Re: [dpdk-dev] [PATCH v2 2/2] vhost: enable IOMMU for async vhost

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Friday, September 24, 2021 3:14 PM
> To: Xia, Chenbo <chenbo.xia@intel.com>; Hu, Jiayu <jiayu.hu@intel.com>; Ding,
> Xuan <xuan.ding@intel.com>; dev@dpdk.org; Burakov, Anatoly
> <anatoly.burakov@intel.com>
> Cc: Jiang, Cheng1 <cheng1.jiang@intel.com>; Richardson, Bruce
> <bruce.richardson@intel.com>; Pai G, Sunil <sunil.pai.g@intel.com>; Wang,
> Yinan <yinan.wang@intel.com>; Yang, YvonneX <yvonnex.yang@intel.com>
> Subject: Re: [PATCH v2 2/2] vhost: enable IOMMU for async vhost
> 
> 
> 
> On 9/24/21 03:53, Xia, Chenbo wrote:
> >> -----Original Message-----
> >> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> >> Sent: Thursday, September 23, 2021 10:56 PM
> >> To: Hu, Jiayu <jiayu.hu@intel.com>; Ding, Xuan <xuan.ding@intel.com>;
> >> dev@dpdk.org; Burakov, Anatoly <anatoly.burakov@intel.com>; Xia, Chenbo
> >> <chenbo.xia@intel.com>
> >> Cc: Jiang, Cheng1 <cheng1.jiang@intel.com>; Richardson, Bruce
> >> <bruce.richardson@intel.com>; Pai G, Sunil <sunil.pai.g@intel.com>; Wang,
> >> Yinan <yinan.wang@intel.com>; Yang, YvonneX <yvonnex.yang@intel.com>
> >> Subject: Re: [PATCH v2 2/2] vhost: enable IOMMU for async vhost
> >>
> >>
> >>
> >> On 9/23/21 16:39, Hu, Jiayu wrote:
> >>> Hi Xuan,
> >>>
> >>>> -----Original Message-----
> >>>> From: Ding, Xuan <xuan.ding@intel.com>
> >>>> Sent: Friday, September 17, 2021 1:26 PM
> >>>> To: dev@dpdk.org; Burakov, Anatoly <anatoly.burakov@intel.com>;
> >>>> maxime.coquelin@redhat.com; Xia, Chenbo <chenbo.xia@intel.com>
> >>>> Cc: Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> <cheng1.jiang@intel.com>;
> >>>> Richardson, Bruce <bruce.richardson@intel.com>; Pai G, Sunil
> >>>> <sunil.pai.g@intel.com>; Wang, Yinan <yinan.wang@intel.com>; Yang,
> >>>> YvonneX <yvonnex.yang@intel.com>; Ding, Xuan <xuan.ding@intel.com>
> >>>> Subject: [PATCH v2 2/2] vhost: enable IOMMU for async vhost
> >>>>
> >>>> The use of IOMMU has many advantages, such as isolation and address
> >>>> translation. This patch extends the capbility of DMA engine to use IOMMU
> if
> >>>> the DMA engine is bound to vfio.
> >>>>
> >>>> When set memory table, the guest memory will be mapped into the default
> >>>> container of DPDK.
> >>>>
> >>>> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> >>>> ---
> >>>>    lib/vhost/rte_vhost.h  |  1 +
> >>>>    lib/vhost/vhost_user.c | 57
> >>>> +++++++++++++++++++++++++++++++++++++++++-
> >>>>    2 files changed, 57 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h index
> >>>> 8d875e9322..e0537249f3 100644
> >>>> --- a/lib/vhost/rte_vhost.h
> >>>> +++ b/lib/vhost/rte_vhost.h
> >>>> @@ -127,6 +127,7 @@ struct rte_vhost_mem_region {
> >>>>    	void	 *mmap_addr;
> >>>>    	uint64_t mmap_size;
> >>>>    	int fd;
> >>>> +	uint64_t dma_map_success;
> >>>
> >>> How about using bool for dma_map_success?
> >>
> >> The bigger problem here is that you are breaking the ABI.
> >
> > Maybe this kind of driver-facing structs/functions should be removed
> > from ABI, since we are refactoring DPDK ABI recently.
> 
> It has actually been exposed for SPDK, we cannot just remove it from
> API.

'exposed' does not mean it has to be ABI. Like 'driver_sdk_headers' in
ethdev lib, those headers can be exposed but do not include ABI. I see
SPDK is using that for building its lib. Not sure in this case, the SPDK
Vhost lib should be considered as application.

Thanks,
Chenbo 

> 
> Maxime
> 
> > /Chenbo
> >
> >>
> >>>>    };
> >>>>
> >>>>    /**
> >