On Wed, 5 Apr 2023 11:01:34 -0700
<ankita@xxxxxxxxxx> wrote:
> From: Ankit Agrawal <ankita@xxxxxxxxxx>
>
> The nvgpu-vfio-pci module maps QEMU VMA to device memory through
> remap_pfn_range(). The new mechanism to handle poison on memory not backed
> by struct page is leveraged here.
>
> nvgpu-vfio-pci defines a function pfn_memory_failure() to get the ECC PFN
> from the MM. The function is registered with kernel MM along with the
> address space and PFN range through register_pfn_address_space().
>
> Track poisoned PFN in the nvgpu-vfio-pci module as bitmap with a bit per
> PFN. The PFN is communicated by the kernel MM to the module through the
> failure function, which sets the appropriate bit in the bitmap.
>
> Register a VMA fault ops for the module. It returns VM_FAULT_HWPOISON
> in case the bit for the PFN is set in the bitmap.
>
> Clear bitmap on reset to reflect the clean state of the device memory
> after reset.
>
> Signed-off-by: Ankit Agrawal <ankita@xxxxxxxxxx>
> ---
> drivers/vfio/pci/nvgpu/main.c | 116 ++++++++++++++++++++++++++++++++--
> 1 file changed, 110 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vfio/pci/nvgpu/main.c b/drivers/vfio/pci/nvgpu/main.c
> index 2dd8cc6e0145..8ccd3fe33a0f 100644
> --- a/drivers/vfio/pci/nvgpu/main.c
> +++ b/drivers/vfio/pci/nvgpu/main.c
> @@ -5,6 +5,8 @@
>
> #include <linux/pci.h>
> #include <linux/vfio_pci_core.h>
> +#include <linux/bitmap.h>
> +#include <linux/memory-failure.h>
>
> #define DUMMY_PFN \
> (((nvdev->mem_prop.hpa + nvdev->mem_prop.mem_length) >> PAGE_SHIFT) - 1)
> @@ -12,12 +14,78 @@
> struct dev_mem_properties {
> uint64_t hpa;
> uint64_t mem_length;
> + unsigned long *pfn_bitmap;
> int bar1_start_offset;
> };
>
> struct nvgpu_vfio_pci_core_device {
> struct vfio_pci_core_device core_device;
> struct dev_mem_properties mem_prop;
> + struct pfn_address_space pfn_address_space;
> +};
> +
> +void nvgpu_vfio_pci_pfn_memory_failure(struct pfn_address_space *pfn_space,
> + unsigned long pfn)
> +{
> + struct nvgpu_vfio_pci_core_device *nvdev = container_of(
> + pfn_space, struct nvgpu_vfio_pci_core_device, pfn_address_space);
> +
> + /*
> + * MM has called to notify a poisoned page. Track that in the bitmap.
> + */
> + __set_bit(pfn - (pfn_space->node.start), nvdev->mem_prop.pfn_bitmap);
> +}
> +
> +struct pfn_address_space_ops nvgpu_vfio_pci_pas_ops = {
> + .failure = nvgpu_vfio_pci_pfn_memory_failure,
> +};
> +
> +static int
> +nvgpu_vfio_pci_register_pfn_range(struct nvgpu_vfio_pci_core_device *nvdev,
> + struct vm_area_struct *vma)
> +{
> + unsigned long nr_pages;
> + int ret = 0;
> +
> + nr_pages = nvdev->mem_prop.mem_length >> PAGE_SHIFT;
> +
> + nvdev->pfn_address_space.node.start = vma->vm_pgoff;
> + nvdev->pfn_address_space.node.last = vma->vm_pgoff + nr_pages - 1;
> + nvdev->pfn_address_space.ops = &nvgpu_vfio_pci_pas_ops;
> + nvdev->pfn_address_space.mapping = vma->vm_file->f_mapping;
> +
> + ret = register_pfn_address_space(&(nvdev->pfn_address_space));
> +
> + return ret;
> +}
> +
> +static vm_fault_t nvgpu_vfio_pci_fault(struct vm_fault *vmf)
> +{
> + unsigned long mem_offset = vmf->pgoff - vmf->vma->vm_pgoff;
> + struct nvgpu_vfio_pci_core_device *nvdev = container_of(
> + vmf->vma->vm_file->private_data,
> + struct nvgpu_vfio_pci_core_device, core_device.vdev);
> + int ret;
> +
> + /*
> + * Check if the page is poisoned.
> + */
> + if (mem_offset < (nvdev->mem_prop.mem_length >> PAGE_SHIFT) &&
> + test_bit(mem_offset, nvdev->mem_prop.pfn_bitmap))
> + return VM_FAULT_HWPOISON;
> +
> + ret = remap_pfn_range(vmf->vma,
> + vmf->vma->vm_start + (mem_offset << PAGE_SHIFT),
> + DUMMY_PFN, PAGE_SIZE,
> + vmf->vma->vm_page_prot);
> + if (ret)
> + return VM_FAULT_ERROR;
> +
> + return VM_FAULT_NOPAGE;
> +}
> +
> +static const struct vm_operations_struct nvgpu_vfio_pci_mmap_ops = {
> + .fault = nvgpu_vfio_pci_fault,
> };
>
> static int vfio_get_bar1_start_offset(struct vfio_pci_core_device *vdev)
> @@ -26,8 +94,9 @@ static int vfio_get_bar1_start_offset(struct vfio_pci_core_device *vdev)
>
> pci_read_config_byte(vdev->pdev, 0x10, &val);
> /*
> - * The BAR1 start offset in the PCI config space depends on the BAR0size.
> - * Check if the BAR0 is 64b and return the approproiate BAR1 offset.
> + * The BAR1 start offset in the PCI config space depends on the BAR0
> + * size. Check if the BAR0 is 64b and return the approproiate BAR1
> + * offset.
> */
> if (val & PCI_BASE_ADDRESS_MEM_TYPE_64)
> return VFIO_PCI_BAR2_REGION_INDEX;
> @@ -54,6 +123,16 @@ static int nvgpu_vfio_pci_open_device(struct vfio_device *core_vdev)
> return ret;
> }
>
> +void nvgpu_vfio_pci_close_device(struct vfio_device *core_vdev)
> +{
> + struct nvgpu_vfio_pci_core_device *nvdev = container_of(
> + core_vdev, struct nvgpu_vfio_pci_core_device, core_device.vdev);
> +
> + unregister_pfn_address_space(&(nvdev->pfn_address_space));
> +
> + vfio_pci_core_close_device(core_vdev);
> +}
> +
> int nvgpu_vfio_pci_mmap(struct vfio_device *core_vdev,
> struct vm_area_struct *vma)
> {
> @@ -93,8 +172,11 @@ int nvgpu_vfio_pci_mmap(struct vfio_device *core_vdev,
> return ret;
>
> vma->vm_pgoff = start_pfn + pgoff;
> + vma->vm_ops = &nvgpu_vfio_pci_mmap_ops;
>
> - return 0;
> + ret = nvgpu_vfio_pci_register_pfn_range(nvdev, vma);
> +
> + return ret;
> }
>
> long nvgpu_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
> @@ -140,7 +222,14 @@ long nvgpu_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
> }
>
> return vfio_pci_core_ioctl(core_vdev, cmd, arg);
> -
> + case VFIO_DEVICE_RESET:
> + /*
> + * Resetting the GPU clears up the poisoned page. Reset the
> + * poisoned page bitmap.
> + */
> + memset(nvdev->mem_prop.pfn_bitmap, 0,
> + nvdev->mem_prop.mem_length >> (PAGE_SHIFT + 3));
> + return vfio_pci_core_ioctl(core_vdev, cmd, arg);
> default:
> return vfio_pci_core_ioctl(core_vdev, cmd, arg);
> }
> @@ -151,7 +240,7 @@ static const struct vfio_device_ops nvgpu_vfio_pci_ops = {
> .init = vfio_pci_core_init_dev,
> .release = vfio_pci_core_release_dev,
> .open_device = nvgpu_vfio_pci_open_device,
> - .close_device = vfio_pci_core_close_device,
> + .close_device = nvgpu_vfio_pci_close_device,
> .ioctl = nvgpu_vfio_pci_ioctl,
> .read = vfio_pci_core_read,
> .write = vfio_pci_core_write,
> @@ -188,7 +277,20 @@ nvgpu_vfio_pci_fetch_memory_property(struct pci_dev *pdev,
>
> ret = device_property_read_u64(&(pdev->dev), "nvidia,gpu-mem-size",
> &(nvdev->mem_prop.mem_length));
> - return ret;
> + if (ret)
> + return ret;
> +
> + /*
> + * A bitmap is maintained to teack the pages that are poisoned. Each
^track?
> + * page is represented by a bit. Allocation size in bytes is
> + * determined by shifting the device memory size by PAGE_SHIFT to
> + * determine the number of pages; and further shifted by 3 as each
> + * byte could track 8 pages.
> + */
> + nvdev->mem_prop.pfn_bitmap
> + = vzalloc(nvdev->mem_prop.mem_length >> (PAGE_SHIFT + 3));
> +
> + return 0;
> }
>
> static int nvgpu_vfio_pci_probe(struct pci_dev *pdev,
> @@ -224,6 +326,8 @@ static void nvgpu_vfio_pci_remove(struct pci_dev *pdev)
> struct nvgpu_vfio_pci_core_device *nvdev = nvgpu_drvdata(pdev);
> struct vfio_pci_core_device *vdev = &nvdev->core_device;
>
> + vfree(nvdev->mem_prop.pfn_bitmap);
> +
> vfio_pci_core_unregister_device(vdev);
> vfio_put_device(&vdev->vdev);
> }
