Reviewed-by: Kirti Wankhede <kwankh...@nvidia.com>

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 <nicol...@nvidia.com>
---
  .../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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