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Message-ID: <20240322165927.GG66976@ziepe.ca>
Date: Fri, 22 Mar 2024 13:59:27 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Baolu Lu <baolu.lu@...ux.intel.com>
Cc: Kevin Tian <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
Nicolin Chen <nicolinc@...dia.com>, Yi Liu <yi.l.liu@...el.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
Joel Granados <j.granados@...sung.com>, iommu@...ts.linux.dev,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/8] iommu/sva: Use iopf domain attach/detach interface
On Thu, Mar 14, 2024 at 03:41:23PM +0800, Baolu Lu wrote:
> The whole cookie mechanism aims to address two things:
>
> - Extend the domain lifetime until all pending page faults are
> resolved.
Like you answered, I think the flush is a simpler scheme..
> - Associate information about the iommu device with each attachment of
> the domain so that the iommufd device object ID could be quickly
> retrieved in the fault delivering path.
> > I see we also need to stick a pointer in the domain for iommufd to get
> > back to the hwpt, but that doesn't seem to need such a big system to
> > accomplish - just add a void *. It would make sense for the domain to
> > have some optional pointer to a struct for all the fault related data
> > that becomes allocated when a PRI domain is created..
>
> It's not getting back hwpt from domain, just getting the iommufd_device
> in the fault delivering path. The iommufd_device is not per-domain, but
> per-domain-attachment.
It does make sense you'd need that, but I think something like this is
a more direct way to get it. Caller allocates the handle struct. The
iopf will provide the handle from the XA to the
callback. container_of() not void * is used to in the caller's API.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 68e648b5576706..0d29d8f0847cd9 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -46,6 +46,8 @@ static unsigned int iommu_def_domain_type __read_mostly;
static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
static u32 iommu_cmd_line __read_mostly;
+enum { IOMMU_PASID_ARRAY_DOMAIN, IOMMU_PASID_ARRAY_HANDLE };
+
struct iommu_group {
struct kobject kobj;
struct kobject *devices_kobj;
@@ -3516,18 +3518,20 @@ static void __iommu_remove_group_pasid(struct iommu_group *group,
}
/*
- * iommu_attach_device_pasid() - Attach a domain to pasid of device
+ * __iommu_attach_device_pasid() - Attach a domain to pasid of device
* @domain: the iommu domain.
* @dev: the attached device.
* @pasid: the pasid of the device.
*
* Return: 0 on success, or an error.
*/
-int iommu_attach_device_pasid(struct iommu_domain *domain,
- struct device *dev, ioasid_t pasid)
+int __iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
+ ioasid_t pasid,
+ struct iommu_pasid_handle *handle)
{
/* Caller must be a probed driver on dev */
struct iommu_group *group = dev->iommu_group;
+ void *xa_entry;
void *curr;
int ret;
@@ -3541,9 +3545,14 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
return -EINVAL;
mutex_lock(&group->mutex);
- curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL);
+ if (handle)
+ xa_entry = xa_tag_pointer(handle, IOMMU_PASID_ARRAY_HANDLE);
+ else
+ xa_entry = xa_tag_pointer(domain, IOMMU_PASID_ARRAY_DOMAIN);
+ curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, xa_entry,
+ GFP_KERNEL);
if (curr) {
- ret = xa_err(curr) ? : -EBUSY;
+ ret = xa_err(curr) ?: -EBUSY;
goto out_unlock;
}
@@ -3556,7 +3565,7 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
mutex_unlock(&group->mutex);
return ret;
}
-EXPORT_SYMBOL_GPL(iommu_attach_device_pasid);
+EXPORT_SYMBOL_GPL(__iommu_attach_device_pasid);
/*
* iommu_detach_device_pasid() - Detach the domain from pasid of device
@@ -3600,13 +3609,23 @@ struct iommu_domain *iommu_get_domain_for_dev_pasid(struct device *dev,
{
/* Caller must be a probed driver on dev */
struct iommu_group *group = dev->iommu_group;
+ struct iommu_pasid_handle *handle;
struct iommu_domain *domain;
+ void *xa_entry;
if (!group)
return NULL;
xa_lock(&group->pasid_array);
- domain = xa_load(&group->pasid_array, pasid);
+ xa_entry = xa_load(&group->pasid_array, pasid);
+ if (xa_pointer_tag(xa_entry) == IOMMU_PASID_ARRAY_HANDLE) {
+ handle = xa_untag_pointer(xa_entry);
+ domain = handle->domain;
+ } else if (xa_pointer_tag(xa_entry) == IOMMU_PASID_ARRAY_DOMAIN) {
+ domain = xa_untag_pointer(xa_entry);
+ } else {
+ domain = NULL;
+ }
if (type && domain && domain->type != type)
domain = ERR_PTR(-EBUSY);
xa_unlock(&group->pasid_array);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 1ea2a820e1eb03..47c121d4e13f65 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -947,8 +947,27 @@ void iommu_device_release_dma_owner(struct device *dev);
struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
struct mm_struct *mm);
-int iommu_attach_device_pasid(struct iommu_domain *domain,
- struct device *dev, ioasid_t pasid);
+
+struct iommu_pasid_handle {
+ struct iommu_domain *domain;
+};
+
+int __iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
+ ioasid_t pasid,
+ struct iommu_pasid_handle *handle);
+
+static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
+ struct device *dev, ioasid_t pasid)
+{
+ return __iommu_attach_device_pasid(domain, dev, pasid, NULL);
+}
+static inline int
+iommu_attach_device_pasid_handle(struct iommu_pasid_handle *handle,
+ struct device *dev, ioasid_t pasid)
+{
+ return __iommu_attach_device_pasid(handle->domain, dev, pasid, handle);
+}
+
void iommu_detach_device_pasid(struct iommu_domain *domain,
struct device *dev, ioasid_t pasid);
struct iommu_domain *
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