Re: [RFT][PATCH v2 9/9] vfio: Replace phys_pfn with pages for vfio_pin_pages()

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Reviewed-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>

On 7/6/2022 11:57 AM, Nicolin Chen wrote:
Most of the callers of vfio_pin_pages() want "struct page *" and the
low-level mm code to pin pages returns a list of "struct page *" too.
So there's no gain in converting "struct page *" to PFN in between.

Replace the output parameter "phys_pfn" list with a "pages" list, to
simplify callers. This also allows us to replace the vfio_iommu_type1
implementation with a more efficient one.

For now, also update vfio_iommu_type1 to fit this new parameter too.

Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
  .../driver-api/vfio-mediated-device.rst       |  2 +-
  drivers/gpu/drm/i915/gvt/kvmgt.c              | 19 ++++++-------------
  drivers/s390/cio/vfio_ccw_cp.c                | 19 +++++++++----------
  drivers/s390/crypto/vfio_ap_ops.c             |  6 +++---
  drivers/vfio/vfio.c                           |  8 ++++----
  drivers/vfio/vfio.h                           |  2 +-
  drivers/vfio/vfio_iommu_type1.c               | 19 +++++++++++--------
  include/linux/vfio.h                          |  2 +-
  8 files changed, 36 insertions(+), 41 deletions(-)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index ea32a0f13ddb..ba5fefcdae1a 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -263,7 +263,7 @@ The following APIs are provided for translating user pfn to host pfn in a VFIO
  driver::
int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
-				  int npage, int prot, unsigned long *phys_pfn);
+				  int npage, int prot, struct page **pages);
void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova,
  				    int npage);
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index ea6041fa48ac..3a49471dcc16 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -239,7 +239,7 @@ static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
  static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
  		unsigned long size, struct page **page)
  {
-	unsigned long base_pfn = 0;
+	struct page *base_page = NULL;
  	int total_pages;
  	int npage;
  	int ret;
@@ -251,26 +251,19 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
  	 */
  	for (npage = 0; npage < total_pages; npage++) {
  		dma_addr_t cur_iova = (gfn + npage) << PAGE_SHIFT;
-		unsigned long pfn;
+		struct page *cur_page;
ret = vfio_pin_pages(&vgpu->vfio_device, cur_iova, 1,
-				     IOMMU_READ | IOMMU_WRITE, &pfn);
+				     IOMMU_READ | IOMMU_WRITE, &cur_page);
  		if (ret != 1) {
  			gvt_vgpu_err("vfio_pin_pages failed for iova %pad, ret %d\n",
  				     &cur_iova, ret);
  			goto err;
  		}
- if (!pfn_valid(pfn)) {
-			gvt_vgpu_err("pfn 0x%lx is not mem backed\n", pfn);
-			npage++;
-			ret = -EFAULT;
-			goto err;
-		}
-
  		if (npage == 0)
-			base_pfn = pfn;
-		else if (base_pfn + npage != pfn) {
+			base_page = cur_page;
+		else if (base_page + npage != cur_page) {
  			gvt_vgpu_err("The pages are not continuous\n");
  			ret = -EINVAL;
  			npage++;
@@ -278,7 +271,7 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
  		}
  	}
- *page = pfn_to_page(base_pfn);
+	*page = base_page;
  	return 0;
  err:
  	gvt_unpin_guest_page(vgpu, gfn, npage * PAGE_SIZE);
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index cd4ec4f6d6ff..8963f452f963 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -22,8 +22,8 @@
  struct page_array {
  	/* Array that stores pages need to pin. */
  	dma_addr_t		*pa_iova;
-	/* Array that receives PFNs of the pages pinned. */
-	unsigned long		*pa_pfn;
+	/* Array that receives the pinned pages. */
+	struct page		**pa_page;
  	/* Number of pages pinned from @pa_iova. */
  	int			pa_nr;
  };
@@ -68,19 +68,19 @@ static int page_array_alloc(struct page_array *pa, u64 iova, unsigned int len)
  		return -EINVAL;
pa->pa_iova = kcalloc(pa->pa_nr,
-			      sizeof(*pa->pa_iova) + sizeof(*pa->pa_pfn),
+			      sizeof(*pa->pa_iova) + sizeof(*pa->pa_page),
  			      GFP_KERNEL);
  	if (unlikely(!pa->pa_iova)) {
  		pa->pa_nr = 0;
  		return -ENOMEM;
  	}
-	pa->pa_pfn = (unsigned long *)&pa->pa_iova[pa->pa_nr];
+	pa->pa_page = (struct page **)&pa->pa_iova[pa->pa_nr];
pa->pa_iova[0] = iova;
-	pa->pa_pfn[0] = -1ULL;
+	pa->pa_page[0] = NULL;
  	for (i = 1; i < pa->pa_nr; i++) {
  		pa->pa_iova[i] = pa->pa_iova[i - 1] + PAGE_SIZE;
-		pa->pa_pfn[i] = -1ULL;
+		pa->pa_page[i] = NULL;
  	}
return 0;
@@ -144,7 +144,7 @@ static int page_array_pin(struct page_array *pa, struct vfio_device *vdev)
ret = vfio_pin_pages(vdev, *first, npage,
  				     IOMMU_READ | IOMMU_WRITE,
-				     &pa->pa_pfn[pinned]);
+				     &pa->pa_page[pinned]);
  		if (ret < 0) {
  			goto err_out;
  		} else if (ret > 0 && ret != npage) {
@@ -195,7 +195,7 @@ static inline void page_array_idal_create_words(struct page_array *pa,
  	 */
for (i = 0; i < pa->pa_nr; i++)
-		idaws[i] = pa->pa_pfn[i] << PAGE_SHIFT;
+		idaws[i] = page_to_phys(pa->pa_page[i]);
/* Adjust the first IDAW, since it may not start on a page boundary */
  	idaws[0] += pa->pa_iova[0] & (PAGE_SIZE - 1);
@@ -246,8 +246,7 @@ static long copy_from_iova(struct vfio_device *vdev, void *to, u64 iova,
l = n;
  	for (i = 0; i < pa.pa_nr; i++) {
-		struct page *page = pfn_to_page(pa.pa_pfn[i]);
-		void *from = kmap_local_page(page);
+		void *from = kmap_local_page(pa.pa_page[i]);
m = PAGE_SIZE;
  		if (i == 0) {
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6945e0ddc08c..b0972ca0dfa3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -234,9 +234,9 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
  	struct ap_qirq_ctrl aqic_gisa = {};
  	struct ap_queue_status status = {};
  	struct kvm_s390_gisa *gisa;
+	struct page *h_page;
  	int nisc;
  	struct kvm *kvm;
-	unsigned long h_pfn;
  	phys_addr_t h_nib;
  	dma_addr_t nib;
  	int ret;
@@ -251,7 +251,7 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
  	}
ret = vfio_pin_pages(&q->matrix_mdev->vdev, nib, 1,
-			     IOMMU_READ | IOMMU_WRITE, &h_pfn);
+			     IOMMU_READ | IOMMU_WRITE, &h_page);
  	switch (ret) {
  	case 1:
  		break;
@@ -267,7 +267,7 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
  	kvm = q->matrix_mdev->kvm;
  	gisa = kvm->arch.gisa_int.origin;
- h_nib = (h_pfn << PAGE_SHIFT) | (nib & ~PAGE_MASK);
+	h_nib = page_to_phys(h_page) | (nib & ~PAGE_MASK);
  	aqic_gisa.gisc = isc;
nisc = kvm_s390_gisc_register(kvm, isc);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index b95ec2d78966..96b758e06c4a 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1917,18 +1917,18 @@ EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
   * @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
+ * @pages[out]   : array of host pages
   * Return error or number of pages pinned.
   */
  int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
-		   int npage, int prot, unsigned long *phys_pfn)
+		   int npage, int prot, struct page **pages)
  {
  	struct vfio_container *container;
  	struct vfio_group *group = device->group;
  	struct vfio_iommu_driver *driver;
  	int ret;
- if (!phys_pfn || !npage || !vfio_assert_device_open(device))
+	if (!pages || !npage || !vfio_assert_device_open(device))
  		return -EINVAL;
if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
@@ -1943,7 +1943,7 @@ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
  	if (likely(driver && driver->ops->pin_pages))
  		ret = driver->ops->pin_pages(container->iommu_data,
  					     group->iommu_group, iova,
-					     npage, prot, phys_pfn);
+					     npage, prot, pages);
  	else
  		ret = -ENOTTY;
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index dbcd0e8c031b..dbfad8e20581 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -52,7 +52,7 @@ struct vfio_iommu_driver_ops {
  				     struct iommu_group *group,
  				     dma_addr_t user_iova,
  				     int npage, int prot,
-				     unsigned long *phys_pfn);
+				     struct page **pages);
  	void		(*unpin_pages)(void *iommu_data,
  				       dma_addr_t user_iova, int npage);
  	int		(*register_notifier)(void *iommu_data,
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index f10d0c4b1f26..de342d82b154 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -830,7 +830,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
  				      struct iommu_group *iommu_group,
  				      dma_addr_t user_iova,
  				      int npage, int prot,
-				      unsigned long *phys_pfn)
+				      struct page **pages)
  {
  	struct vfio_iommu *iommu = iommu_data;
  	struct vfio_iommu_group *group;
@@ -840,7 +840,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
  	bool do_accounting;
  	dma_addr_t iova;
- if (!iommu || !phys_pfn)
+	if (!iommu || !pages)
  		return -EINVAL;
/* Supported for v2 version only */
@@ -879,6 +879,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
  	do_accounting = list_empty(&iommu->domain_list);
for (i = 0; i < npage; i++) {
+		unsigned long phys_pfn;
  		struct vfio_pfn *vpfn;
iova = user_iova + PAGE_SIZE * i;
@@ -895,23 +896,25 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
vpfn = vfio_iova_get_vfio_pfn(dma, iova);
  		if (vpfn) {
-			phys_pfn[i] = vpfn->pfn;
+			pages[i] = pfn_to_page(vpfn->pfn);
  			continue;
  		}
remote_vaddr = dma->vaddr + (iova - dma->iova);
-		ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],
+		ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn,
  					     do_accounting);
  		if (ret)
  			goto pin_unwind;
- ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);
+		ret = vfio_add_to_pfn_list(dma, iova, phys_pfn);
  		if (ret) {
-			if (put_pfn(phys_pfn[i], dma->prot) && do_accounting)
+			if (put_pfn(phys_pfn, dma->prot) && do_accounting)
  				vfio_lock_acct(dma, -1, true);
  			goto pin_unwind;
  		}
+ pages[i] = pfn_to_page(phys_pfn);
+
  		if (iommu->dirty_page_tracking) {
  			unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
@@ -934,14 +937,14 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
  	goto pin_done;
pin_unwind:
-	phys_pfn[i] = 0;
+	pages[i] = NULL;
  	for (j = 0; j < i; j++) {
  		dma_addr_t iova;
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;
+		pages[j] = NULL;
  	}
  pin_done:
  	mutex_unlock(&iommu->lock);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 9108de34a79b..c76a2c492bbd 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -148,7 +148,7 @@ 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, dma_addr_t iova,
-		   int npage, int prot, unsigned long *phys_pfn);
+		   int npage, int prot, struct page **pages);
  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 iova,
  		void *data, size_t len, bool write);



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