Re: [Qemu-devel] [PATCH 3/4] exec: extract address_space_translate_iommu, fix page_mask corner case

[Paolo Bonzini]

----- Original Message -----
> From: "Peter Xu" <address@hidden>
> To: "Paolo Bonzini" <address@hidden>
> Cc: address@hidden
> Sent: Friday, May 4, 2018 6:22:31 AM
> Subject: Re: [Qemu-devel] [PATCH 3/4] exec: extract 
> address_space_translate_iommu, fix page_mask corner case
> 
> On Tue, Apr 17, 2018 at 04:08:01PM +0200, Paolo Bonzini wrote:
> 
> [...]
> 
> > +static MemoryRegionSection address_space_translate_iommu(IOMMUMemoryRegion
> > *iommu_mr,
> > +                                                         hwaddr *xlat,
> > +                                                         hwaddr *plen_out,
> > +                                                         hwaddr
> > *page_mask_out,
> > +                                                         bool is_write,
> > +                                                         bool is_mmio,
> > +                                                         AddressSpace
> > **target_as)
> > +{
> > +    MemoryRegionSection *section;
> > +    hwaddr page_mask = (hwaddr)-1;
> > +
> > +    do {
> > +        hwaddr addr = *xlat;
> > +        IOMMUMemoryRegionClass *imrc =
> > memory_region_get_iommu_class_nocheck(iommu_mr);
> > +        IOMMUTLBEntry iotlb = imrc->translate(iommu_mr, addr, is_write ?
> > +                                              IOMMU_WO : IOMMU_RO);
> > +
> > +        if (!(iotlb.perm & (1 << is_write))) {
> > +            goto unassigned;
> > +        }
> > +
> > +        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
> > +                | (addr & iotlb.addr_mask));
> > +        page_mask &= iotlb.addr_mask;
> > +        *plen_out = MIN(*plen_out, (addr | iotlb.addr_mask) - addr + 1);
> > +        *target_as = iotlb.target_as;
> > +
> > +        section = address_space_translate_internal(
> > +                address_space_to_dispatch(iotlb.target_as), addr, xlat,
> > +                plen_out, is_mmio);
> > +        if (!section) {
> > +            goto unassigned;
> 
> (we won't reach here, will we?)

Good point, I'll fix that.

Paolo

> 
> Reviewed-by: Peter Xu <address@hidden>
> 
> --
> Peter Xu
>