Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support

2017-07-05 Thread Paolo Bonzini 


On 05/07/2017 08:23, Fam Zheng wrote:
>>  req->vq = vq;
>>  req->dev = s;
>> -qemu_sglist_init(>qsgl, DEVICE(s), 8, _space_memory);
>> +qemu_sglist_init(>qsgl, DEVICE(s), 8, vdev->dma_as);
> Not related to this patch, but is our vIOMMU iotlb implementation safe for 
> data
> plane (both virtio-blk and virtio-scsi)? There we don't have BQL to 
> synchronize
> between IOVA lookup and update, which means threads can race when accessing 
> the
> iotlb GHashTable.
> 
> Did I overlook a synchronization mechanism? Or is it missing? Paolo, MST?

I think it's missing.  One way to fix it could be to finish the
MemoryRegionCache work and have an IOMMU->virtio notifier, similar to
how vhost works.

Paolo

Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support

2017-07-05 Thread Fam Zheng 
On Tue, 07/04 20:21, Jason Wang wrote:
> After converting to use DMA api for virtio devices, we should use
> dma_as instead of address_space_memory. Otherwise it won't work if
> IOMMU is enabled.
> 
> Fixes: commit 8607f5c3072c ("virtio: convert to use DMA api")
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Jason Wang 
> ---
>  hw/scsi/virtio-scsi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index f46f06d..d076fe7 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -43,12 +43,13 @@ static inline SCSIDevice 
> *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
>  
>  void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
>  {
> +VirtIODevice *vdev = VIRTIO_DEVICE(s);
>  const size_t zero_skip =
>  offsetof(VirtIOSCSIReq, resp_iov) + sizeof(req->resp_iov);
>  
>  req->vq = vq;
>  req->dev = s;
> -qemu_sglist_init(>qsgl, DEVICE(s), 8, _space_memory);
> +qemu_sglist_init(>qsgl, DEVICE(s), 8, vdev->dma_as);

Not related to this patch, but is our vIOMMU iotlb implementation safe for data
plane (both virtio-blk and virtio-scsi)? There we don't have BQL to synchronize
between IOVA lookup and update, which means threads can race when accessing the
iotlb GHashTable.

Did I overlook a synchronization mechanism? Or is it missing? Paolo, MST?

Fam

>  qemu_iovec_init(>resp_iov, 1);
>  memset((uint8_t *)req + zero_skip, 0, sizeof(*req) - zero_skip);
>  }
> -- 
> 2.7.4
> 
>

Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support

2017-07-04 Thread Wei Xu 
On Tue, Jul 04, 2017 at 08:21:06PM +0800, Jason Wang wrote:
> After converting to use DMA api for virtio devices, we should use
> dma_as instead of address_space_memory. Otherwise it won't work if
> IOMMU is enabled.
> 
> Fixes: commit 8607f5c3072c ("virtio: convert to use DMA api")
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Jason Wang 
> ---
>  hw/scsi/virtio-scsi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index f46f06d..d076fe7 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -43,12 +43,13 @@ static inline SCSIDevice 
> *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
>  
>  void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
>  {
> +VirtIODevice *vdev = VIRTIO_DEVICE(s);
>  const size_t zero_skip =
>  offsetof(VirtIOSCSIReq, resp_iov) + sizeof(req->resp_iov);
>  
>  req->vq = vq;
>  req->dev = s;
> -qemu_sglist_init(>qsgl, DEVICE(s), 8, _space_memory);
> +qemu_sglist_init(>qsgl, DEVICE(s), 8, vdev->dma_as);
>  qemu_iovec_init(>resp_iov, 1);
>  memset((uint8_t *)req + zero_skip, 0, sizeof(*req) - zero_skip);
>  }

Reviewed-by: Wei Xu 

> -- 
> 2.7.4
> 
>

Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support

2017-07-04 Thread Fam Zheng 
On Tue, 07/04 20:21, Jason Wang wrote:
> After converting to use DMA api for virtio devices, we should use
> dma_as instead of address_space_memory. Otherwise it won't work if
> IOMMU is enabled.
> 
> Fixes: commit 8607f5c3072c ("virtio: convert to use DMA api")
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Jason Wang 

Reviewed-by: Fam Zheng

[Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support

2017-07-04 Thread Jason Wang 
After converting to use DMA api for virtio devices, we should use
dma_as instead of address_space_memory. Otherwise it won't work if
IOMMU is enabled.

Fixes: commit 8607f5c3072c ("virtio: convert to use DMA api")
Cc: qemu-sta...@nongnu.org
Signed-off-by: Jason Wang 
---
 hw/scsi/virtio-scsi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index f46f06d..d076fe7 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -43,12 +43,13 @@ static inline SCSIDevice 
*virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
 
 void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
 {
+VirtIODevice *vdev = VIRTIO_DEVICE(s);
 const size_t zero_skip =
 offsetof(VirtIOSCSIReq, resp_iov) + sizeof(req->resp_iov);
 
 req->vq = vq;
 req->dev = s;
-qemu_sglist_init(>qsgl, DEVICE(s), 8, _space_memory);
+qemu_sglist_init(>qsgl, DEVICE(s), 8, vdev->dma_as);
 qemu_iovec_init(>resp_iov, 1);
 memset((uint8_t *)req + zero_skip, 0, sizeof(*req) - zero_skip);
 }
-- 
2.7.4