Patchwork Memory-API: Make eventfd adhere to device endianness

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Submitter Alexander Graf
Date Oct. 15, 2012, 6:30 p.m.
Message ID <1350325828-11577-1-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/191624/
State New
Headers show

Comments

Alexander Graf - Oct. 15, 2012, 6:30 p.m.
Our memory API MMIO regions know the concept of device endianness. This
is used to automatically swap endianness between devices and host CPU,
depending on whether buses in between would swizzle the bits.

The ioeventfd value comparison does not adhere to that semantic though.
Probably because nobody has been running ioeventfd on a BE platform and
the only device implementing ioeventfd right now is LE (PCI) based.

So add swizzling to ioeventfd registration / deletion to make the rest
of the code as consistent as possible.

Thanks a lot to Michael Tsirkin to point me towards the right direction.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 memory.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
Avi Kivity - Oct. 17, 2012, 2:47 p.m.
On 10/15/2012 08:30 PM, Alexander Graf wrote:
> Our memory API MMIO regions know the concept of device endianness. This
> is used to automatically swap endianness between devices and host CPU,
> depending on whether buses in between would swizzle the bits.
> 
> The ioeventfd value comparison does not adhere to that semantic though.
> Probably because nobody has been running ioeventfd on a BE platform and
> the only device implementing ioeventfd right now is LE (PCI) based.
> 
> So add swizzling to ioeventfd registration / deletion to make the rest
> of the code as consistent as possible.
> 
> Thanks a lot to Michael Tsirkin to point me towards the right direction.

Thanks, applied.

Patch

diff --git a/memory.c b/memory.c
index 4f3ade0..d2f2fd6 100644
--- a/memory.c
+++ b/memory.c
@@ -1217,6 +1217,7 @@  void memory_region_add_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
+    adjust_endianness(mr, &mrfd.data, size);
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
@@ -1248,6 +1249,7 @@  void memory_region_del_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
+    adjust_endianness(mr, &mrfd.data, size);
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {