lkml.org 
[lkml]   [2020]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/4] vdpa: introduce config op to get valid iova range
From
Date

On 2020/8/6 下午8:29, Michael S. Tsirkin wrote:
> On Thu, Aug 06, 2020 at 03:03:55PM +0300, Eli Cohen wrote:
>> On Wed, Aug 05, 2020 at 08:51:56AM -0400, Michael S. Tsirkin wrote:
>>> On Wed, Jun 17, 2020 at 11:29:44AM +0800, Jason Wang wrote:
>>>> This patch introduce a config op to get valid iova range from the vDPA
>>>> device.
>>>>
>>>> Signed-off-by: Jason Wang<jasowang@redhat.com>
>>>> ---
>>>> include/linux/vdpa.h | 14 ++++++++++++++
>>>> 1 file changed, 14 insertions(+)
>>>>
>>>> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
>>>> index 239db794357c..b7633ed2500c 100644
>>>> --- a/include/linux/vdpa.h
>>>> +++ b/include/linux/vdpa.h
>>>> @@ -41,6 +41,16 @@ struct vdpa_device {
>>>> unsigned int index;
>>>> };
>>>>
>>>> +/**
>>>> + * vDPA IOVA range - the IOVA range support by the device
>>>> + * @start: start of the IOVA range
>>>> + * @end: end of the IOVA range
>>>> + */
>>>> +struct vdpa_iova_range {
>>>> + u64 start;
>>>> + u64 end;
>>>> +};
>>>> +
>>> This is ambiguous. Is end in the range or just behind it?
>>> How about first/last?
>> It is customary in the kernel to use start-end where end corresponds to
>> the byte following the last in the range. See struct vm_area_struct
>> vm_start and vm_end fields
> Exactly my point:
>
> include/linux/mm_types.h: unsigned long vm_end; /* The first byte after our end address
>
> in this case Jason wants it to be the last byte, not one behind.


Ok, I somehow recall the reason :)

See:

struct iommu_domain_geometry {
    dma_addr_t aperture_start; /* First address that can be mapped    */
    dma_addr_t aperture_end;   /* Last address that can be mapped     */
    bool force_aperture;       /* DMA only allowed in mappable range? */
};


So what I proposed here is to be consistent with it.

Thanks


>
>

\
 
 \ /
  Last update: 2020-08-07 05:23    [W:0.067 / U:0.276 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site