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SubjectRE: [PATCH v10 04/11] vfio/pci: Add VFIO_REGION_TYPE_NESTED region type
Date
Hi Eric,

Just curious about your plan on this patch, I just heard my colleague would like
to reference the functions from this patch in his dsa driver work.

Regards,
Yi Liu

> From: Eric Auger <eric.auger@redhat.com>
> Sent: Saturday, March 21, 2020 12:19 AM
> To: eric.auger.pro@gmail.com; eric.auger@redhat.com; iommu@lists.linux-
> foundation.org; linux-kernel@vger.kernel.org; kvm@vger.kernel.org;
> kvmarm@lists.cs.columbia.edu; joro@8bytes.org; alex.williamson@redhat.com;
> jacob.jun.pan@linux.intel.com; Liu, Yi L <yi.l.liu@intel.com>; jean-
> philippe.brucker@arm.com; will.deacon@arm.com; robin.murphy@arm.com
> Cc: marc.zyngier@arm.com; peter.maydell@linaro.org; zhangfei.gao@gmail.com
> Subject: [PATCH v10 04/11] vfio/pci: Add VFIO_REGION_TYPE_NESTED region type
>
> Add a new specific DMA_FAULT region aiming to exposed nested mode
> translation faults.
>
> The region has a ring buffer that contains the actual fault
> records plus a header allowing to handle it (tail/head indices,
> max capacity, entry size). At the moment the region is dimensionned
> for 512 fault records.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
>
> v8 -> v9:
> - Use a single region instead of a prod/cons region
>
> v4 -> v5
> - check cons is not null in vfio_pci_check_cons_fault
>
> v3 -> v4:
> - use 2 separate regions, respectively in read and write modes
> - add the version capability
> ---
> drivers/vfio/pci/vfio_pci.c | 68 +++++++++++++++++++++++++++++
> drivers/vfio/pci/vfio_pci_private.h | 10 +++++
> drivers/vfio/pci/vfio_pci_rdwr.c | 45 +++++++++++++++++++
> include/uapi/linux/vfio.h | 35 +++++++++++++++
> 4 files changed, 158 insertions(+)
>
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 379a02c36e37..586b89debed5 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -260,6 +260,69 @@ int vfio_pci_set_power_state(struct vfio_pci_device *vdev,
> pci_power_t state)
> return ret;
> }
>
> +static void vfio_pci_dma_fault_release(struct vfio_pci_device *vdev,
> + struct vfio_pci_region *region)
> +{
> +}
> +
> +static int vfio_pci_dma_fault_add_capability(struct vfio_pci_device *vdev,
> + struct vfio_pci_region *region,
> + struct vfio_info_cap *caps)
> +{
> + struct vfio_region_info_cap_fault cap = {
> + .header.id = VFIO_REGION_INFO_CAP_DMA_FAULT,
> + .header.version = 1,
> + .version = 1,
> + };
> + return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
> +}
> +
> +static const struct vfio_pci_regops vfio_pci_dma_fault_regops = {
> + .rw = vfio_pci_dma_fault_rw,
> + .release = vfio_pci_dma_fault_release,
> + .add_capability = vfio_pci_dma_fault_add_capability,
> +};
> +
> +#define DMA_FAULT_RING_LENGTH 512
> +
> +static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
> +{
> + struct vfio_region_dma_fault *header;
> + size_t size;
> + int ret;
> +
> + mutex_init(&vdev->fault_queue_lock);
> +
> + /*
> + * We provision 1 page for the header and space for
> + * DMA_FAULT_RING_LENGTH fault records in the ring buffer.
> + */
> + size = ALIGN(sizeof(struct iommu_fault) *
> + DMA_FAULT_RING_LENGTH, PAGE_SIZE) + PAGE_SIZE;
> +
> + vdev->fault_pages = kzalloc(size, GFP_KERNEL);
> + if (!vdev->fault_pages)
> + return -ENOMEM;
> +
> + ret = vfio_pci_register_dev_region(vdev,
> + VFIO_REGION_TYPE_NESTED,
> + VFIO_REGION_SUBTYPE_NESTED_DMA_FAULT,
> + &vfio_pci_dma_fault_regops, size,
> + VFIO_REGION_INFO_FLAG_READ |
> VFIO_REGION_INFO_FLAG_WRITE,
> + vdev->fault_pages);
> + if (ret)
> + goto out;
> +
> + header = (struct vfio_region_dma_fault *)vdev->fault_pages;
> + header->entry_size = sizeof(struct iommu_fault);
> + header->nb_entries = DMA_FAULT_RING_LENGTH;
> + header->offset = sizeof(struct vfio_region_dma_fault);
> + return 0;
> +out:
> + kfree(vdev->fault_pages);
> + return ret;
> +}
> +
> static int vfio_pci_enable(struct vfio_pci_device *vdev)
> {
> struct pci_dev *pdev = vdev->pdev;
> @@ -358,6 +421,10 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
> }
> }
>
> + ret = vfio_pci_init_dma_fault_region(vdev);
> + if (ret)
> + goto disable_exit;
> +
> vfio_pci_probe_mmaps(vdev);
>
> return 0;
> @@ -1383,6 +1450,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
>
> vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
> kfree(vdev->region);
> + kfree(vdev->fault_pages);
> mutex_destroy(&vdev->ioeventfds_lock);
>
> if (!disable_idle_d3)
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index 8a2c7607d513..a392f50e3a99 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -119,6 +119,8 @@ struct vfio_pci_device {
> int ioeventfds_nr;
> struct eventfd_ctx *err_trigger;
> struct eventfd_ctx *req_trigger;
> + u8 *fault_pages;
> + struct mutex fault_queue_lock;
> struct list_head dummy_resources_list;
> struct mutex ioeventfds_lock;
> struct list_head ioeventfds_list;
> @@ -150,6 +152,14 @@ extern ssize_t vfio_pci_vga_rw(struct vfio_pci_device
> *vdev, char __user *buf,
> extern long vfio_pci_ioeventfd(struct vfio_pci_device *vdev, loff_t offset,
> uint64_t data, int count, int fd);
>
> +struct vfio_pci_fault_abi {
> + u32 entry_size;
> +};
> +
> +extern size_t vfio_pci_dma_fault_rw(struct vfio_pci_device *vdev,
> + char __user *buf, size_t count,
> + loff_t *ppos, bool iswrite);
> +
> extern int vfio_pci_init_perm_bits(void);
> extern void vfio_pci_uninit_perm_bits(void);
>
> diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
> index a87992892a9f..4004ab8cad0e 100644
> --- a/drivers/vfio/pci/vfio_pci_rdwr.c
> +++ b/drivers/vfio/pci/vfio_pci_rdwr.c
> @@ -274,6 +274,51 @@ ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char
> __user *buf,
> return done;
> }
>
> +size_t vfio_pci_dma_fault_rw(struct vfio_pci_device *vdev, char __user *buf,
> + size_t count, loff_t *ppos, bool iswrite)
> +{
> + unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) -
> VFIO_PCI_NUM_REGIONS;
> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
> + void *base = vdev->region[i].data;
> + int ret = -EFAULT;
> +
> + if (pos >= vdev->region[i].size)
> + return -EINVAL;
> +
> + count = min(count, (size_t)(vdev->region[i].size - pos));
> +
> + mutex_lock(&vdev->fault_queue_lock);
> +
> + if (iswrite) {
> + struct vfio_region_dma_fault *header =
> + (struct vfio_region_dma_fault *)base;
> + u32 new_tail;
> +
> + if (pos != 0 || count != 4) {
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> + if (copy_from_user((void *)&new_tail, buf, count))
> + goto unlock;
> +
> + if (new_tail > header->nb_entries) {
> + ret = -EINVAL;
> + goto unlock;
> + }
> + header->tail = new_tail;
> + } else {
> + if (copy_to_user(buf, base + pos, count))
> + goto unlock;
> + }
> + *ppos += count;
> + ret = count;
> +unlock:
> + mutex_unlock(&vdev->fault_queue_lock);
> + return ret;
> +}
> +
> +
> static int vfio_pci_ioeventfd_handler(void *opaque, void *unused)
> {
> struct vfio_pci_ioeventfd *ioeventfd = opaque;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9f2429eb1958..40d770f80e3d 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -330,6 +330,9 @@ struct vfio_region_info_cap_type {
> /* sub-types for VFIO_REGION_TYPE_GFX */
> #define VFIO_REGION_SUBTYPE_GFX_EDID (1)
>
> +#define VFIO_REGION_TYPE_NESTED (2)
> +#define VFIO_REGION_SUBTYPE_NESTED_DMA_FAULT (1)
> +
> /**
> * struct vfio_region_gfx_edid - EDID region layout.
> *
> @@ -708,6 +711,38 @@ struct vfio_device_ioeventfd {
>
> #define VFIO_DEVICE_IOEVENTFD _IO(VFIO_TYPE, VFIO_BASE + 16)
>
> +
> +/*
> + * Capability exposed by the DMA fault region
> + * @version: ABI version
> + */
> +#define VFIO_REGION_INFO_CAP_DMA_FAULT 6
> +
> +struct vfio_region_info_cap_fault {
> + struct vfio_info_cap_header header;
> + __u32 version;
> +};
> +
> +/*
> + * DMA Fault Region Layout
> + * @tail: index relative to the start of the ring buffer at which the
> + * consumer finds the next item in the buffer
> + * @entry_size: fault ring buffer entry size in bytes
> + * @nb_entries: max capacity of the fault ring buffer
> + * @offset: ring buffer offset relative to the start of the region
> + * @head: index relative to the start of the ring buffer at which the
> + * producer (kernel) inserts items into the buffers
> + */
> +struct vfio_region_dma_fault {
> + /* Write-Only */
> + __u32 tail;
> + /* Read-Only */
> + __u32 entry_size;
> + __u32 nb_entries;
> + __u32 offset;
> + __u32 head;
> +};
> +
> /* -------- API for Type1 VFIO IOMMU -------- */
>
> /**
> --
> 2.20.1

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