Re: [Qemu-devel] [PATCH for-1.7 0/5] fix address space size issues

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Nov 07, 2013 at 12:22:29AM +0200, Marcel Apfelbaum wrote:
> On Thu, 2013-11-07 at 00:20 +0200, Michael S. Tsirkin wrote:
> > On Thu, Nov 07, 2013 at 12:09:50AM +0200, Marcel Apfelbaum wrote:
> > > On Wed, 2013-11-06 at 22:13 +0200, Michael S. Tsirkin wrote:
> > > > On Wed, Nov 06, 2013 at 09:54:03PM +0200, Marcel Apfelbaum wrote:
> > > > > On Wed, 2013-11-06 at 20:47 +0200, Michael S. Tsirkin wrote:
> > > > > > A bug reported by Luiz Capitulino let us to find
> > > > > > several bugs in memory address space setup.
> > > > > > 
> > > > > > One issue is that gdb stub can give us arbitrary addresses
> > > > > > and we'll try to access them.
> > > > > > Since our lookup ignored high bits in the address,
> > > > > > we hit a wrong section and got a crash.
> > > > > > In fact, PCI devices can access arbitrary addresses too,
> > > > > > so we should just make lookup robust against this case.
> > > > > > 
> > > > > > Another issue has to do with size of regions.
> > > > > > memory API uses UINT64_MAX so say "all 64 bit" but
> > > > > > some devices mistakenly used INT64_MAX.
> > > > > > 
> > > > > > It should not affect most systems in practice as
> > > > > > everything should be limited by address space size,
> > > > > > but it's an API misuse that we should not keep around,
> > > > > > and it will become a problem if a system with 64 bit
> > > > > > target address hits this path.
> > > > > > 
> > > > > > Patch 1 fixes an actual bug.
> > > > > > The rest of patches make code cleaner and more robust.
> > > > > > 
> > > > > > Michael S. Tsirkin (4):
> > > > > >   exec: don't ignore high address bits on lookup
> > > > > >   pci: fix address space size for bridge
> > > > > >   exec: don't ignore high address bits on set
> > > > > >   spapr_pci: s/INT64_MAX/UINT64_MAX/
> > > > > > 
> > > > > > Paolo Bonzini (1):
> > > > > >   pc: s/INT64_MAX/UINT64_MAX/
> > > > > > 
> > > > > >  exec.c              | 9 +++++++++
> > > > > >  hw/i386/pc_piix.c   | 2 +-
> > > > > >  hw/i386/pc_q35.c    | 2 +-
> > > > > >  hw/pci/pci_bridge.c | 2 +-
> > > > > >  hw/ppc/spapr_pci.c  | 2 +-
> > > > > >  5 files changed, 13 insertions(+), 4 deletions(-)
> > > > > > 
> > > > > 
> > > > > Reviewed-by: Marcel Apfelbaum <marcel.a@redhat.com>
> > > > > 
> > > > 
> > > > Please don't apply this.
> > > > 
> > > > I didn't post the patches - I only sent them to Marcel :)
> > > > And the reason is that the assert in exec. detects more bugs with
> > > > over-writing page-tables: just run make check.
> > > > 
> > > > I think we need to get a handle on them first before applying.
> > > > 
> > > 
> > > Found the issues with make check, so that this series can be posted.
> > > I'll send a proper patch tomorrow:
> > 
> > Cool. So pls make this patch 1 and the rest can go on top.
> > Also maybe add TARGET_PHYS_ADDR_SPACE_MAX to avoid
> >  TARGET_PHYS_ADDR_SPACE_BITS == 64 ?
> >                             UINT64_MAX : (0x1ULL << TARGET_PHYS_ADDR_SPACE_BITS)
> > everywhere.
> > 
> Good idea, I'll use this.
> 
> > though that is not a must.
> > 
> > Does hw/ppc/spapr_vio.c need a patch too?
> > Could not figure out where does the "as" come from there ...
> > probably not an issue.
> Wasn't needed for make check. That doesn't mean is not an issue.
> 
> > We also need some more tests done.
> That's for sure, in the mean time I'll put the assert inside
> an ifdef as you suggested.
> 
> Thanks,
> Marcel


maybe 

if (index > XXX) {
#ifdef DEBUG
	fprintf(stderr, "scary warnings");
#endif
	return
}

so we don't corrupt pagetable ..

> > 
> > > 
> > > diff --git a/hw/alpha/typhoon.c b/hw/alpha/typhoon.c
> > > index 59e1bb8..c203935 100644
> > > --- a/hw/alpha/typhoon.c
> > > +++ b/hw/alpha/typhoon.c
> > > @@ -888,7 +888,8 @@ PCIBus *typhoon_init(ram_addr_t ram_size, ISABus **isa_bus,
> > >  
> > >      /* Host memory as seen from the PCI side, via the IOMMU.  */
> > >      memory_region_init_iommu(&s->pchip.iommu, OBJECT(s), &typhoon_iommu_ops,
> > > -                             "iommu-typhoon", UINT64_MAX);
> > > +                             "iommu-typhoon", TARGET_PHYS_ADDR_SPACE_BITS == 64 ?
> > > +                             UINT64_MAX : (0x1ULL << TARGET_PHYS_ADDR_SPACE_BITS));
> > >      address_space_init(&s->pchip.iommu_as, &s->pchip.iommu, "pchip0-pci");
> > >      pci_setup_iommu(b, typhoon_pci_dma_iommu, s);
> > >  
> > > diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> > > index ef45f4f..84b1309 100644
> > > --- a/hw/ppc/spapr_iommu.c
> > > +++ b/hw/ppc/spapr_iommu.c
> > > @@ -136,7 +136,9 @@ static int spapr_tce_table_realize(DeviceState *dev)
> > >      trace_spapr_iommu_new_table(tcet->liobn, tcet, tcet->table, tcet->fd);
> > >  
> > >      memory_region_init_iommu(&tcet->iommu, OBJECT(dev), &spapr_iommu_ops,
> > > -                             "iommu-spapr", UINT64_MAX);
> > > +                             "iommu-spapr",
> > > +                             TARGET_PHYS_ADDR_SPACE_BITS == 64 ?
> > > +                             UINT64_MAX : (0x1ULL << TARGET_PHYS_ADDR_SPACE_BITS));
> > >  
> > >      QLIST_INSERT_HEAD(&spapr_tce_tables, tcet, list);
> > > 
> > > 
> > > Thanks,
> > > Marcel
> > > 
> > > 
> 
>