutex_unlock(&smmu_domain->init_mutex);
>> +}
>> +
>> +static int arm_smmu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
>> +{
>> + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +
>> + return smmu_domain->ssid ?: -EINVAL;
>> +}
>> +
>> static struct iommu_ops arm_smmu_ops = {
>> .capable = arm_smmu_capable,
>> .domain_alloc = arm_smmu_domain_alloc,
>> @@ -2539,6 +2772,13 @@ static struct iommu_ops arm_smmu_ops = {
>> .of_xlate = arm_smmu_of_xlate,
>> .get_resv_regions = arm_smmu_get_resv_regions,
>> .put_resv_regions = arm_smmu_put_resv_regions,
>> + .dev_has_feat = arm_smmu_dev_has_feature,
>> + .dev_feat_enabled = arm_smmu_dev_feature_enabled,
>> + .dev_enable_feat = arm_smmu_dev_enable_feature,
>> + .dev_disable_feat = arm_smmu_dev_disable_feature,
>
> Why can't we use the existing ->capable and ->dev_{get,set}_attr callbacks
> for this?
->capable isn't very useful because it applies to all SMMUs in the
system. The existing ->{get,set}_attr callbacks apply to an
iommu_domain. The main reason for doing it on endpoints was that it
would be tedious to keep track of capabilities when attaching and
detaching devices to a domain, especially for drivers that allow
multiple IOMMUs per domain [1]. There were more discussions, and in the
end Joerg proposed the current API for device attributes [2]
[1]
https://lore.kernel.org/lkml/aa1ff748-c2ec-acc0-f1d9-cdff2b131e58@linux.intel.com/
[2] https://lore.kernel.org/linux-iommu/20181207102926.GM16835@8bytes.org/
Thanks,
Jean
next prev parent reply other threads:[~2019-07-05 16:29 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-10 18:47 [PATCH 0/8] iommu: Add auxiliary domain and PASID support to Arm SMMUv3 Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 1/8] iommu: Add I/O ASID allocator Jean-Philippe Brucker
2019-06-11 9:36 ` Jonathan Cameron
2019-06-11 14:35 ` Jean-Philippe Brucker
2019-06-11 18:13 ` Jacob Pan
2019-06-18 14:22 ` Jean-Philippe Brucker
2019-06-18 17:05 ` Jacob Pan
2019-06-19 14:26 ` Jean-Philippe Brucker
2019-06-11 12:26 ` Jacob Pan
2019-06-11 14:37 ` Jean-Philippe Brucker
2019-06-11 17:10 ` Jacob Pan
2019-06-12 11:30 ` Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 2/8] dt-bindings: document PASID property for IOMMU masters Jean-Philippe Brucker
2019-07-08 7:58 ` Auger Eric
2019-06-10 18:47 ` [PATCH 3/8] iommu/arm-smmu-v3: Support platform SSID Jean-Philippe Brucker
2019-06-11 9:42 ` Jonathan Cameron
2019-06-11 14:35 ` Jean-Philippe Brucker
2019-06-18 18:08 ` Will Deacon
2019-06-19 11:53 ` Jean-Philippe Brucker
2019-07-08 7:58 ` Auger Eric
2019-09-19 14:51 ` Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 4/8] iommu/arm-smmu-v3: Add support for Substream IDs Jean-Philippe Brucker
2019-06-11 10:19 ` Jonathan Cameron
2019-06-11 14:35 ` Jean-Philippe Brucker
2019-06-26 18:00 ` Will Deacon
2019-07-04 9:33 ` Jean-Philippe Brucker
2019-09-19 14:57 ` Jean-Philippe Brucker
2019-07-08 15:31 ` Auger Eric
2019-09-19 15:01 ` Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 5/8] iommu/arm-smmu-v3: Add second level of context descriptor table Jean-Philippe Brucker
2019-06-11 10:24 ` Jonathan Cameron
2019-07-08 15:13 ` Auger Eric
2019-09-19 15:05 ` Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 6/8] iommu/arm-smmu-v3: Support auxiliary domains Jean-Philippe Brucker
2019-06-26 17:59 ` Will Deacon
2019-07-05 16:29 ` Jean-Philippe Brucker [this message]
2019-09-19 15:06 ` Jean-Philippe Brucker
2019-06-10 18:47 ` [PATCH 7/8] iommu/arm-smmu-v3: Improve add_device() error handling Jean-Philippe Brucker
2019-07-08 7:58 ` Auger Eric
2019-06-10 18:47 ` [PATCH 8/8] iommu/arm-smmu-v3: Add support for PCI PASID Jean-Philippe Brucker
2019-06-11 10:45 ` Jonathan Cameron
2019-06-11 14:35 ` Jean-Philippe Brucker
2019-07-08 7:58 ` Auger Eric
2019-09-19 15:10 ` Jean-Philippe Brucker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7cad065e-5eba-bd22-5c1d-c55ad315ace0@arm.com \
--to=jean-philippe.brucker@arm.com \
--cc=Mark.Rutland@arm.com \
--cc=Robin.Murphy@arm.com \
--cc=Will.Deacon@arm.com \
--cc=devicetree@vger.kernel.org \
--cc=eric.auger@redhat.com \
--cc=iommu@lists.linux-foundation.org \
--cc=jacob.jun.pan@linux.intel.com \
--cc=joro@8bytes.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robh+dt@kernel.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).