qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [RFC PATCH qemu v3 2/4] vfio: Use different page size f


From: Alex Williamson
Subject: Re: [Qemu-devel] [RFC PATCH qemu v3 2/4] vfio: Use different page size for different IOMMU types
Date: Wed, 15 Jul 2015 20:51:49 -0600

On Thu, 2015-07-16 at 11:26 +1000, Alexey Kardashevskiy wrote:
> 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 

You're not storing an address space now.

> need "memory: Add reporting of supported page sizes" - or there is no way 

Just like you do now.

> to implement it all. So I still end up having 6 callbacks in 
> hw/vfio/common.c. What does this win for us?

Nothing you're suggesting adds any more callbacks.

The current filter is vfio_listener_skipped_section().  The iommu filter
is simply:

bool vfio_iommu_listener_skipped_section(mr)
{
  return vfio_listener_skipped_section(mr) || !memory_region_is_iommu(mr);
}

Notice how I didn't have to call it spapr because it's probably what any
guest iommu is going to do...

The v2 spapr filter is:

bool vfio_nodump_listener_skipped_section(mr)
{
  return vfio_listener_skipped_section(mr) || memory_region_is_skip_dump(mr);
}

Notice again that we can use generic functions and not make everything
spapr specific.

The page_size callbacks are similarly trivial, the iommu one obviously
calls memory_region_iommu_get_page_sizes, the other one uses
~qemu_real_host_page_mask.  Again, nothing spapr specific.

The container of course points back to the container and now
vfio_listener_region_add() simply does:

VFIOMemoryListener vlistener = container_of(listener, VFIOMemoryListener, 
listener);
VFIOContainer = vlistener->container;
hwaddr page_mask = vlistener->page_size(mr);

if (vlistener->filter && vlistener->filter(mr)) {
    return
}
...

And suddenly we get to piece together a handful of _generic_ helper
functions into a VFIOMemoryListener and we're not adding a new pair of
wrappers for everything and duplicating trivial setup.  Thanks,

Alex

> >>
> >>   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,
> >
> >
> >
> 
> 






reply via email to

[Prev in Thread] Current Thread [Next in Thread]