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

From: Eric Farman
Date: Fri Jul 08 2022 - 16:30:06 EST

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On Tue, 2022-07-05 at 23:27 -0700, 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 +++++++++------
> ----

Acked-by: Eric Farman <farman@xxxxxxxxxxxxx>

> 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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