Re: [Xen-devel] [PATCH] qemu-xen-traditionnal, Fix dirty logging during migration.

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On 23/07/12 11:42, Stefano Stabellini wrote:
> On Fri, 20 Jul 2012, Anthony PERARD wrote:
> > This moves the xen_modified_memory call from cpu_physical_memory_map to
> > cpu_physical_memory_unmap because the memory could be migrated before the
> > device model have written to it.
> >
> > The xen_ram_addr_from_mapcache function is imported from QEMU.
> >
> > Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> >
> > ---
> >   hw/xen_machine_fv.c |   39 +++++++++++++++++++++++++++++++++++++++
> >   i386-dm/exec-dm.c   |   10 ++++++----
> >   qemu-xen.h          |    1 +
> >   3 files changed, 46 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/xen_machine_fv.c b/hw/xen_machine_fv.c
> > index fdad42a..c358944 100644
> > --- a/hw/xen_machine_fv.c
> > +++ b/hw/xen_machine_fv.c
> > @@ -223,6 +223,45 @@ void qemu_invalidate_entry(uint8_t *buffer)
> >       qemu_free(entry);
> >   }
> >
> > +target_phys_addr_t xen_ram_addr_from_mapcache(void *ptr)
> > +{
> > +    struct map_cache *entry = NULL;
> > +    struct map_cache_rev *reventry;
> > +    target_phys_addr_t paddr_index;
> > +    int found = 0;
> > +
> > +    TAILQ_FOREACH(reventry, &locked_entries, next) {
> > +        if (reventry->vaddr_req == ptr) {
> > +            paddr_index = reventry->paddr_index;
> > +            found = 1;
> > +            break;
> > +        }
> > +    }
> > +    if (!found) {
> > +        fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
> > +        TAILQ_FOREACH(reventry, &locked_entries, next) {
> > +            fprintf(stderr, "   %#10lx -> %p is present\n",
> > +                    reventry->paddr_index,
> > +                    reventry->vaddr_req);
> > +        }
> > +        abort();
> > +        return 0;
> > +    }
> > +
> > +    entry = &mapcache_entry[paddr_index % nr_buckets];
> > +    while (entry && (entry->paddr_index != paddr_index)) {
> > +        entry = entry->next;
> > +    }
> > +    if (!entry) {
> > +        fprintf(stderr,
> > +                "Trying to find address %p that is not in the mapcache!\n",
> > +                ptr);
> > +        return 0;
> > +    }
> > +    return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
> > +        ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
> > +}
> > +
> >   void qemu_invalidate_map_cache(void)
> >   {
> >       unsigned long i;
> > diff --git a/i386-dm/exec-dm.c b/i386-dm/exec-dm.c
> > index 96274d9..bf27a6a 100644
> > --- a/i386-dm/exec-dm.c
> > +++ b/i386-dm/exec-dm.c
> > @@ -820,10 +820,6 @@ void *cpu_physical_memory_map(target_phys_addr_t addr,
> >       if ((*plen) > l)
> >           *plen = l;
> >   #endif
> > -    if (xen_logdirty_enable)
> > -        xc_hvm_modified_memory(xc_handle, domid, addr >> TARGET_PAGE_BITS,
> > -                ((addr + l + TARGET_PAGE_SIZE - 1) >> TARGET_PAGE_BITS)
> > -                    - (addr >> TARGET_PAGE_BITS));
> >
> >       return qemu_map_cache(addr, 1);
> >   }
> > @@ -835,6 +831,12 @@ void *cpu_physical_memory_map(target_phys_addr_t addr,
> >   void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
> >                                  int is_write, target_phys_addr_t access_len)
> >   {
> > +    if (xen_logdirty_enable && is_write) {
> > +        target_phys_addr_t addr = xen_ram_addr_from_mapcache(buffer);
> > +        xc_hvm_modified_memory(xc_handle, domid, addr >> TARGET_PAGE_BITS,
> > +            ((addr + access_len + TARGET_PAGE_SIZE - 1) >> TARGET_PAGE_BITS)
> > +                - (addr >> TARGET_PAGE_BITS));
> > +    }
> >       qemu_invalidate_entry(buffer);
> >       cpu_notify_map_clients();
> >   }
> Considering that on qemu-xen-traditional there is just one caller of
> qemu_invalidate_entry, that is cpu_physical_memory_unmap, we can just
> add the xc_hvm_modified_memory call there and avoid introducing
> xen_ram_addr_from_mapcache.
OK, that would simplifies things.

--
Anthony PERARD

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