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SubjectRe: [PATCH V2 9/9] vhost: do not return -EAGIAN for non blocking invalidation too early
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On 2019/7/31 下午5:59, Stefano Garzarella wrote:
> A little typo in the title: s/EAGIAN/EAGAIN
>
> Thanks,
> Stefano


Right, will fix if need respin or Michael can help to fix.

Thanks


>
> On Wed, Jul 31, 2019 at 04:46:55AM -0400, Jason Wang wrote:
>> Instead of returning -EAGAIN unconditionally, we'd better do that only
>> we're sure the range is overlapped with the metadata area.
>>
>> Reported-by: Jason Gunthorpe <jgg@ziepe.ca>
>> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> drivers/vhost/vhost.c | 32 +++++++++++++++++++-------------
>> 1 file changed, 19 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>> index fc2da8a0c671..96c6aeb1871f 100644
>> --- a/drivers/vhost/vhost.c
>> +++ b/drivers/vhost/vhost.c
>> @@ -399,16 +399,19 @@ static void inline vhost_vq_sync_access(struct vhost_virtqueue *vq)
>> smp_mb();
>> }
>>
>> -static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
>> - int index,
>> - unsigned long start,
>> - unsigned long end)
>> +static int vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
>> + int index,
>> + unsigned long start,
>> + unsigned long end,
>> + bool blockable)
>> {
>> struct vhost_uaddr *uaddr = &vq->uaddrs[index];
>> struct vhost_map *map;
>>
>> if (!vhost_map_range_overlap(uaddr, start, end))
>> - return;
>> + return 0;
>> + else if (!blockable)
>> + return -EAGAIN;
>>
>> spin_lock(&vq->mmu_lock);
>> ++vq->invalidate_count;
>> @@ -423,6 +426,8 @@ static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
>> vhost_set_map_dirty(vq, map, index);
>> vhost_map_unprefetch(map);
>> }
>> +
>> + return 0;
>> }
>>
>> static void vhost_invalidate_vq_end(struct vhost_virtqueue *vq,
>> @@ -443,18 +448,19 @@ static int vhost_invalidate_range_start(struct mmu_notifier *mn,
>> {
>> struct vhost_dev *dev = container_of(mn, struct vhost_dev,
>> mmu_notifier);
>> - int i, j;
>> -
>> - if (!mmu_notifier_range_blockable(range))
>> - return -EAGAIN;
>> + bool blockable = mmu_notifier_range_blockable(range);
>> + int i, j, ret;
>>
>> for (i = 0; i < dev->nvqs; i++) {
>> struct vhost_virtqueue *vq = dev->vqs[i];
>>
>> - for (j = 0; j < VHOST_NUM_ADDRS; j++)
>> - vhost_invalidate_vq_start(vq, j,
>> - range->start,
>> - range->end);
>> + for (j = 0; j < VHOST_NUM_ADDRS; j++) {
>> + ret = vhost_invalidate_vq_start(vq, j,
>> + range->start,
>> + range->end, blockable);
>> + if (ret)
>> + return ret;
>> + }
>> }
>>
>> return 0;
>> --
>> 2.18.1
>>

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