Re: [Qemu-devel] [PATCH] hw/vfio/common: Refactor container initialization

[Greg Kurz <groug@kaod.org>]

On Mon, 14 Jan 2019 09:34:12 +0100
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Alexey,
> 
> On 1/14/19 7:32 AM, Alexey Kardashevskiy wrote:
> > 
> > 
> > On 12/01/2019 03:45, Eric Auger wrote:  
> >> In vfio_connect_container() the code that selects the
> >> iommu type can benefit from helpers such as
> >> vfio_iommu_get_type() and vfio_init_container(). As
> >> a result we end up with a switch/case on the iommu type
> >> that makes the code a little bit more readable and ready
> >> for addition of new iommu types. Also ioctl's get called
> >> once per iommu_type.  
> > 
> > 
> > ioctl(VFIO_SET_IOMMU) is called twice for a reason - on sPAPR, the IOMMU
> > subdriver is always capable of v1 and v2 but the running platform is not
> > - powernv supports v2, pseries does not but there is no way telling this
> > until an IOMMU group is added to a container. So the existing code tries
> > v2, if that fails, it tries v1:
> > https://git.qemu.org/?p=qemu.git;a=commitdiff;h=c6e7958eb76ed267f7  
> 
> I definitively missed that point. I will add this behavior in
> vfio_init_container then.
> 

So did I :(

Please drop my R-b tag then and I'll review the next version.

Cheers,

--
Greg

> Thanks!
> 
> Eric
> > 
> > 
> >   
> >>
> >> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> >> Reviewed-by: Greg Kurz <groug@kaod.org>
> >>
> >> ---
> >>
> >> v2 -> v3:
> >> - originally submitted in [RFC v2 00/28] vSMMUv3/pSMMUv3
> >>   2 stage VFIO integration
> >> - remove "nested only is selected if requested by @force_nested"
> >> - added Greg's R-b
> >> ---
> >>  hw/vfio/common.c | 101 ++++++++++++++++++++++++++++++-----------------
> >>  1 file changed, 64 insertions(+), 37 deletions(-)
> >>
> >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> >> index 7c185e5a2e..8535bfe66f 100644
> >> --- a/hw/vfio/common.c
> >> +++ b/hw/vfio/common.c
> >> @@ -1036,12 +1036,57 @@ static void vfio_put_address_space(VFIOAddressSpace *space)
> >>      }
> >>  }
> >>  
> >> +/*
> >> + * vfio_iommu_get_type - selects the richest iommu_type (v2 first)
> >> + */
> >> +static int vfio_iommu_get_type(VFIOContainer *container,
> >> +                               Error **errp)
> >> +{
> >> +    int fd = container->fd;
> >> +
> >> +    if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU)) {
> >> +        return VFIO_TYPE1v2_IOMMU;
> >> +    } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU)) {
> >> +        return VFIO_TYPE1_IOMMU;
> >> +    } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU)) {
> >> +        return VFIO_SPAPR_TCE_v2_IOMMU;
> >> +    } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU)) {
> >> +        return VFIO_SPAPR_TCE_IOMMU;
> >> +    } else {
> >> +        error_setg(errp, "No available IOMMU models");
> >> +        return -EINVAL;
> >> +    }
> >> +}
> >> +
> >> +static int vfio_init_container(VFIOContainer *container, int group_fd,
> >> +                               int iommu_type, Error **errp)
> >> +{
> >> +    int ret;
> >> +
> >> +    ret = ioctl(group_fd, VFIO_GROUP_SET_CONTAINER, &container->fd);
> >> +    if (ret) {
> >> +        error_setg_errno(errp, errno, "failed to set group container");
> >> +        return -errno;
> >> +    }
> >> +
> >> +    ret = ioctl(container->fd, VFIO_SET_IOMMU, iommu_type);
> >> +    if (ret) {
> >> +        error_setg_errno(errp, errno, "failed to set iommu for container");
> >> +        return -errno;
> >> +    }
> >> +    container->iommu_type = iommu_type;
> >> +    return 0;
> >> +}
> >> +
> >>  static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
> >>                                    Error **errp)
> >>  {
> >>      VFIOContainer *container;
> >>      int ret, fd;
> >>      VFIOAddressSpace *space;
> >> +    int iommu_type;
> >> +    bool v2 = false;
> >> +
> >>  
> >>      space = vfio_get_address_space(as);
> >>  
> >> @@ -1101,23 +1146,20 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
> >>      container->fd = fd;
> >>      QLIST_INIT(&container->giommu_list);
> >>      QLIST_INIT(&container->hostwin_list);
> >> -    if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU) ||
> >> -        ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU)) {
> >> -        bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU);
> >> +
> >> +    iommu_type = vfio_iommu_get_type(container, errp);
> >> +    if (iommu_type < 0) {
> >> +            goto free_container_exit;
> >> +    }
> >> +
> >> +    switch (iommu_type) {
> >> +    case VFIO_TYPE1v2_IOMMU:
> >> +    case VFIO_TYPE1_IOMMU:
> >> +    {
> >>          struct vfio_iommu_type1_info info;
> >>  
> >> -        ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
> >> +        ret = vfio_init_container(container, group->fd, iommu_type, errp);
> >>          if (ret) {
> >> -            error_setg_errno(errp, errno, "failed to set group container");
> >> -            ret = -errno;
> >> -            goto free_container_exit;
> >> -        }
> >> -
> >> -        container->iommu_type = v2 ? VFIO_TYPE1v2_IOMMU : VFIO_TYPE1_IOMMU;
> >> -        ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
> >> -        if (ret) {
> >> -            error_setg_errno(errp, errno, "failed to set iommu for container");
> >> -            ret = -errno;
> >>              goto free_container_exit;
> >>          }
> >>  
> >> @@ -1137,28 +1179,16 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
> >>          }
> >>          vfio_host_win_add(container, 0, (hwaddr)-1, info.iova_pgsizes);
> >>          container->pgsizes = info.iova_pgsizes;
> >> -    } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU) ||
> >> -               ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU)) {
> >> +        break;
> >> +    }
> >> +    case VFIO_SPAPR_TCE_v2_IOMMU:
> >> +        v2 = true;
> >> +    case VFIO_SPAPR_TCE_IOMMU:
> >> +    {
> >>          struct vfio_iommu_spapr_tce_info info;
> >> -        bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU);
> >>  
> >> -        ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
> >> +        ret = vfio_init_container(container, group->fd, iommu_type, errp);
> >>          if (ret) {
> >> -            error_setg_errno(errp, errno, "failed to set group container");
> >> -            ret = -errno;
> >> -            goto free_container_exit;
> >> -        }
> >> -        container->iommu_type =
> >> -            v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU;
> >> -        ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
> >> -        if (ret) {
> >> -            container->iommu_type = VFIO_SPAPR_TCE_IOMMU;
> >> -            v2 = false;
> >> -            ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
> >> -        }
> >> -        if (ret) {
> >> -            error_setg_errno(errp, errno, "failed to set iommu for container");
> >> -            ret = -errno;
> >>              goto free_container_exit;
> >>          }
> >>  
> >> @@ -1222,10 +1252,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
> >>                                info.dma32_window_size - 1,
> >>                                0x1000);
> >>          }
> >> -    } else {
> >> -        error_setg(errp, "No available IOMMU models");
> >> -        ret = -EINVAL;
> >> -        goto free_container_exit;
> >> +    }
> >>      }
> >>  
> >>      vfio_kvm_device_add_group(group);
> >>  
> >