Re: [PATCH 5/9] iommu: Make fault_param generic

[Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>]

On 2023/7/12 5:31, Jacob Pan wrote:
> On Tue, 11 Jul 2023 09:06:38 +0800, Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
> wrote:
>
> > The iommu faults, including recoverable faults (IO page faults) and
> > unrecoverable faults (DMA faults), are generic to all devices. The
> > iommu faults could possibly be triggered for every device.
> >
> > The fault_param pointer under struct dev_iommu is the per-device fault
> > data. Therefore, the fault_param pointer should be allocated during
> > iommu device probe and freed when the device is released.
> >
> > With this done, the individual iommu drivers that support iopf have no
> > need to call iommu_[un]register_device_fault_handler() any more.
> > This will make it easier for the iommu drivers to support iopf, and it
> > will also make the fault_param allocation and free simpler.
> >
> > Signed-off-by: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
> > ---
> >   .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c    | 13 +------------
> >   drivers/iommu/intel/iommu.c                    | 18 ++++--------------
> >   drivers/iommu/iommu.c                          | 14 ++++++++++++++
> >   3 files changed, 19 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c index
> > a5a63b1c947e..fa8ab9d413f8 100644 ---
> > a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c +++
> > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c @@ -437,7 +437,6 @@
> > bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
> >   static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master
> > *master) {
> > -	int ret;
> >   	struct device *dev = master->dev;
> >   
> >   	/*
> > @@ -450,16 +449,7 @@ static int arm_smmu_master_sva_enable_iopf(struct
> > arm_smmu_master *master) if (!master->iopf_enabled)
> >   		return -EINVAL;
> >   
> > -	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
> > -	if (ret)
> > -		return ret;
> > -
> > -	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf,
> > dev);
> > -	if (ret) {
> > -		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> > -		return ret;
> > -	}
> > -	return 0;
> > +	return iopf_queue_add_device(master->smmu->evtq.iopf, dev);
> >   }
> >   
> >   static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master
> > *master) @@ -469,7 +459,6 @@ static void
> > arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master) if
> > (!master->iopf_enabled) return;
> >   
> > -	iommu_unregister_device_fault_handler(dev);
> >   	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> >   }
> >   
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 5c8c5cdc36cf..22e43db20252 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -4594,23 +4594,14 @@ static int intel_iommu_enable_iopf(struct device
> > *dev) if (ret)
> >   		return ret;
> >   
> > -	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf,
> > dev);
> > -	if (ret)
> > -		goto iopf_remove_device;
> > -
> >   	ret = pci_enable_pri(pdev, PRQ_DEPTH);
> > -	if (ret)
> > -		goto iopf_unregister_handler;
> > +	if (ret) {
> > +		iopf_queue_remove_device(iommu->iopf_queue, dev);
> > +		return ret;
> > +	}
> >   	info->pri_enabled = 1;
> >   
> >   	return 0;
> > -
> > -iopf_unregister_handler:
> > -	iommu_unregister_device_fault_handler(dev);
> > -iopf_remove_device:
> > -	iopf_queue_remove_device(iommu->iopf_queue, dev);
> > -
> > -	return ret;
> >   }
> >   
> >   static int intel_iommu_disable_iopf(struct device *dev)
> > @@ -4637,7 +4628,6 @@ static int intel_iommu_disable_iopf(struct device
> > *dev)
> >   	 * fault handler and removing device from iopf queue should never
> >   	 * fail.
> >   	 */
> > -	WARN_ON(iommu_unregister_device_fault_handler(dev));
> >   	WARN_ON(iopf_queue_remove_device(iommu->iopf_queue, dev));
> >   
> >   	return 0;
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 65895b987e22..8d1f0935ea71 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -299,7 +299,15 @@ static int dev_iommu_get(struct device *dev)
> >   		return -ENOMEM;
> >   
> >   	mutex_init(&param->lock);
> > +	param->fault_param = kzalloc(sizeof(*param->fault_param),
> > GFP_KERNEL);
> since fault_param is_always_  allocated/freed along with param, can we merge
> into one allocation? i.e.
>   struct dev_iommu {
>          struct mutex lock;
> -       struct iommu_fault_param        *fault_param;
> +       struct iommu_fault_param        fault_param;

I am not pretty sure about the change in this patch. It's a simple-and-
stupid way. But it also wastes memory for devices that have not pri-
capable domain attached.

So probably it's better to allocate fault_param at the place where a
real pri-capable domain is attached to the device?

Best regards,
baolu