Re: [Qemu-devel] [PULL RESEND 12/19] vmxnet3: Convert ring values to uint32_t's

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Laurent Vivier (lvivier@redhat.com) wrote:
> On 06/03/2017 06:25, Jason Wang wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > The index's in the Vmxnet3Ring were migrated as 32bit ints
> > yet are declared as size_t's.  They appear to be derived
> > from 32bit values loaded from guest memory, so actually
> > store them as that.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Acked-by: Dmitry Fleytman <dmitry@daynix.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > ---
> >  hw/net/vmxnet3.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> > index e13a798..224c109 100644
> > --- a/hw/net/vmxnet3.c
> > +++ b/hw/net/vmxnet3.c
> > @@ -141,17 +141,17 @@ typedef struct VMXNET3Class {
> >  /* Cyclic ring abstraction */
> >  typedef struct {
> >      hwaddr pa;
> > -    size_t size;
> > -    size_t cell_size;
> > -    size_t next;
> > +    uint32_t size;
> > +    uint32_t cell_size;
> > +    uint32_t next;
> >      uint8_t gen;
> >  } Vmxnet3Ring;
> >  
> >  static inline void vmxnet3_ring_init(PCIDevice *d,
> >  				     Vmxnet3Ring *ring,
> >                                       hwaddr pa,
> > -                                     size_t size,
> > -                                     size_t cell_size,
> > +                                     uint32_t size,
> > +                                     uint32_t cell_size,
> >                                       bool zero_region)
> >  {
> >      ring->pa = pa;
> > @@ -166,7 +166,7 @@ static inline void vmxnet3_ring_init(PCIDevice *d,
> >  }
> >  
> >  #define VMXNET3_RING_DUMP(macro, ring_name, ridx, r)                         \
> > -    macro("%s#%d: base %" PRIx64 " size %zu cell_size %zu gen %d next %zu",  \
> > +    macro("%s#%d: base %" PRIx64 " size %u cell_size %u gen %d next %u",  \
> >            (ring_name), (ridx),                                               \
> >            (r)->pa, (r)->size, (r)->cell_size, (r)->gen, (r)->next)
> >  
> > 
> 
> 
> David, with '-dump-vmstate' with 2.8 machine type and with v2.8 and
> master I can see the size of "txq_descr" and "rxq_descr" changes because
> of "sizeof(Vmxnet3TxqDescr)" and "sizeof(Vmxnet3RxqDescr)". This changes
> because the size of Vmxnet3Ring has changed with the s/size_t/uint32_t/":
> 
>         {
>           "field": "txq_descr",
>           "version_id": 0,
>           "field_exists": false,
>           "size": 176
>         },
>         {
>           "field": "rxq_descr",
>           "version_id": 0,
>           "field_exists": false,
>           "size": 216
>         },
> 
> becomes:
> 
>         {
>           "field": "txq_descr",
>           "version_id": 0,
>           "field_exists": false,
>           "size": 144
>         },
>         {
>           "field": "rxq_descr",
>           "version_id": 0,
>           "field_exists": false,
>           "size": 168
>         },

But the old migration code used to write these fields using qemu_put_be32
(from a11f5cb005f9854f0d78da97fc23adf5bc8c83f3)

-static void vmxnet3_put_ring_to_file(QEMUFile *f, Vmxnet3Ring *r)
-{
-    qemu_put_be64(f, r->pa);
-    qemu_put_be32(f, r->size);
-    qemu_put_be32(f, r->cell_size);
-    qemu_put_be32(f, r->next);
-    qemu_put_byte(f, r->gen);
-}

+static const VMStateDescription vmstate_vmxnet3_ring = {
+    .name = "vmxnet3-ring",
+    .version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(pa, Vmxnet3Ring),
+        VMSTATE_UINT32(size, Vmxnet3Ring),
+        VMSTATE_UINT32(cell_size, Vmxnet3Ring),
+        VMSTATE_UINT32(next, Vmxnet3Ring),
+        VMSTATE_UINT8(gen, Vmxnet3Ring),
+        VMSTATE_END_OF_LIST()
+    }
 };

so they used to be size_t's written with be32 and now they're uint32_t's
written as 32bit - so that should be the same.
I'm not sure i understand where the old txq_descr sizes come from - what
managed to print the 176 number before it was converted to VMState?

> And if I try a migration, I have:
> 
> qemu/migration/vmstate.c:112: vmstate_load_state: Assertion `first_elem
> || !n_elems' failed.

Interesting; that's Halil's new assert; I need to look.

Dave

> Laurent
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK