From: Tina Zhang <tina.zhang@intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kevin Tian <kevin.tian@intel.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
Michael Shavit <mshavit@google.com>,
Vasant Hegde <vasant.hegde@amd.com>, <iommu@lists.linux.dev>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 5/6] iommu: Support mm PASID 1:n with sva domains
Date: Fri, 22 Sep 2023 09:07:28 +0800 [thread overview]
Message-ID: <40c82e24-cff3-1f96-b469-fbfd18238d5d@intel.com> (raw)
In-Reply-To: <20230921233133.GB13795@ziepe.ca>
Hi Jason,
On 9/22/23 07:31, Jason Gunthorpe wrote:
> On Tue, Sep 12, 2023 at 08:59:35PM +0800, Tina Zhang wrote:
>> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
>> index 0f956ecd0c9b..79779bbef653 100644
>> --- a/drivers/iommu/iommu-sva.c
>> +++ b/drivers/iommu/iommu-sva.c
>> @@ -15,6 +15,7 @@ static DEFINE_MUTEX(iommu_sva_lock);
>> static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
>> {
>> ioasid_t pasid;
>> + struct iommu_mm_data *iommu_mm;
>> int ret = 0;
>>
>> if (!arch_pgtable_dma_compat(mm))
>> @@ -28,12 +29,22 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
>> goto out;
>> }
>>
>> + iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
>> + if (!iommu_mm) {
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> +
>> pasid = iommu_alloc_global_pasid(dev);
>> if (pasid == IOMMU_PASID_INVALID) {
>> + kfree(iommu_mm);
>> ret = -ENOSPC;
>> goto out;
>> }
>> - mm->pasid = pasid;
>> + iommu_mm->pasid = pasid;
>> + INIT_LIST_HEAD(&iommu_mm->sva_domains);
>> + mm->iommu_mm = iommu_mm;
>> +
>> ret = 0;
>> out:
>> mutex_unlock(&iommu_sva_lock);
>> @@ -73,16 +84,12 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
>>
>> mutex_lock(&iommu_sva_lock);
>> /* Search for an existing domain. */
>> - domain = iommu_get_domain_for_dev_pasid(dev, mm_get_pasid(mm),
>> - IOMMU_DOMAIN_SVA);
>> - if (IS_ERR(domain)) {
>> - ret = PTR_ERR(domain);
>> - goto out_unlock;
>> - }
>> -
>> - if (domain) {
>> - domain->users++;
>> - goto out;
>> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
>> + ret = iommu_attach_device_pasid(domain, dev, mm_get_pasid(mm));
>> + if (!ret) {
>> + domain->users++;
>> + goto out;
>> + }
>> }
>>
>> /* Allocate a new domain and set it on device pasid. */
>> @@ -96,6 +103,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
>> if (ret)
>> goto out_free_domain;
>> domain->users = 1;
>> + list_add(&domain->next, &mm->iommu_mm->sva_domains);
>> +
>> out:
>> mutex_unlock(&iommu_sva_lock);
>> handle->dev = dev;
>> @@ -128,8 +137,9 @@ void iommu_sva_unbind_device(struct iommu_sva *handle)
>> struct device *dev = handle->dev;
>>
>> mutex_lock(&iommu_sva_lock);
>> + iommu_detach_device_pasid(domain, dev, pasid);
>> if (--domain->users == 0) {
>> - iommu_detach_device_pasid(domain, dev, pasid);
>> + list_del(&domain->next);
>> iommu_domain_free(domain);
>> }
>> mutex_unlock(&iommu_sva_lock);
>> @@ -209,4 +219,5 @@ void mm_pasid_drop(struct mm_struct *mm)
>> return;
>>
>> iommu_free_global_pasid(mm_get_pasid(mm));
>> + kfree(mm->iommu_mm);
>> }
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index b9c9f14a95cc..c61bc45d5a82 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -109,6 +109,11 @@ struct iommu_domain {
>> struct { /* IOMMU_DOMAIN_SVA */
>> struct mm_struct *mm;
>> int users;
>> + /*
>> + * Next iommu_domain in mm->iommu_mm->sva-domains list
>> + * protected by iommu_sva_lock.
>> + */
>> + struct list_head next;
>> };
>> };
>> };
>> @@ -1186,17 +1191,13 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream
>> }
>>
>> #ifdef CONFIG_IOMMU_SVA
>> -static inline void mm_pasid_init(struct mm_struct *mm)
>> -{
>> - mm->pasid = IOMMU_PASID_INVALID;
>> -}
>> static inline bool mm_valid_pasid(struct mm_struct *mm)
>> {
>> - return mm->pasid != IOMMU_PASID_INVALID;
>> + return mm->iommu_mm ? true : false;
>> }
>
> HUm this isn't locked very nicely.
>
> Above do
>
> smp_store_release(&mm->iommu_mm, iommu_mm);
>
> And then do
>
> return READ_ONCE(mm->iommu_mm)
Good suggestion. Thanks.
>
> (no need for ternaries with bools, compiler generates it automatically)
>
>
>> static inline u32 mm_get_pasid(struct mm_struct *mm)
>> {
>> - return mm->pasid;
>> + return mm->iommu_mm ? mm->iommu_mm->pasid : IOMMU_PASID_INVALID;
>> }
>
> Then this should be
>
> struct iommu_mm_data *iommu_mm = READ_ONCE(mm->iommu_mm);
>
> if (!iommu_mm)
> return IOMMU_PASID_INVALID;
> return iommu_mm->pasid;
>
> Keeping in mind that the kfree(mm->iommu_mm) being placed in the
> mm_drop is critical to this working safely.
Right. Thanks.
Regards,
-Tina
>
> Otherwise the logic looks OK.
>
> Jason
>
next prev parent reply other threads:[~2023-09-22 1:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-12 12:59 [PATCH v4 0/6] Share sva domains with all devices bound to a mm Tina Zhang
2023-09-12 12:59 ` [PATCH v4 1/6] iommu: Add mm_get_enqcmd_pasid() helper function Tina Zhang
2023-09-12 12:59 ` [PATCH v4 2/6] iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm() Tina Zhang
2023-09-13 2:25 ` Baolu Lu
2023-09-21 18:56 ` Jason Gunthorpe
2023-09-22 2:09 ` Tina Zhang
2023-09-12 12:59 ` [PATCH v4 3/6] iommu: Introduce mm_get_pasid() helper function Tina Zhang
2023-09-21 19:02 ` Jason Gunthorpe
2023-09-22 2:07 ` Tina Zhang
2023-09-12 12:59 ` [PATCH v4 4/6] mm: Add structure to keep sva information Tina Zhang
2023-09-13 2:38 ` Baolu Lu
2023-09-21 19:04 ` Jason Gunthorpe
2023-09-22 1:51 ` Tina Zhang
2023-09-12 12:59 ` [PATCH v4 5/6] iommu: Support mm PASID 1:n with sva domains Tina Zhang
2023-09-21 23:31 ` Jason Gunthorpe
2023-09-22 1:07 ` Tina Zhang [this message]
2023-09-12 12:59 ` [PATCH v4 6/6] mm: Deprecate pasid field Tina Zhang
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