lkml.org 
[lkml]   [2022]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 6/7] iommu: Use right way to retrieve iommu_ops
    From
    Date
    On 1/25/22 1:36 AM, Jason Gunthorpe wrote:
    > On Mon, Jan 24, 2022 at 03:11:01PM +0800, Lu Baolu wrote:
    >> The common iommu_ops is hooked to both device and domain. When a helper
    >> has both device and domain pointer, the way to get the iommu_ops looks
    >> messy in iommu core. This sorts out the way to get iommu_ops. The device
    >> related helpers go through device pointer, while the domain related ones
    >> go through domain pointer.
    >>
    >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    >> include/linux/iommu.h | 8 ++++++++
    >> drivers/iommu/iommu.c | 25 ++++++++++++++-----------
    >> 2 files changed, 22 insertions(+), 11 deletions(-)
    >>
    >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
    >> index aa5486243892..111b3e9c79bb 100644
    >> +++ b/include/linux/iommu.h
    >> @@ -385,6 +385,14 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
    >> };
    >> }
    >>
    >> +static inline const struct iommu_ops *dev_iommu_ops_get(struct device *dev)
    >> +{
    >> + if (dev && dev->iommu && dev->iommu->iommu_dev)
    >> + return dev->iommu->iommu_dev->ops;
    >> +
    >> + return NULL;
    >
    > What is the purpose of this helper?

    Get the iommu_ops from a device pointer. Just want to avoid duplicate
    code in various functions.

    >
    >> + const struct iommu_ops *ops = dev_iommu_ops_get(dev);
    >> struct iommu_domain *domain = group->default_domain;
    >> struct iommu_resv_region *entry;
    >> struct list_head mappings;
    >> @@ -785,8 +786,8 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
    >> dma_addr_t start, end, addr;
    >> size_t map_size = 0;
    >>
    >> - if (domain->ops->apply_resv_region)
    >> - domain->ops->apply_resv_region(dev, domain, entry);
    >> + if (ops->apply_resv_region)
    >> + ops->apply_resv_region(dev, domain, entry);
    >
    > Here we call it and don't check for NULL? So why did we check the
    > interior pointers in the helper?

    Yes. Should check.

    >
    >> @@ -831,8 +832,10 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
    >> static bool iommu_is_attach_deferred(struct iommu_domain *domain,
    >> struct device *dev)
    >> {
    >> - if (domain->ops->is_attach_deferred)
    >> - return domain->ops->is_attach_deferred(domain, dev);
    >> + const struct iommu_ops *ops = dev_iommu_ops_get(dev);
    >> +
    >> + if (ops->is_attach_deferred)
    >> + return ops->is_attach_deferred(domain, dev);
    >
    > Same here, at least return false if ops is null..

    Yes.

    >
    >> @@ -1251,10 +1254,10 @@ int iommu_page_response(struct device *dev,
    >> struct iommu_fault_event *evt;
    >> struct iommu_fault_page_request *prm;
    >> struct dev_iommu *param = dev->iommu;
    >> + const struct iommu_ops *ops = dev_iommu_ops_get(dev);
    >> bool has_pasid = msg->flags & IOMMU_PAGE_RESP_PASID_VALID;
    >> - struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
    >>
    >> - if (!domain || !domain->ops->page_response)
    >> + if (!ops || !ops->page_response)
    >> return -ENODEV;
    >>
    >> if (!param || !param->fault_param)
    >> @@ -1295,7 +1298,7 @@ int iommu_page_response(struct device *dev,
    >> msg->pasid = 0;
    >> }
    >>
    >> - ret = domain->ops->page_response(dev, evt, msg);
    >> + ret = ops->page_response(dev, evt, msg);
    >> list_del(&evt->list);
    >> kfree(evt);
    >> break;
    >
    > Feels weird that page_response is not connected to a domain, the fault
    > originated from a domain after all. I would say this op should be
    > moved to the domain and the caller should provide the a pointer to the
    > domain that originated the fault.
    >
    > Ideally since only some domain's will be configured to handle faults
    > at all - domains that can't do this should have a NULL page_response
    > op, even if other domains created by the same device driver could
    > handle page_response..
    >
    >> @@ -1758,10 +1761,10 @@ static int __iommu_group_dma_attach(struct iommu_group *group)
    >>
    >> static int iommu_group_do_probe_finalize(struct device *dev, void *data)
    >> {
    >> - struct iommu_domain *domain = data;
    >> + const struct iommu_ops *ops = dev_iommu_ops_get(dev);
    >>
    >> - if (domain->ops->probe_finalize)
    >> - domain->ops->probe_finalize(dev);
    >> + if (ops->probe_finalize)
    >> + ops->probe_finalize(dev);
    >
    > This is an oddball one too, it is finishing setting up the default
    > domain for a device? Several drivers seem to recover the default
    > domain in their implementations..

    In order to avoid default domain type (DMA or IDENDITY) conflict among
    devices in a same iommu_group, the probe process is divided into two
    phases, one for determining the default domain type and the other for
    allocating the default domain and attaching it to the device.

    ops->probe_finalize() is called to tell the vendor iommu driver that
    the device probe is done. Normally the vendor iommu driver could set the
    dma ops in this callback.

    >
    > Jason
    >

    Best regards,
    baolu

    \
     
     \ /
      Last update: 2022-01-25 05:51    [W:4.080 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site