From: Jason Gunthorpe <jgg@ziepe.ca>
To: Tina Zhang <tina.zhang@intel.com>
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: Thu, 21 Sep 2023 20:31:33 -0300 [thread overview]
Message-ID: <20230921233133.GB13795@ziepe.ca> (raw)
In-Reply-To: <20230912125936.722348-6-tina.zhang@intel.com>
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)
(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.
Otherwise the logic looks OK.
Jason
next prev parent reply other threads:[~2023-09-21 23:31 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 [this message]
2023-09-22 1:07 ` Tina Zhang
2023-09-12 12:59 ` [PATCH v4 6/6] mm: Deprecate pasid field Tina Zhang
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