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Message-ID: <ce21ef1e-5ffd-586c-0925-d3a59eb0c30d@redhat.com>
Date: Fri, 13 Nov 2020 17:12:14 +0100
From: Auger Eric <eric.auger@...hat.com>
To: Zenghui Yu <yuzenghui@...wei.com>, eric.auger.pro@...il.com,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, joro@...tes.org,
alex.williamson@...hat.com, jacob.jun.pan@...ux.intel.com,
yi.l.liu@...el.com, robin.murphy@....com
Subject: Re: [PATCH v10 04/11] vfio/pci: Add VFIO_REGION_TYPE_NESTED region
type
Hi Zenghui,
On 9/24/20 10:23 AM, Zenghui Yu wrote:
> Hi Eric,
>
> On 2020/3/21 0:19, Eric Auger wrote:
>> 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@...hat.com>
>
> [...]
>
>> 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;
>
> What's the reason to use 'u8'? It doesn't match the type of header, nor
> the type of ring buffer.
actually it matches
u8 *pci_config_map;
u8 *vconfig;
fault_pages is the va of the ring buffer. In the header, offset is the
offset of the ring wrt start of the region.
>
>> + 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;
>> +};
>
> This is not used by this patch (and the whole series).
removed
>
>> +
>> +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) {
>
> Maybe
>
> new_tail >= header->nb_entries ?
sure
Thanks
Eric
>
>> + 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;
>
>
> Thanks,
> Zenghui
>
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