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

[Thomas Monjalon <thomas@monjalon.net>]

10/07/2019 14:35, Burakov, Anatoly:
> 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.

So we can ignore this issue.