| Message ID | 20170321223151.12984-1-Andrew.Baumann@microsoft.com |
|---|---|
| State | New |
| Headers | show |
On 03/21/2017 05:31 PM, Andrew Baumann wrote: > "long" is 32-bits on win32, but we need to promote it to a 64-bit hwaddr > before negating, or else the top half of the address is truncated > > Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com> > --- > include/hw/virtio/virtio.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 15efcf2..a0a8543 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -34,7 +34,7 @@ struct VirtQueue; > static inline hwaddr vring_align(hwaddr addr, > unsigned long align) > { > - return (addr + align - 1) & ~(align - 1); > + return (addr + align - 1) & ~(hwaddr)(align - 1); Why not just use the QEMU_ALIGN_DOWN macro, instead of open-coding it? (Hmm - a good BiteSized task might be to come up with a Coccinelle script to help replace all open-coded rounding functions with appropriate macro calls instead)
> From: Eric Blake [mailto:eblake@redhat.com] > Sent: Tuesday, 21 March 2017 15:52 > > On 03/21/2017 05:31 PM, Andrew Baumann wrote: > > "long" is 32-bits on win32, but we need to promote it to a 64-bit hwaddr > > before negating, or else the top half of the address is truncated > > > > Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com> > > --- > > include/hw/virtio/virtio.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > index 15efcf2..a0a8543 100644 > > --- a/include/hw/virtio/virtio.h > > +++ b/include/hw/virtio/virtio.h > > @@ -34,7 +34,7 @@ struct VirtQueue; > > static inline hwaddr vring_align(hwaddr addr, > > unsigned long align) > > { > > - return (addr + align - 1) & ~(align - 1); > > + return (addr + align - 1) & ~(hwaddr)(align - 1); > > Why not just use the QEMU_ALIGN_DOWN macro, instead of open-coding it? Well, this code is aligning up, but yes the ALIGN_UP macro looks like it should also avoid the type promotion problem. This patch is just the minimally-invasive change after discovering the bug. Let me know if you want me to spin another patch with the macro. Andrew
Am 22.03.2017 um 00:06 schrieb Andrew Baumann: >> From: Eric Blake [mailto:eblake@redhat.com] >> Sent: Tuesday, 21 March 2017 15:52 >> >> On 03/21/2017 05:31 PM, Andrew Baumann wrote: >>> "long" is 32-bits on win32, but we need to promote it to a 64-bit hwaddr >>> before negating, or else the top half of the address is truncated >>> >>> Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com> >>> --- >>> include/hw/virtio/virtio.h | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h >>> index 15efcf2..a0a8543 100644 >>> --- a/include/hw/virtio/virtio.h >>> +++ b/include/hw/virtio/virtio.h >>> @@ -34,7 +34,7 @@ struct VirtQueue; >>> static inline hwaddr vring_align(hwaddr addr, >>> unsigned long align) >>> { >>> - return (addr + align - 1) & ~(align - 1); >>> + return (addr + align - 1) & ~(hwaddr)(align - 1); >> >> Why not just use the QEMU_ALIGN_DOWN macro, instead of open-coding it? > > Well, this code is aligning up, but yes the ALIGN_UP macro looks like it should also avoid the type promotion problem. This patch is just the minimally-invasive change after discovering the bug. > > Let me know if you want me to spin another patch with the macro. > > Andrew Yes, please use QEMU_ALIGN_UP in an updated patch. This is a bug fix needed for v2.9.0. Fixing all other code locations which round up or down with Coccinelle is a separate task, nothing which is needed for the next QEMU version. Thanks, Stefan
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 15efcf2..a0a8543 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -34,7 +34,7 @@ struct VirtQueue; static inline hwaddr vring_align(hwaddr addr, unsigned long align) { - return (addr + align - 1) & ~(align - 1); + return (addr + align - 1) & ~(hwaddr)(align - 1); } typedef struct VirtQueue VirtQueue;
"long" is 32-bits on win32, but we need to promote it to a 64-bit hwaddr before negating, or else the top half of the address is truncated Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com> --- include/hw/virtio/virtio.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)