Re: [Qemu-ppc] [RFC PATCH qemu v3 2/4] vfio: Use different page size for different IOMMU types

[Alexey Kardashevskiy]

On 07/16/2015 04:26 AM, Alex Williamson wrote:
> On Tue, 2015-07-14 at 22:21 +1000, Alexey Kardashevskiy wrote:
> > The existing memory listener is called on RAM or PCI address space
> > which implies potentially different page size. Instead of guessing
> > what page size should be used, this replaces a single IOMMU memory
> > listener by two, one per supported IOMMU type; listener callbacks
> > call the existing helpers with a known page size.
> >
> > For now, Type1 uses qemu_real_host_page_mask, sPAPR uses the page size
> > from IOMMU.
> >
> > As memory_region_iommu_get_page_sizes() asserts on non-IOMMU regions,
> > this adds memory_region_is_iommu() to the SPAPR IOMMU listener to skip
> > non IOMMU regions (which is an MSIX window) which duplicates
> > vfio_listener_skipped_section() a bit.
> >
> > Signed-off-by: Alexey Kardashevskiy <address@hidden>
> > ---
> >   hw/vfio/common.c | 95 ++++++++++++++++++++++++++++++++++++++++++++------------
> >   1 file changed, 76 insertions(+), 19 deletions(-)
> >
> > diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> > index 85ee9b0..aad41e1 100644
> > --- a/hw/vfio/common.c
> > +++ b/hw/vfio/common.c
> > @@ -312,11 +312,11 @@ out:
> >       rcu_read_unlock();
> >   }
> >
> > -static void vfio_listener_region_add(MemoryListener *listener,
> > +static void vfio_listener_region_add(VFIOContainer *container,
> > +                                     hwaddr page_mask,
>
> Should memory_region_iommu_get_page_sizes() return a hwaddr?


I do not think so, memory.c uses uint64_t for masks.



> > +                                     MemoryListener *listener,
> >                                        MemoryRegionSection *section)
> >   {
> > -    VFIOContainer *container = container_of(listener, VFIOContainer,
> > -                                            iommu_data.type1.listener);
> >       hwaddr iova, end;
> >       Int128 llend;
> >       void *vaddr;
> > @@ -330,16 +330,16 @@ static void vfio_listener_region_add(MemoryListener 
> > *listener,
> >           return;
> >       }
> >
> > -    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) !=
> > -                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
> > +    if (unlikely((section->offset_within_address_space & ~page_mask) !=
> > +                 (section->offset_within_region & ~page_mask))) {
> >           error_report("%s received unaligned region", __func__);
> >           return;
> >       }
> >
> > -    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
> > +    iova = ROUND_UP(section->offset_within_address_space, ~page_mask + 1);
> >       llend = int128_make64(section->offset_within_address_space);
> >       llend = int128_add(llend, section->size);
> > -    llend = int128_and(llend, int128_exts64(TARGET_PAGE_MASK));
> > +    llend = int128_and(llend, int128_exts64(page_mask));
> >
> >       if (int128_ge(int128_make64(iova), llend)) {
> >           return;
> > @@ -416,11 +416,11 @@ static void vfio_listener_region_add(MemoryListener 
> > *listener,
> >       }
> >   }
> >
> > -static void vfio_listener_region_del(MemoryListener *listener,
> > +static void vfio_listener_region_del(VFIOContainer *container,
> > +                                     hwaddr page_mask,
> > +                                     MemoryListener *listener,
> >                                        MemoryRegionSection *section)
> >   {
> > -    VFIOContainer *container = container_of(listener, VFIOContainer,
> > -                                            iommu_data.type1.listener);
> >       hwaddr iova, end;
> >       int ret;
> >
> > @@ -432,8 +432,8 @@ static void vfio_listener_region_del(MemoryListener 
> > *listener,
> >           return;
> >       }
> >
> > -    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) !=
> > -                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
> > +    if (unlikely((section->offset_within_address_space & ~page_mask) !=
> > +                 (section->offset_within_region & ~page_mask))) {
> >           error_report("%s received unaligned region", __func__);
> >           return;
> >       }
> > @@ -459,9 +459,9 @@ static void vfio_listener_region_del(MemoryListener 
> > *listener,
> >            */
> >       }
> >
> > -    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
> > +    iova = ROUND_UP(section->offset_within_address_space, ~page_mask + 1);
> >       end = (section->offset_within_address_space + int128_get64(section->size)) 
> > &
> > -          TARGET_PAGE_MASK;
> > +          page_mask;
> >
> >       if (iova >= end) {
> >           return;
> > @@ -478,9 +478,66 @@ static void vfio_listener_region_del(MemoryListener 
> > *listener,
> >       }
> >   }
> >
> > -static const MemoryListener vfio_memory_listener = {
> > -    .region_add = vfio_listener_region_add,
> > -    .region_del = vfio_listener_region_del,
> > +static void vfio_type1_iommu_listener_region_add(MemoryListener *listener,
> > +                                                 MemoryRegionSection *section)
> > +{
> > +    VFIOContainer *container = container_of(listener, VFIOContainer,
> > +                                            iommu_data.type1.listener);
> > +
> > +    vfio_listener_region_add(container, qemu_real_host_page_mask, listener,
> > +                             section);
> > +}
> > +
> > +
> > +static void vfio_type1_iommu_listener_region_del(MemoryListener *listener,
> > +                                                 MemoryRegionSection *section)
> > +{
> > +    VFIOContainer *container = container_of(listener, VFIOContainer,
> > +                                            iommu_data.type1.listener);
> > +
> > +    vfio_listener_region_del(container, qemu_real_host_page_mask, listener,
> > +                             section);
> > +}
> > +
> > +static const MemoryListener vfio_type1_iommu_listener = {
> > +    .region_add = vfio_type1_iommu_listener_region_add,
> > +    .region_del = vfio_type1_iommu_listener_region_del,
> > +};
> > +
> > +static void vfio_spapr_iommu_listener_region_add(MemoryListener *listener,
> > +                                     MemoryRegionSection *section)
> > +{
> > +    VFIOContainer *container;
> > +    hwaddr page_mask;
> > +
> > +    if (!memory_region_is_iommu(section->mr)) {
> > +        return;
> > +    }
> > +    container = container_of(listener, VFIOContainer,
> > +                             iommu_data.type1.listener);
> > +    page_mask = ~(memory_region_iommu_get_page_sizes(section->mr) - 1);
> > +    vfio_listener_region_add(container, page_mask, listener, section);
> > +}
> > +
> > +
> > +static void vfio_spapr_iommu_listener_region_del(MemoryListener *listener,
> > +                                     MemoryRegionSection *section)
> > +{
> > +    VFIOContainer *container;
> > +    hwaddr page_mask;
> > +
> > +    if (!memory_region_is_iommu(section->mr)) {
> > +        return;
> > +    }
> > +    container = container_of(listener, VFIOContainer,
> > +                             iommu_data.type1.listener);
> > +    page_mask = ~(memory_region_iommu_get_page_sizes(section->mr) - 1);
> > +    vfio_listener_region_del(container, page_mask, listener, section);
> > +}
> > +
> > +static const MemoryListener vfio_spapr_iommu_listener = {
> > +    .region_add = vfio_spapr_iommu_listener_region_add,
> > +    .region_del = vfio_spapr_iommu_listener_region_del,
> >   };
>
>
> Rather than creating all these wrappers, why don't we create a structure
> that gives us callbacks we can use for a shared function?  If we had:
>
> struct VFIOMemoryListener {
>         struct MemoryListener listener;
>         bool (*filter)(MemoryRegionSection *section);
>         hwaddr (page_size)(MemoryRegionSection *section);
>         VFIOContainer *container;
> }
>
> Then there would be no reason for you to have separate wrappers for
> spapr.  VFIOType1 would have a single VFIOMemoryListener, you could have
> an array of two.

Sorry, I am missing the point here...

I cannot just have an array of these - I will have to store an address 
spaces per a listener in a container to implement filter() so I'd rather 
store just an address space and not add filter() at all. And I will still 
need "memory: Add reporting of supported page sizes" - or there is no way 
to implement it all. So I still end up having 6 callbacks in 
hw/vfio/common.c. What does this win for us?


> >   static void vfio_listener_release(VFIOContainer *container)
> > @@ -684,7 +741,7 @@ static int vfio_connect_container(VFIOGroup *group, 
> > AddressSpace *as)
> >               goto free_container_exit;
> >           }
> >
> > -        container->iommu_data.type1.listener = vfio_memory_listener;
> > +        container->iommu_data.type1.listener = vfio_type1_iommu_listener;
> >           container->iommu_data.release = vfio_listener_release;
> >
> >           memory_listener_register(&container->iommu_data.type1.listener,
> > @@ -724,7 +781,7 @@ static int vfio_connect_container(VFIOGroup *group, 
> > AddressSpace *as)
> >               goto free_container_exit;
> >           }
> >
> > -        container->iommu_data.type1.listener = vfio_memory_listener;
> > +        container->iommu_data.type1.listener = vfio_spapr_iommu_listener;
> >           container->iommu_data.release = vfio_listener_release;
> >
> >           memory_listener_register(&container->iommu_data.type1.listener,


--
Alexey