On 02.07.2012 17:05, Avi Kivity wrote:
On 06/28/2012 12:38 PM, Peter Lieven wrote:
does anyone know whats that here in handle_mmio?
/* hack: Red Hat 7.1 generates these weird accesses. */
if ((addr> 0xa0000-4&& addr<= 0xa0000)&& kvm_run->mmio.len == 3)
return 0;
Just what it says. There is a 4-byte access to address 0x9ffff. The
first byte lies in RAM, the next three bytes are in mmio. qemu is
geared to power-of-two accesses even though x86 can generate accesses to
any number of bytes between 1 and 8.
I just stumbled across the word "hack" in the comment. When the race
occurs the CPU is basically reading from 0xa0000 in an endless loop.
It appears that this has happened with your guest. It's not impossible
that it's genuine.
I had a lot to do the last days, but I update our build environment to
Ubuntu LTS 12.04 64-bit Server which is based on Linux 3.2.0. I still
see the issue. If I use the kvm Module provided with the kernel it is
working correctly. If I use kvm-kmod-3.4 with qemu-kvm-1.0.1 (both
from sourceforge) I can reproduce the race condition.
I will keep you posted when I have more evidence.
Thanks,
Peter
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