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SubjectRe: [PATCH] vhost: introduce vDPA based backend
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On 2020/2/5 下午1:31, Michael S. Tsirkin wrote:
> On Wed, Feb 05, 2020 at 11:12:21AM +0800, Jason Wang wrote:
>> On 2020/2/5 上午10:05, Tiwei Bie wrote:
>>> On Tue, Feb 04, 2020 at 02:46:16PM +0800, Jason Wang wrote:
>>>> On 2020/2/4 下午2:01, Michael S. Tsirkin wrote:
>>>>> On Tue, Feb 04, 2020 at 11:30:11AM +0800, Jason Wang wrote:
>>>>>> 5) generate diffs of memory table and using IOMMU API to setup the dma
>>>>>> mapping in this method
>>>>> Frankly I think that's a bunch of work. Why not a MAP/UNMAP interface?
>>>>>
>>>> Sure, so that basically VHOST_IOTLB_UPDATE/INVALIDATE I think?
>>> Do you mean we let userspace to only use VHOST_IOTLB_UPDATE/INVALIDATE
>>> to do the DMA mapping in vhost-vdpa case? When vIOMMU isn't available,
>>> userspace will set msg->iova to GPA, otherwise userspace will set
>>> msg->iova to GIOVA, and vhost-vdpa module will get HPA from msg->uaddr?
>>>
>>> Thanks,
>>> Tiwei
>> I think so. Michael, do you think this makes sense?
>>
>> Thanks
> to make sure, could you post the suggested argument format for
> these ioctls?
>

It's the existed uapi:

/* no alignment requirement */
struct vhost_iotlb_msg {
    __u64 iova;
    __u64 size;
    __u64 uaddr;
#define VHOST_ACCESS_RO      0x1
#define VHOST_ACCESS_WO      0x2
#define VHOST_ACCESS_RW      0x3
    __u8 perm;
#define VHOST_IOTLB_MISS           1
#define VHOST_IOTLB_UPDATE         2
#define VHOST_IOTLB_INVALIDATE     3
#define VHOST_IOTLB_ACCESS_FAIL    4
    __u8 type;
};

#define VHOST_IOTLB_MSG 0x1
#define VHOST_IOTLB_MSG_V2 0x2

struct vhost_msg {
    int type;
    union {
        struct vhost_iotlb_msg iotlb;
        __u8 padding[64];
    };
};

struct vhost_msg_v2 {
    __u32 type;
    __u32 reserved;
    union {
        struct vhost_iotlb_msg iotlb;
        __u8 padding[64];
    };
};

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