* [Qemu-devel] [PATCH] exec: Fix qemu_ram_block_from_host for Xen
@ 2016-06-09 15:56 Anthony PERARD
2016-06-13 8:16 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Anthony PERARD @ 2016-06-09 15:56 UTC (permalink / raw)
To: qemu-devel
Cc: xen-devel, Stefano Stabellini, Paolo Bonzini, Peter Crosthwaite,
Richard Henderson, Anthony PERARD
Since f615f39 (exec: remove ram_addr argument from
qemu_ram_block_from_host), migration under Xen is likely to fail, with a
SEGV of QEMU. But the commit only reveal a bug with the calculation of
the offset value in qemu_ram_block_from_host().
This patch calculates the offset from the ram_addr as
qemu_ram_addr_from_host() will later calculate the ram_addr from the
offset.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
exec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index f2c9e37..f13106d 100644
--- a/exec.c
+++ b/exec.c
@@ -1935,7 +1935,7 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
ram_addr = xen_ram_addr_from_mapcache(ptr);
block = qemu_get_ram_block(ram_addr);
if (block) {
- *offset = (host - block->host);
+ *offset = ram_addr - block->offset;
}
rcu_read_unlock();
return block;
--
Anthony PERARD
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [Qemu-devel] [PATCH] exec: Fix qemu_ram_block_from_host for Xen
2016-06-09 15:56 [Qemu-devel] [PATCH] exec: Fix qemu_ram_block_from_host for Xen Anthony PERARD
@ 2016-06-13 8:16 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2016-06-13 8:16 UTC (permalink / raw)
To: Anthony PERARD, qemu-devel
Cc: xen-devel, Stefano Stabellini, Peter Crosthwaite,
Richard Henderson
On 09/06/2016 17:56, Anthony PERARD wrote:
> Since f615f39 (exec: remove ram_addr argument from
> qemu_ram_block_from_host), migration under Xen is likely to fail, with a
> SEGV of QEMU. But the commit only reveal a bug with the calculation of
> the offset value in qemu_ram_block_from_host().
>
> This patch calculates the offset from the ram_addr as
> qemu_ram_addr_from_host() will later calculate the ram_addr from the
> offset.
>
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
> exec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/exec.c b/exec.c
> index f2c9e37..f13106d 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1935,7 +1935,7 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
> ram_addr = xen_ram_addr_from_mapcache(ptr);
> block = qemu_get_ram_block(ram_addr);
> if (block) {
> - *offset = (host - block->host);
> + *offset = ram_addr - block->offset;
> }
> rcu_read_unlock();
> return block;
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Feel free to send a pull request yourself!
Thanks, and sorry for the breakage. Indeed the broken code comes from
commit 422148d3e56c3c9a07c0cf36c1e0a0b76f09c357.
Paolo
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