Re: [dpdk-dev] [PATCH v2] vfio: allow secondary process to query IOMMU type

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 19-Jan-19 3:23 AM, Wang, Xiao W wrote:
> Hi Anatoly,
> 
>> -----Original Message-----
>> From: Burakov, Anatoly
>> Sent: Friday, January 18, 2019 6:25 PM
>> To: dev@dpdk.org
>> Cc: Wang, Xiao W <xiao.w.wang@intel.com>; Zhang, Qi Z
>> <qi.z.zhang@intel.com>; qingfu.cqf@alibaba-inc.com; thomas@monjalon.net;
>> Stojaczyk, Dariusz <dariusz.stojaczyk@intel.com>; stable@dpdk.org
>> Subject: [PATCH v2] vfio: allow secondary process to query IOMMU type
>>
>> It is only possible to know IOMMU type of a given VFIO container
>> by attempting to initialize it. Since secondary process never
>> attempts to set up VFIO container itself (because they're shared
>> between primary and secondary), it never knows which IOMMU type
>> the container is using, and never sets up the appropriate config
>> structures. This results in inability to perform DMA mappings in
>> secondary process.
>>
>> Fix this by allowing secondary process to query IOMMU type of
>> primary's default container at device initialization.
>>
>> Note that this fix is assuming we're only interested in default
>> container.
>>
>> Bugzilla ID: 174
>>
>> Fixes: 6bcb7c95fe14 ("vfio: share default container in multi-process")
>> Cc: dariusz.stojaczyk@intel.com
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
>> ---
>>
>> Notes:
>>      v2:
>>      - Check if we found our IOMMU type within list of IOMMU types
>>      - Don't request new default container fd as this should have
>>        been done during rte_vfio_enable()
>>
>>   lib/librte_eal/linuxapp/eal/eal_vfio.c        | 88 +++++++++++++++++++
>>   lib/librte_eal/linuxapp/eal/eal_vfio.h        | 12 ++-
>>   .../linuxapp/eal/eal_vfio_mp_sync.c           | 16 ++++
>>   3 files changed, 115 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c
>> b/lib/librte_eal/linuxapp/eal/eal_vfio.c
>> index 72cc65151..c821e8382 100644
>> --- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
>> +++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
>> @@ -549,6 +549,65 @@ vfio_mem_event_callback(enum rte_mem_event
>> type, const void *addr, size_t len,
>>   	}
>>   }
>>
>> +static int
>> +vfio_sync_default_container(void)
>> +{
>> +	struct rte_mp_msg mp_req, *mp_rep;
>> +	struct rte_mp_reply mp_reply;
>> +	struct timespec ts = {.tv_sec = 5, .tv_nsec = 0};
>> +	struct vfio_mp_param *p = (struct vfio_mp_param *)mp_req.param;
>> +	int iommu_type_id;
>> +	unsigned int i;
>> +
>> +	/* cannot be called from primary */
>> +	if (rte_eal_process_type() != RTE_PROC_SECONDARY)
>> +		return -1;
>> +
>> +	/* default container fd should have been opened in rte_vfio_enable()
>> */
>> +	if (!default_vfio_cfg->vfio_enabled ||
>> +			default_vfio_cfg->vfio_container_fd < 0) {
>> +		RTE_LOG(ERR, EAL, "VFIO support is not initialized\n");
>> +		return -1;
>> +	}
>> +
>> +	/* find default container's IOMMU type */
>> +	p->req = SOCKET_REQ_IOMMU_TYPE;
> 
> Since this function is to sync IOMMU type for the default container, should we make the req type as
> SOCKET_REQ_DEFAULT_IOMMU_TYPE?

Hi,

Sure, that can be done. However, i don't think it warrants a respin 
unless there's more important stuff to fix also. This patch is a 
stop-gap, and this stuff will be rewritten for 19.05, so getting this 
right is not that important :).

> 
> BRs,
> Xiao
> 


-- 
Thanks,
Anatoly