Re: [Qemu-devel] [RFC PATCH v2 11/13] spapr_pci_vfio: Enable DDW

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 08/26/2014 05:19 PM, David Gibson wrote:
> On Fri, Aug 15, 2014 at 08:12:33PM +1000, Alexey Kardashevskiy wrote:
>> This implements DDW for VFIO. Host kernel support is required for this.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> Changes:
>> v2:
>> * remove()/reset() callbacks use spapr_pci's ones
>> ---
>>  hw/ppc/spapr_pci_vfio.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 86 insertions(+)
>>
>> diff --git a/hw/ppc/spapr_pci_vfio.c b/hw/ppc/spapr_pci_vfio.c
>> index 11b4272..79df716 100644
>> --- a/hw/ppc/spapr_pci_vfio.c
>> +++ b/hw/ppc/spapr_pci_vfio.c
>> @@ -71,6 +71,88 @@ static void spapr_phb_vfio_finish_realize(sPAPRPHBState *sphb, Error **errp)
>>                                  spapr_tce_get_iommu(tcet));
>>  
>>      object_unref(OBJECT(tcet));
>> +
>> +    if (sphb->ddw_enabled) {
>> +        sphb->ddw_enabled = !!(info.flags & VFIO_IOMMU_SPAPR_TCE_FLAG_DDW);
> 
> This overrides an explicit ddw= set by the user, which is a bit
> counter-intuitive.


For the user it is rather "try ddw when available" than "do ddw". This was
suggested by Alex Graf or I misunderstood his suggestion :)



> 
>> +    }
>> +}
>> +
>> +static int spapr_pci_vfio_ddw_query(sPAPRPHBState *sphb,
>> +                                    uint32_t *windows_available,
>> +                                    uint32_t *page_size_mask)
>> +{
>> +    sPAPRPHBVFIOState *svphb = SPAPR_PCI_VFIO_HOST_BRIDGE(sphb);
>> +    struct vfio_iommu_spapr_tce_query query = { .argsz = sizeof(query) };
>> +    int ret;
>> +
>> +    ret = vfio_container_ioctl(&sphb->iommu_as, svphb->iommugroupid,
>> +                               VFIO_IOMMU_SPAPR_TCE_QUERY, &query);
>> +    if (ret) {
>> +        return ret;
>> +    }
>> +
>> +    *windows_available = query.windows_available;
>> +    *page_size_mask = query.page_size_mask;
>> +
>> +    return ret;
>> +}
>> +
>> +static int spapr_pci_vfio_ddw_create(sPAPRPHBState *sphb, uint32_t page_shift,
>> +                                     uint32_t window_shift, uint32_t liobn,
>> +                                     sPAPRTCETable **ptcet)
>> +{
>> +    sPAPRPHBVFIOState *svphb = SPAPR_PCI_VFIO_HOST_BRIDGE(sphb);
>> +    struct vfio_iommu_spapr_tce_create create = {
>> +        .argsz = sizeof(create),
>> +        .page_shift = page_shift,
>> +        .window_shift = window_shift,
>> +        .start_addr = 0
>> +    };
>> +    int ret;
>> +
>> +    ret = vfio_container_ioctl(&sphb->iommu_as, svphb->iommugroupid,
>> +                               VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
>> +    if (ret) {
>> +        return ret;
>> +    }
>> +
>> +    *ptcet = spapr_tce_new_table(DEVICE(sphb), liobn,
>> +                                 create.start_addr, page_shift,
>> +                                 1ULL << (window_shift - page_shift),
>> +                                 true);
>> +    memory_region_add_subregion(&sphb->iommu_root, (*ptcet)->bus_offset,
>> +                                spapr_tce_get_iommu(*ptcet));
>> +
>> +    return ret;
>> +}
>> +
>> +static int spapr_pci_vfio_ddw_remove(sPAPRPHBState *sphb, sPAPRTCETable *tcet)
>> +{
>> +    sPAPRPHBVFIOState *svphb = SPAPR_PCI_VFIO_HOST_BRIDGE(sphb);
>> +    struct vfio_iommu_spapr_tce_remove remove = {
>> +        .argsz = sizeof(remove),
>> +        .start_addr = tcet->bus_offset
>> +    };
>> +    int ret;
>> +
>> +    spapr_pci_ddw_remove(sphb, tcet);
>> +    ret = vfio_container_ioctl(&sphb->iommu_as, svphb->iommugroupid,
>> +                               VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
>> +
>> +    return ret;
>> +}
>> +
>> +static int spapr_pci_vfio_ddw_reset(sPAPRPHBState *sphb)
>> +{
>> +    sPAPRPHBVFIOState *svphb = SPAPR_PCI_VFIO_HOST_BRIDGE(sphb);
>> +    struct vfio_iommu_spapr_tce_reset reset = { .argsz = sizeof(reset) };
>> +    int ret;
>> +
>> +    spapr_pci_ddw_reset(sphb);
>> +    ret = vfio_container_ioctl(&sphb->iommu_as, svphb->iommugroupid,
>> +                               VFIO_IOMMU_SPAPR_TCE_RESET, &reset);
> 
> Unlike the non-VFIO version, this doesn't appear to reset ddw_num.
> 
> Also, there isn't call to explicitly call DDW reset on system reset.
> Is that handled in kernel by the overall VFIO reset?


"[RFC PATCH v2 09/13] spapr_pci_vfio: Call spapr_pci::reset on reset"
effectively enables spapr_phb_reset() as a reset handler for VFIO PHB and
that function does spc->ddw_reset(). This was the real trigger-reason for
the 09/13 patch.


>> +    return ret;
>>  }
>>  
>>  static void spapr_phb_vfio_class_init(ObjectClass *klass, void *data)
>> @@ -80,6 +162,10 @@ static void spapr_phb_vfio_class_init(ObjectClass *klass, void *data)
>>  
>>      dc->props = spapr_phb_vfio_properties;
>>      spc->finish_realize = spapr_phb_vfio_finish_realize;
>> +    spc->ddw_query = spapr_pci_vfio_ddw_query;
>> +    spc->ddw_create = spapr_pci_vfio_ddw_create;
>> +    spc->ddw_remove = spapr_pci_vfio_ddw_remove;
>> +    spc->ddw_reset = spapr_pci_vfio_ddw_reset;
>>  }
>>  
>>  static const TypeInfo spapr_phb_vfio_info = {
> 


-- 
Alexey