Re: [dpdk-dev] [PATCH] vfio: retry creating sPAPR DMA window

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

On 10-Jul-19 1:17 PM, Thomas Monjalon wrote:
> 10/07/2019 12:32, Burakov, Anatoly:
>> On 07-Jun-19 3:28 AM, Takeshi Yoshimura wrote:
>>> sPAPR allows only page_shift from VFIO_IOMMU_SPAPR_TCE_GET_INFO ioctl.
>>> However, Linux 4.17 or before returns incorrect page_shift for Power9.
>>> I added the code for retrying creation of sPAPR DMA window.
>>>
>>> Signed-off-by: Takeshi Yoshimura <tyos@jp.ibm.com>
>>> ---
>>>    lib/librte_eal/linux/eal/eal_vfio.c | 26 +++++++++++++++++++++++---
>>>    1 file changed, 23 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/lib/librte_eal/linux/eal/eal_vfio.c b/lib/librte_eal/linux/eal/eal_vfio.c
>>> index 6892a2c14..f16c5c3c0 100644
>>> --- a/lib/librte_eal/linux/eal/eal_vfio.c
>>> +++ b/lib/librte_eal/linux/eal/eal_vfio.c
>>> @@ -1448,9 +1448,29 @@ vfio_spapr_create_new_dma_window(int vfio_container_fd,
>>>    	/* create new DMA window */
>>>    	ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_CREATE, create);
>>>    	if (ret) {
>>> -		RTE_LOG(ERR, EAL, "  cannot create new DMA window, "
>>> -				"error %i (%s)\n", errno, strerror(errno));
>>> -		return -1;
>>> +		/* try possible page_shift and levels for workaround */
>>> +		uint32_t levels;
>>> +
>>> +		for (levels = 1; levels <= info.ddw.levels; levels++) {
>>> +			uint32_t pgsizes = info.ddw.pgsizes;
>>
>> +CC POWER maintainer from MAINTAINERS file.
>>
>> This is failing compilation on some older distros (Fedora 20, Ubuntu 14.04):
>>
>>
>> /root/dpdk/lib/librte_eal/linux/eal/eal_vfio.c: In function
>> ‘vfio_spapr_create_new_dma_window’:
>> /root/dpdk/lib/librte_eal/linux/eal/eal_vfio.c:1451:34: error: ‘struct
>> vfio_iommu_spapr_tce_info’ has no member named ‘ddw’
>> for (levels = 1; levels <= info.ddw.levels; levels++) {
>> ^
>> /root/dpdk/lib/librte_eal/linux/eal/eal_vfio.c:1452:27: error: ‘struct
>> vfio_iommu_spapr_tce_info’ has no member named ‘ddw’
>> uint32_t pgsizes = info.ddw.pgsizes;
>> ^
>> /root/dpdk/lib/librte_eal/linux/eal/eal_vfio.c: At top level:
>> cc1: error: unrecognized command line option
>> "-Wno-address-of-packed-member" [-Werror]
>> cc1: all warnings being treated as errors
>> make[7]: *** [eal_vfio.o] Error 1
>> make[7]: *** Waiting for unfinished jobs....
>> make[6]: *** [eal] Error 2
>> make[5]: *** [linux] Error 2
>> make[4]: *** [librte_eal] Error 2
>> make[3]: *** [lib] Error 2
>> make[2]: *** [all] Error 2
>> make[1]: *** [pre_install] Error 2
>> make: *** [install] Error 2
>>
>>
>> Looking at the eal_vfio.h we are handling case of missing sPAPR info/ddw
>> structures, but this isn't simply a case of a missing struct; rather it
>> is an issue of differing definitions between what recent kernels have,
>> and what older kernels had.
>>
>> @Thomas Do we still support these older distros?
> 
> If the kernel is not maintained, we don't support it.
> For most distros, Linux < 3.16 is not maintained.
> 

This is on kernel 3.13 (Ubuntu 14.04 LTS which according to Canonical's 
published schedule [1] has stopped receiving even maintenance updates, 
and is only updated for select customers). It was never an LTS kernel to 
begin with, i think.

[1] https://ubuntu.com/about/release-cycle

-- 
Thanks,
Anatoly