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Message-ID: <62ccc75d-3f30-4167-b9e1-21dd95a6631d@intel.com>
Date: Sat, 18 Jan 2025 16:23:22 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Nicolin Chen <nicolinc@...dia.com>, <will@...nel.org>,
	<robin.murphy@....com>, <jgg@...dia.com>, <kevin.tian@...el.com>,
	<tglx@...utronix.de>, <maz@...nel.org>, <alex.williamson@...hat.com>
CC: <joro@...tes.org>, <shuah@...nel.org>, <reinette.chatre@...el.com>,
	<eric.auger@...hat.com>, <yebin10@...wei.com>, <apatel@...tanamicro.com>,
	<shivamurthy.shastri@...utronix.de>, <bhelgaas@...gle.com>,
	<anna-maria@...utronix.de>, <yury.norov@...il.com>, <nipun.gupta@....com>,
	<iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>, <patches@...ts.linux.dev>,
	<jean-philippe@...aro.org>, <mdf@...nel.org>, <mshavit@...gle.com>,
	<shameerali.kolothum.thodi@...wei.com>, <smostafa@...gle.com>,
	<ddutile@...hat.com>
Subject: Re: [PATCH RFCv2 06/13] iommufd: Make attach_handle generic

On 2025/1/11 11:32, Nicolin Chen wrote:
> "attach_handle" was added exclusively for the iommufd_fault_iopf_handler()
> used by IOPF/PRI use cases, along with the "fault_data". Now, the iommufd
> version of sw_msi function will resue the attach_handle and fault_data for
> a non-fault case.
> 
> Move the attach_handle part out of the fault.c file to make it generic for
> all cases. Simplify the remaining fault specific routine to attach/detach.

I guess you can send it separately since both of our series need it. :)

> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>   drivers/iommu/iommufd/iommufd_private.h |  40 +-------
>   drivers/iommu/iommufd/device.c          | 105 +++++++++++++++++++++
>   drivers/iommu/iommufd/fault.c           | 120 +++---------------------
>   3 files changed, 122 insertions(+), 143 deletions(-)
> 
> diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
> index b6d706cf2c66..063c0a42f54f 100644
> --- a/drivers/iommu/iommufd/iommufd_private.h
> +++ b/drivers/iommu/iommufd/iommufd_private.h
> @@ -472,42 +472,12 @@ void iommufd_fault_destroy(struct iommufd_object *obj);
>   int iommufd_fault_iopf_handler(struct iopf_group *group);
>   
>   int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
> -				    struct iommufd_device *idev);
> +				    struct iommufd_device *idev,
> +				    bool enable_iopf);
>   void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
> -				     struct iommufd_device *idev);
> -int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
> -				     struct iommufd_hw_pagetable *hwpt,
> -				     struct iommufd_hw_pagetable *old);
> -
> -static inline int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
> -					     struct iommufd_device *idev)
> -{
> -	if (hwpt->fault)
> -		return iommufd_fault_domain_attach_dev(hwpt, idev);
> -
> -	return iommu_attach_group(hwpt->domain, idev->igroup->group);
> -}
> -
> -static inline void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt,
> -					      struct iommufd_device *idev)
> -{
> -	if (hwpt->fault) {
> -		iommufd_fault_domain_detach_dev(hwpt, idev);
> -		return;
> -	}
> -
> -	iommu_detach_group(hwpt->domain, idev->igroup->group);
> -}
> -
> -static inline int iommufd_hwpt_replace_device(struct iommufd_device *idev,
> -					      struct iommufd_hw_pagetable *hwpt,
> -					      struct iommufd_hw_pagetable *old)
> -{
> -	if (old->fault || hwpt->fault)
> -		return iommufd_fault_domain_replace_dev(idev, hwpt, old);
> -
> -	return iommu_group_replace_domain(idev->igroup->group, hwpt->domain);
> -}
> +				     struct iommufd_device *idev,
> +				     struct iommufd_attach_handle *handle,
> +				     bool disable_iopf);
>   
>   static inline struct iommufd_viommu *
>   iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index dfd0898fb6c1..38b31b652147 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -352,6 +352,111 @@ iommufd_device_attach_reserved_iova(struct iommufd_device *idev,
>   	return 0;
>   }
>   
> +/* The device attach/detach/replace helpers for attach_handle */
> +
> +static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
> +				      struct iommufd_device *idev)
> +{
> +	struct iommufd_attach_handle *handle;
> +	int rc;
> +
> +	if (hwpt->fault) {
> +		rc = iommufd_fault_domain_attach_dev(hwpt, idev, true);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> +	if (!handle) {
> +		rc = -ENOMEM;
> +		goto out_fault_detach;
> +	}
> +
> +	handle->idev = idev;
> +	rc = iommu_attach_group_handle(hwpt->domain, idev->igroup->group,
> +				       &handle->handle);
> +	if (rc)
> +		goto out_free_handle;
> +
> +	return 0;
> +
> +out_free_handle:
> +	kfree(handle);
> +	handle = NULL;
> +out_fault_detach:
> +	if (hwpt->fault)
> +		iommufd_fault_domain_detach_dev(hwpt, idev, handle, true);
> +	return rc;
> +}
> +
> +static struct iommufd_attach_handle *
> +iommufd_device_get_attach_handle(struct iommufd_device *idev)
> +{
> +	struct iommu_attach_handle *handle;
> +
> +	handle =
> +		iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
> +	if (IS_ERR(handle))
> +		return NULL;
> +	return to_iommufd_handle(handle);
> +}
> +
> +static void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt,
> +				       struct iommufd_device *idev)
> +{
> +	struct iommufd_attach_handle *handle;
> +
> +	handle = iommufd_device_get_attach_handle(idev);
> +	iommu_detach_group_handle(hwpt->domain, idev->igroup->group);
> +	if (hwpt->fault)
> +		iommufd_fault_domain_detach_dev(hwpt, idev, handle, true);
> +	kfree(handle);
> +}
> +
> +static int iommufd_hwpt_replace_device(struct iommufd_device *idev,
> +				       struct iommufd_hw_pagetable *hwpt,
> +				       struct iommufd_hw_pagetable *old)
> +{
> +	struct iommufd_attach_handle *old_handle =
> +		iommufd_device_get_attach_handle(idev);
> +	struct iommufd_attach_handle *handle;
> +	int rc;
> +
> +	if (hwpt->fault) {
> +		rc = iommufd_fault_domain_attach_dev(hwpt, idev, !old->fault);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> +	if (!handle) {
> +		rc = -ENOMEM;
> +		goto out_fault_detach;
> +	}
> +
> +	handle->idev = idev;
> +	rc = iommu_replace_group_handle(idev->igroup->group, hwpt->domain,
> +					&handle->handle);
> +	if (rc)
> +		goto out_free_handle;
> +
> +	if (old->fault)
> +		iommufd_fault_domain_detach_dev(old, idev, old_handle,
> +						!hwpt->fault);
> +	kfree(old_handle);
> +
> +	return 0;
> +
> +out_free_handle:
> +	kfree(handle);
> +	handle = NULL;
> +out_fault_detach:
> +	if (hwpt->fault)
> +		iommufd_fault_domain_detach_dev(hwpt, idev, handle,
> +						!old->fault);
> +	return rc;
> +}
> +
>   int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
>   				struct iommufd_device *idev)
>   {
> diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
> index 06aa83a75e94..1d9bd3024b57 100644
> --- a/drivers/iommu/iommufd/fault.c
> +++ b/drivers/iommu/iommufd/fault.c
> @@ -60,42 +60,17 @@ static void iommufd_fault_iopf_disable(struct iommufd_device *idev)
>   	mutex_unlock(&idev->iopf_lock);
>   }
>   
> -static int __fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
> -				     struct iommufd_device *idev)
> -{
> -	struct iommufd_attach_handle *handle;
> -	int ret;
> -
> -	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> -	if (!handle)
> -		return -ENOMEM;
> -
> -	handle->idev = idev;
> -	ret = iommu_attach_group_handle(hwpt->domain, idev->igroup->group,
> -					&handle->handle);
> -	if (ret)
> -		kfree(handle);
> -
> -	return ret;
> -}
> -
>   int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
> -				    struct iommufd_device *idev)
> +				    struct iommufd_device *idev,
> +				    bool enable_iopf)
>   {
> -	int ret;
> +	int rc = 0;
>   
>   	if (!hwpt->fault)
>   		return -EINVAL;
> -
> -	ret = iommufd_fault_iopf_enable(idev);
> -	if (ret)
> -		return ret;
> -
> -	ret = __fault_domain_attach_dev(hwpt, idev);
> -	if (ret)
> -		iommufd_fault_iopf_disable(idev);
> -
> -	return ret;
> +	if (enable_iopf)
> +		rc = iommufd_fault_iopf_enable(idev);
> +	return rc;
>   }
>   
>   static void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
> @@ -127,86 +102,15 @@ static void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
>   	mutex_unlock(&fault->mutex);
>   }
>   
> -static struct iommufd_attach_handle *
> -iommufd_device_get_attach_handle(struct iommufd_device *idev)
> -{
> -	struct iommu_attach_handle *handle;
> -
> -	handle = iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
> -	if (IS_ERR(handle))
> -		return NULL;
> -
> -	return to_iommufd_handle(handle);
> -}
> -
>   void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
> -				     struct iommufd_device *idev)
> +				     struct iommufd_device *idev,
> +				     struct iommufd_attach_handle *handle,
> +				     bool disable_iopf)
>   {
> -	struct iommufd_attach_handle *handle;
> -
> -	handle = iommufd_device_get_attach_handle(idev);
> -	iommu_detach_group_handle(hwpt->domain, idev->igroup->group);
> -	iommufd_auto_response_faults(hwpt, handle);
> -	iommufd_fault_iopf_disable(idev);
> -	kfree(handle);
> -}
> -
> -static int __fault_domain_replace_dev(struct iommufd_device *idev,
> -				      struct iommufd_hw_pagetable *hwpt,
> -				      struct iommufd_hw_pagetable *old)
> -{
> -	struct iommufd_attach_handle *handle, *curr = NULL;
> -	int ret;
> -
> -	if (old->fault)
> -		curr = iommufd_device_get_attach_handle(idev);
> -
> -	if (hwpt->fault) {
> -		handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> -		if (!handle)
> -			return -ENOMEM;
> -
> -		handle->idev = idev;
> -		ret = iommu_replace_group_handle(idev->igroup->group,
> -						 hwpt->domain, &handle->handle);
> -	} else {
> -		ret = iommu_replace_group_handle(idev->igroup->group,
> -						 hwpt->domain, NULL);
> -	}
> -
> -	if (!ret && curr) {
> -		iommufd_auto_response_faults(old, curr);
> -		kfree(curr);
> -	}
> -
> -	return ret;
> -}
> -
> -int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
> -				     struct iommufd_hw_pagetable *hwpt,
> -				     struct iommufd_hw_pagetable *old)
> -{
> -	bool iopf_off = !hwpt->fault && old->fault;
> -	bool iopf_on = hwpt->fault && !old->fault;
> -	int ret;
> -
> -	if (iopf_on) {
> -		ret = iommufd_fault_iopf_enable(idev);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	ret = __fault_domain_replace_dev(idev, hwpt, old);
> -	if (ret) {
> -		if (iopf_on)
> -			iommufd_fault_iopf_disable(idev);
> -		return ret;
> -	}
> -
> -	if (iopf_off)
> +	if (handle)
> +		iommufd_auto_response_faults(hwpt, handle);

no need to check handle. After this patch, both the non-fault and the fault
path will allocate handle. It cannot be used to isolate fault and non-fault
path. Also, the callers of iommufd_fault_domain_detach_dev() will check
hwpt->fault before calling it. So just call iommufd_auto_response_faults().

> +	if (disable_iopf)
>   		iommufd_fault_iopf_disable(idev);
> -
> -	return 0;
>   }
>   
>   void iommufd_fault_destroy(struct iommufd_object *obj)

-- 
Regards,
Yi Liu

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