Date:   Wed, 6 Jul 2022 23:08:58 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Nicolin Chen <nicolinc@...dia.com>, corbet@....net,
        hca@...ux.ibm.com, gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
        zhenyuw@...ux.intel.com, zhi.a.wang@...el.com,
        jani.nikula@...ux.intel.com, joonas.lahtinen@...ux.intel.com,
        rodrigo.vivi@...el.com, tvrtko.ursulin@...ux.intel.com,
        airlied@...ux.ie, daniel@...ll.ch, farman@...ux.ibm.com,
        mjrosato@...ux.ibm.com, pasic@...ux.ibm.com, vneethv@...ux.ibm.com,
        oberpar@...ux.ibm.com, freude@...ux.ibm.com,
        akrowiak@...ux.ibm.com, jjherne@...ux.ibm.com,
        alex.williamson@...hat.com, cohuck@...hat.com, jgg@...dia.com,
        kevin.tian@...el.com, hch@...radead.org
Cc:     jchrist@...ux.ibm.com, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-s390@...r.kernel.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        Tarun Gupta <targupta@...dia.com>, Neo Jia <cjia@...dia.com>,
        Shounak Deshpande <shdeshpande@...dia.com>
Subject: Re: [RFT][PATCH v2 4/9] vfio: Pass in starting IOVA to
 vfio_pin/unpin_pages API


Reviewed by: Kirti Wankhede <kwankhede@...dia.com>


On 7/6/2022 11:57 AM, Nicolin Chen wrote:
> The vfio_pin/unpin_pages() so far accepted arrays of PFNs of user IOVA.
> Among all three callers, there was only one caller possibly passing in
> a non-contiguous PFN list, which is now ensured to have contiguous PFN
> inputs too.
> 
> Pass in the starting address with "iova" alone to simplify things, so
> callers no longer need to maintain a PFN list or to pin/unpin one page
> at a time. This also allows VFIO to use more efficient implementations
> of pin/unpin_pages.
> 
> For now, also update vfio_iommu_type1 to fit this new parameter too,
> while keeping its input intact (being user_iova) since we don't want
> to spend too much effort swapping its parameters and local variables
> at that level.
> 
> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>   .../driver-api/vfio-mediated-device.rst       |  4 +--
>   drivers/gpu/drm/i915/gvt/kvmgt.c              | 24 ++++++-----------
>   drivers/s390/cio/vfio_ccw_cp.c                |  4 +--
>   drivers/s390/crypto/vfio_ap_ops.c             |  9 +++----
>   drivers/vfio/vfio.c                           | 27 +++++++++----------
>   drivers/vfio/vfio.h                           |  4 +--
>   drivers/vfio/vfio_iommu_type1.c               | 17 ++++++------
>   include/linux/vfio.h                          |  5 ++--
>   8 files changed, 40 insertions(+), 54 deletions(-)
> 
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> index b0fdf76b339a..ea32a0f13ddb 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -262,10 +262,10 @@ Translation APIs for Mediated Devices
>   The following APIs are provided for translating user pfn to host pfn in a VFIO
>   driver::
>   
> -	int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
> +	int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
>   				  int npage, int prot, unsigned long *phys_pfn);
>   
> -	void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
> +	void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova,
>   				    int npage);
>   
>   These functions call back into the back-end IOMMU module by using the pin_pages
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 8c67c9aba82d..ea6041fa48ac 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -231,16 +231,8 @@ static void intel_gvt_cleanup_vgpu_type_groups(struct intel_gvt *gvt)
>   static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
>   		unsigned long size)
>   {
> -	int total_pages;
> -	int npage;
> -
> -	total_pages = roundup(size, PAGE_SIZE) / PAGE_SIZE;
> -
> -	for (npage = 0; npage < total_pages; npage++) {
> -		unsigned long cur_gfn = gfn + npage;
> -
> -		vfio_unpin_pages(&vgpu->vfio_device, &cur_gfn, 1);
> -	}
> +	vfio_unpin_pages(&vgpu->vfio_device, gfn << PAGE_SHIFT,
> +			 roundup(size, PAGE_SIZE) / PAGE_SIZE);
>   }
>   
>   /* Pin a normal or compound guest page for dma. */
> @@ -258,14 +250,14 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
>   	 * on stack to hold pfns.
>   	 */
>   	for (npage = 0; npage < total_pages; npage++) {
> -		unsigned long cur_gfn = gfn + npage;
> +		dma_addr_t cur_iova = (gfn + npage) << PAGE_SHIFT;
>   		unsigned long pfn;
>   
> -		ret = vfio_pin_pages(&vgpu->vfio_device, &cur_gfn, 1,
> +		ret = vfio_pin_pages(&vgpu->vfio_device, cur_iova, 1,
>   				     IOMMU_READ | IOMMU_WRITE, &pfn);
>   		if (ret != 1) {
> -			gvt_vgpu_err("vfio_pin_pages failed for gfn 0x%lx, ret %d\n",
> -				     cur_gfn, ret);
> +			gvt_vgpu_err("vfio_pin_pages failed for iova %pad, ret %d\n",
> +				     &cur_iova, ret);
>   			goto err;
>   		}
>   
> @@ -309,7 +301,7 @@ static int gvt_dma_map_page(struct intel_vgpu *vgpu, unsigned long gfn,
>   	if (dma_mapping_error(dev, *dma_addr)) {
>   		gvt_vgpu_err("DMA mapping failed for pfn 0x%lx, ret %d\n",
>   			     page_to_pfn(page), ret);
> -		gvt_unpin_guest_page(vgpu, gfn, size);
> +		gvt_unpin_guest_page(vgpu, gfn << PAGE_SHIFT, size);
>   		return -ENOMEM;
>   	}
>   
> @@ -322,7 +314,7 @@ static void gvt_dma_unmap_page(struct intel_vgpu *vgpu, unsigned long gfn,
>   	struct device *dev = vgpu->gvt->gt->i915->drm.dev;
>   
>   	dma_unmap_page(dev, dma_addr, size, DMA_BIDIRECTIONAL);
> -	gvt_unpin_guest_page(vgpu, gfn, size);
> +	gvt_unpin_guest_page(vgpu, gfn << PAGE_SHIFT, size);
>   }
>   
>   static struct gvt_dma *__gvt_cache_find_dma_addr(struct intel_vgpu *vgpu,
> diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
> index 3b94863ad24e..a739262f988d 100644
> --- a/drivers/s390/cio/vfio_ccw_cp.c
> +++ b/drivers/s390/cio/vfio_ccw_cp.c
> @@ -114,7 +114,7 @@ static void pfn_array_unpin(struct pfn_array *pa,
>   			continue;
>   		}
>   
> -		vfio_unpin_pages(vdev, first, npage);
> +		vfio_unpin_pages(vdev, *first << PAGE_SHIFT, npage);
>   		unpinned += npage;
>   		npage = 1;
>   	}
> @@ -146,7 +146,7 @@ static int pfn_array_pin(struct pfn_array *pa, struct vfio_device *vdev)
>   			continue;
>   		}
>   
> -		ret = vfio_pin_pages(vdev, first, npage,
> +		ret = vfio_pin_pages(vdev, *first << PAGE_SHIFT, npage,
>   				     IOMMU_READ | IOMMU_WRITE,
>   				     &pa->pa_pfn[pinned]);
>   		if (ret < 0) {
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index bb869b28cebd..8a2018ab3cf0 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -124,7 +124,7 @@ static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q)
>   		q->saved_isc = VFIO_AP_ISC_INVALID;
>   	}
>   	if (q->saved_pfn && !WARN_ON(!q->matrix_mdev)) {
> -		vfio_unpin_pages(&q->matrix_mdev->vdev, &q->saved_pfn, 1);
> +		vfio_unpin_pages(&q->matrix_mdev->vdev, q->saved_pfn << PAGE_SHIFT, 1);
>   		q->saved_pfn = 0;
>   	}
>   }
> @@ -258,7 +258,7 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
>   		return status;
>   	}
>   
> -	ret = vfio_pin_pages(&q->matrix_mdev->vdev, &g_pfn, 1,
> +	ret = vfio_pin_pages(&q->matrix_mdev->vdev, g_pfn << PAGE_SHIFT, 1,
>   			     IOMMU_READ | IOMMU_WRITE, &h_pfn);
>   	switch (ret) {
>   	case 1:
> @@ -301,7 +301,7 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
>   		break;
>   	case AP_RESPONSE_OTHERWISE_CHANGED:
>   		/* We could not modify IRQ setings: clear new configuration */
> -		vfio_unpin_pages(&q->matrix_mdev->vdev, &g_pfn, 1);
> +		vfio_unpin_pages(&q->matrix_mdev->vdev, g_pfn << PAGE_SHIFT, 1);
>   		kvm_s390_gisc_unregister(kvm, isc);
>   		break;
>   	default:
> @@ -1248,9 +1248,8 @@ static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb,
>   
>   	if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) {
>   		struct vfio_iommu_type1_dma_unmap *unmap = data;
> -		unsigned long g_pfn = unmap->iova >> PAGE_SHIFT;
>   
> -		vfio_unpin_pages(&matrix_mdev->vdev, &g_pfn, 1);
> +		vfio_unpin_pages(&matrix_mdev->vdev, unmap->iova, 1);
>   		return NOTIFY_OK;
>   	}
>   
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 01f45ec70a3d..813b517c973e 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1910,17 +1910,17 @@ int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr, int num_irqs,
>   EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
>   
>   /*
> - * Pin a set of guest PFNs and return their associated host PFNs for local
> + * Pin contiguous guest pages and return their associated host pages for local
>    * domain only.
>    * @device [in]  : device
> - * @user_pfn [in]: array of user/guest PFNs to be pinned.
> - * @npage [in]   : count of elements in user_pfn array.  This count should not
> + * @iova [in]    : starting IOVA of user/guest pages to be pinned.
> + * @npage [in]   : count of pages to be pinned.  This count should not
>    *		   be greater VFIO_PIN_PAGES_MAX_ENTRIES.
>    * @prot [in]    : protection flags
>    * @phys_pfn[out]: array of host PFNs
>    * Return error or number of pages pinned.
>    */
> -int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
> +int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
>   		   int npage, int prot, unsigned long *phys_pfn)
>   {
>   	struct vfio_container *container;
> @@ -1928,8 +1928,7 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
>   	struct vfio_iommu_driver *driver;
>   	int ret;
>   
> -	if (!user_pfn || !phys_pfn || !npage ||
> -	    !vfio_assert_device_open(device))
> +	if (!phys_pfn || !npage || !vfio_assert_device_open(device))
>   		return -EINVAL;
>   
>   	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
> @@ -1943,7 +1942,7 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
>   	driver = container->iommu_driver;
>   	if (likely(driver && driver->ops->pin_pages))
>   		ret = driver->ops->pin_pages(container->iommu_data,
> -					     group->iommu_group, user_pfn,
> +					     group->iommu_group, iova,
>   					     npage, prot, phys_pfn);
>   	else
>   		ret = -ENOTTY;
> @@ -1953,20 +1952,18 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
>   EXPORT_SYMBOL(vfio_pin_pages);
>   
>   /*
> - * Unpin set of host PFNs for local domain only.
> + * Unpin contiguous host pages for local domain only.
>    * @device [in]  : device
> - * @user_pfn [in]: array of user/guest PFNs to be unpinned. Number of user/guest
> - *		   PFNs should not be greater than VFIO_PIN_PAGES_MAX_ENTRIES.
> - * @npage [in]   : count of elements in user_pfn array.  This count should not
> + * @iova [in]    : starting address of user/guest pages to be unpinned.
> + * @npage [in]   : count of pages to be unpinned.  This count should not
>    *                 be greater than VFIO_PIN_PAGES_MAX_ENTRIES.
>    */
> -void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
> -		      int npage)
> +void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova, int npage)
>   {
>   	struct vfio_container *container;
>   	struct vfio_iommu_driver *driver;
>   
> -	if (WARN_ON_ONCE(!user_pfn || !npage || !vfio_assert_device_open(device)))
> +	if (WARN_ON_ONCE(!npage || !vfio_assert_device_open(device)))
>   		return;
>   
>   	if (WARN_ON_ONCE(npage > VFIO_PIN_PAGES_MAX_ENTRIES))
> @@ -1979,7 +1976,7 @@ void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
>   	if (WARN_ON_ONCE(unlikely(!driver || !driver->ops->unpin_pages)))
>   		return;
>   
> -	driver->ops->unpin_pages(container->iommu_data, user_pfn, npage);
> +	driver->ops->unpin_pages(container->iommu_data, iova, npage);
>   }
>   EXPORT_SYMBOL(vfio_unpin_pages);
>   
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index bef4edf58138..dbcd0e8c031b 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -50,11 +50,11 @@ struct vfio_iommu_driver_ops {
>   					struct iommu_group *group);
>   	int		(*pin_pages)(void *iommu_data,
>   				     struct iommu_group *group,
> -				     unsigned long *user_pfn,
> +				     dma_addr_t user_iova,
>   				     int npage, int prot,
>   				     unsigned long *phys_pfn);
>   	void		(*unpin_pages)(void *iommu_data,
> -				       unsigned long *user_pfn, int npage);
> +				       dma_addr_t user_iova, int npage);
>   	int		(*register_notifier)(void *iommu_data,
>   					     unsigned long *events,
>   					     struct notifier_block *nb);
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 08613edaf722..f10d0c4b1f26 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -828,7 +828,7 @@ static int vfio_unpin_page_external(struct vfio_dma *dma, dma_addr_t iova,
>   
>   static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   				      struct iommu_group *iommu_group,
> -				      unsigned long *user_pfn,
> +				      dma_addr_t user_iova,
>   				      int npage, int prot,
>   				      unsigned long *phys_pfn)
>   {
> @@ -840,7 +840,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   	bool do_accounting;
>   	dma_addr_t iova;
>   
> -	if (!iommu || !user_pfn || !phys_pfn)
> +	if (!iommu || !phys_pfn)
>   		return -EINVAL;
>   
>   	/* Supported for v2 version only */
> @@ -856,7 +856,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   again:
>   	if (iommu->vaddr_invalid_count) {
>   		for (i = 0; i < npage; i++) {
> -			iova = user_pfn[i] << PAGE_SHIFT;
> +			iova = user_iova + PAGE_SIZE * i;
>   			ret = vfio_find_dma_valid(iommu, iova, PAGE_SIZE, &dma);
>   			if (ret < 0)
>   				goto pin_done;
> @@ -881,7 +881,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   	for (i = 0; i < npage; i++) {
>   		struct vfio_pfn *vpfn;
>   
> -		iova = user_pfn[i] << PAGE_SHIFT;
> +		iova = user_iova + PAGE_SIZE * i;
>   		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
>   		if (!dma) {
>   			ret = -EINVAL;
> @@ -938,7 +938,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   	for (j = 0; j < i; j++) {
>   		dma_addr_t iova;
>   
> -		iova = user_pfn[j] << PAGE_SHIFT;
> +		iova = user_iova + PAGE_SIZE * j;
>   		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
>   		vfio_unpin_page_external(dma, iova, do_accounting);
>   		phys_pfn[j] = 0;
> @@ -949,13 +949,13 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>   }
>   
>   static void vfio_iommu_type1_unpin_pages(void *iommu_data,
> -					 unsigned long *user_pfn, int npage)
> +					dma_addr_t user_iova, int npage)
>   {
>   	struct vfio_iommu *iommu = iommu_data;
>   	bool do_accounting;
>   	int i;
>   
> -	if (WARN_ON_ONCE(!iommu || !user_pfn || npage <= 0))
> +	if (WARN_ON_ONCE(!iommu || npage <= 0))
>   		return;
>   
>   	/* Supported for v2 version only */
> @@ -966,10 +966,9 @@ static void vfio_iommu_type1_unpin_pages(void *iommu_data,
>   
>   	do_accounting = list_empty(&iommu->domain_list);
>   	for (i = 0; i < npage; i++) {
> +		dma_addr_t iova = user_iova + PAGE_SIZE * i;
>   		struct vfio_dma *dma;
> -		dma_addr_t iova;
>   
> -		iova = user_pfn[i] << PAGE_SHIFT;
>   		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
>   		if (!dma)
>   			break;
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index d0844ecdc961..c3e441c0bf4b 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -147,10 +147,9 @@ bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
>   
>   #define VFIO_PIN_PAGES_MAX_ENTRIES	(PAGE_SIZE/sizeof(unsigned long))
>   
> -int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
> +int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
>   		   int npage, int prot, unsigned long *phys_pfn);
> -void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
> -		      int npage);
> +void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova, int npage);
>   int vfio_dma_rw(struct vfio_device *device, dma_addr_t user_iova,
>   		void *data, size_t len, bool write);
>   

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