This series is to share sva(shared virtual addressing) domains with all
devices bound to one mm.
Problem
-------
In the current iommu core code, sva domain is allocated per IOMMU group,
when device driver is binding a process address space to a device (which is
handled in iommu_sva_bind_device()). If one than more device is bound to
the same process address space, there must be more than one sva domain
instance, with each device having one. In other words, the sva domain
doesn't share between those devices bound to the same process address
space, and that leads to two problems:
1) device driver has to duplicate sva domains with enqcmd, as those sva
domains have the same PASID and are relevant to one virtual address space.
This makes the sva domain handling complex in device drivers.
2) IOMMU driver cannot get sufficient info of the IOMMUs that have
devices behind them bound to the same virtual address space, when handling
mmu_notifier_ops callbacks. As a result, IOMMU IOTLB invalidation is
performed per device instead of per IOMMU, and that may lead to
superfluous IOTLB invalidation issue, especially in a virtualization
environment where all devices may be behind one virtual IOMMU.
Solution
--------
This patch-set tries to fix those two problems by allowing sharing sva
domains with all devices bound to a mm. To achieve this, a new structure
pointer is introduced to mm to replace the old PASID field, which can keep
the info of PASID as well as the corresponding shared sva domains.
Besides, function iommu_sva_bind_device() is updated to ensure a new sva
domain can only be allocated when the old ones cannot work for the IOMMU.
With these changes, a device driver can expect one sva domain could work
for per PASID instance(e.g., enqcmd PASID instance), and therefore may get
rid of handling sva domain duplication. Besides, IOMMU driver (e.g., intel
vt-d driver) can get sufficient info (e.g., the info of the IOMMUs having
their devices bound to one virtual address space) when handling
mmu_notifier_ops callbacks, to remove the redundant IOTLB invalidations.
Arguably there shouldn't be more than one sva_domain with the same PASID,
and in any sane configuration there should be only 1 type of IOMMU driver
that needs only 1 SVA domain. However, in reality, IOMMUs on one platform
may not be identical to each other. Thus, attaching a sva domain that has
been successfully bound to device A behind a IOMMU A, to device B behind
IOMMU B may get failed due to the difference between IOMMU A and IOMMU
B. In this case, a new sva domain with the same PASID needs to be
allocated to work with IOMMU B. That's why we need a list to keep sva
domains of one PASID. For the platform where IOMMUs are compatible to each
other, there should be one sva domain in the list.
v4:
- Rebase to v6.6-rc1.
v3:
- Add a comment describing domain->next.
- Expand explanation of why PASID isn't released in
iommu_sva_unbind_device().
- Add a patch to remove mm->pasid in intel_sva_bind_mm()
v2:
- Add mm_get_enqcmd_pasid().
- Update commit message.
v1: https://lore.kernel.org/linux-iommu/[email protected]/
Tina Zhang (6):
iommu: Add mm_get_enqcmd_pasid() helper function
iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()
iommu: Introduce mm_get_pasid() helper function
mm: Add structure to keep sva information
iommu: Support mm PASID 1:n with sva domains
mm: Deprecate pasid field
arch/x86/kernel/traps.c | 2 +-
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 12 ++---
drivers/iommu/intel/svm.c | 14 +++---
drivers/iommu/iommu-sva.c | 45 ++++++++++++-------
include/linux/iommu.h | 31 ++++++++++---
include/linux/mm_types.h | 3 +-
kernel/fork.c | 1 -
mm/init-mm.c | 3 --
8 files changed, 70 insertions(+), 41 deletions(-)
--
2.34.1
mm_get_enqcmd_pasid() is for getting enqcmd pasid value.
The motivation is to replace mm->pasid with an iommu private data
structure that is introduced in a later patch.
Reviewed-by: Lu Baolu <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
---
Changes in v2:
- Change mm_get_pasid() to mm_get_enqcmd_pasid()
arch/x86/kernel/traps.c | 2 +-
include/linux/iommu.h | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index c876f1d36a81..832f4413d96a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -591,7 +591,7 @@ static bool try_fixup_enqcmd_gp(void)
if (!mm_valid_pasid(current->mm))
return false;
- pasid = current->mm->pasid;
+ pasid = mm_get_enqcmd_pasid(current->mm);
/*
* Did this thread already have its PASID activated?
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index c50a769d569a..a4eab6697fe1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1189,6 +1189,10 @@ static inline bool mm_valid_pasid(struct mm_struct *mm)
{
return mm->pasid != IOMMU_PASID_INVALID;
}
+static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
+{
+ return mm->pasid;
+}
void mm_pasid_drop(struct mm_struct *mm);
struct iommu_sva *iommu_sva_bind_device(struct device *dev,
struct mm_struct *mm);
@@ -1211,6 +1215,10 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
}
static inline void mm_pasid_init(struct mm_struct *mm) {}
static inline bool mm_valid_pasid(struct mm_struct *mm) { return false; }
+static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
+{
+ return IOMMU_PASID_INVALID;
+}
static inline void mm_pasid_drop(struct mm_struct *mm) {}
#endif /* CONFIG_IOMMU_SVA */
--
2.34.1
Introduce iommu_mm_data structure to keep sva information (pasid and the
related sva domains). Add iommu_mm pointer, pointing to an instance of
iommu_mm_data structure, to mm.
Reviewed-by: Vasant Hegde <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
---
include/linux/iommu.h | 5 +++++
include/linux/mm_types.h | 2 ++
2 files changed, 7 insertions(+)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index db2510da28c1..b9c9f14a95cc 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -670,6 +670,11 @@ struct iommu_sva {
struct iommu_domain *domain;
};
+struct iommu_mm_data {
+ u32 pasid;
+ struct list_head sva_domains;
+};
+
int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
const struct iommu_ops *ops);
void iommu_fwspec_free(struct device *dev);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 36c5b43999e6..9f4efed85f74 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -670,6 +670,7 @@ struct mm_cid {
#endif
struct kioctx_table;
+struct iommu_mm_data;
struct mm_struct {
struct {
/*
@@ -883,6 +884,7 @@ struct mm_struct {
#ifdef CONFIG_IOMMU_SVA
u32 pasid;
+ struct iommu_mm_data *iommu_mm;
#endif
#ifdef CONFIG_KSM
/*
--
2.34.1
Each mm bound to devices gets a PASID and corresponding sva domains
allocated in iommu_sva_bind_device(), which are referenced by iommu_mm
field of the mm. The PASID is released in __mmdrop(), while a sva domain
is released when no one is using it (the reference count is decremented
in iommu_sva_unbind_device()). However, although sva domains and their
PASID are separate objects such that their own life cycles could be
handled independently, an enqcmd use case may require releasing the
PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it
will be permanently used by the mm and won't be released until the end
of mm) and only allows to drop the PASID after the sva domains are
released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to
increment the mm reference count and mmdrop() is invoked in
iommu_domain_free() to decrement the mm reference count.
Since the required info of PASID and sva domains is kept in struct
iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid
field in mm struct. The sva domain list is protected by iommu_sva_lock.
Besides, this patch removes mm_pasid_init(), as with the introduced
iommu_mm structure, initializing mm pasid in mm_init() is unnecessary.
Reviewed-by: Lu Baolu <[email protected]>
Reviewed-by: Vasant Hegde <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
---
Changes in v4:
- Rebase to v6.6-rc1.
drivers/iommu/iommu-sva.c | 35 +++++++++++++++++++++++------------
include/linux/iommu.h | 14 +++++++-------
kernel/fork.c | 1 -
3 files changed, 30 insertions(+), 20 deletions(-)
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;
}
static inline u32 mm_get_pasid(struct mm_struct *mm)
{
- return mm->pasid;
+ return mm->iommu_mm ? mm->iommu_mm->pasid : IOMMU_PASID_INVALID;
}
static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
{
@@ -1222,7 +1223,6 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
{
return IOMMU_PASID_INVALID;
}
-static inline void mm_pasid_init(struct mm_struct *mm) {}
static inline bool mm_valid_pasid(struct mm_struct *mm) { return false; }
static inline u32 mm_get_pasid(struct mm_struct *mm)
{
diff --git a/kernel/fork.c b/kernel/fork.c
index 3b6d20dfb9a8..985403a7a747 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1277,7 +1277,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm_init_cpumask(mm);
mm_init_aio(mm);
mm_init_owner(mm, p);
- mm_pasid_init(mm);
RCU_INIT_POINTER(mm->exe_file, NULL);
mmu_notifier_subscriptions_init(mm);
init_tlb_flush_pending(mm);
--
2.34.1
On 9/12/23 8:59 PM, Tina Zhang wrote:
> Introduce iommu_mm_data structure to keep sva information (pasid and the
> related sva domains). Add iommu_mm pointer, pointing to an instance of
> iommu_mm_data structure, to mm.
>
> Reviewed-by: Vasant Hegde<[email protected]>
> Signed-off-by: Tina Zhang<[email protected]>
> ---
> include/linux/iommu.h | 5 +++++
> include/linux/mm_types.h | 2 ++
> 2 files changed, 7 insertions(+)
Reviewed-by: Lu Baolu <[email protected]>
Best regards,
baolu
On Tue, Sep 12, 2023 at 08:59:34PM +0800, Tina Zhang wrote:
> Introduce iommu_mm_data structure to keep sva information (pasid and the
> related sva domains). Add iommu_mm pointer, pointing to an instance of
> iommu_mm_data structure, to mm.
>
> Reviewed-by: Vasant Hegde <[email protected]>
> Signed-off-by: Tina Zhang <[email protected]>
> ---
> include/linux/iommu.h | 5 +++++
> include/linux/mm_types.h | 2 ++
> 2 files changed, 7 insertions(+)
This is not a great way to structure the patches
This patch should move the pasid into the struct and do all the
infrastructure to allocate/free the struct.
The next patch should just add the list head to the now existing struct:
> +struct iommu_mm_data {
> + u32 pasid;
> + struct list_head sva_domains;
> +};
The code looks fine though
Jason
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
On 9/22/23 03:04, Jason Gunthorpe wrote:
> On Tue, Sep 12, 2023 at 08:59:34PM +0800, Tina Zhang wrote:
>> Introduce iommu_mm_data structure to keep sva information (pasid and the
>> related sva domains). Add iommu_mm pointer, pointing to an instance of
>> iommu_mm_data structure, to mm.
>>
>> Reviewed-by: Vasant Hegde <[email protected]>
>> Signed-off-by: Tina Zhang <[email protected]>
>> ---
>> include/linux/iommu.h | 5 +++++
>> include/linux/mm_types.h | 2 ++
>> 2 files changed, 7 insertions(+)
>
> This is not a great way to structure the patches
>
> This patch should move the pasid into the struct and do all the
> infrastructure to allocate/free the struct.
>
> The next patch should just add the list head to the now existing struct:
Agree. It would be great if we can put a new filed adding and its
related handing logic into one patch. It will be convenient not only for
the author but also for the reviewers, as it can convey the intention of
the code change more easily.
In this case, the reason we put new members' introduction into one patch
and their handling logic into another patch, is that it seems an easy
way to replace the old pasid field w/o involving extra temporary logic
to keep everything work between patches. Fortunately, we only have two
new fields, which might make this option not so ugly :)
Regards,
-Tina
>
>> +struct iommu_mm_data {
>> + u32 pasid;
>> + struct list_head sva_domains;
>> +};
>
> The code looks fine though
>
> Jason
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
>