On 09/02/2011 04:47 PM, Konrad Rzeszutek Wilk wrote:
On Fri, Sep 02, 2011 at 04:01:35PM +0200, Igor Mammedov wrote:
On 09/02/2011 03:40 PM, Konrad Rzeszutek Wilk wrote:
On Fri, Sep 02, 2011 at 10:18:23AM +0200, Igor Mammedov wrote:
On 09/01/2011 06:46 PM, Jeremy Fitzhardinge wrote:
On 09/01/2011 04:46 AM, Igor Mammedov wrote:
If vmalloc page_fault happens inside of interrupt handler with interrupts
disabled then on exit path from exception handler when there is no pending
interrupts, the following code (arch/x86/xen/xen-asm_32.S:112):
cmpw $0x0001, XEN_vcpu_info_pending(%eax)
sete XEN_vcpu_info_mask(%eax)
will enable interrupts even if they has been previously disabled according to
eflags from the bounce frame (arch/x86/xen/xen-asm_32.S:99)
testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp)
setz XEN_vcpu_info_mask(%eax)
Solution is in setting XEN_vcpu_info_mask only when it should be set
according to
cmpw $0x0001, XEN_vcpu_info_pending(%eax)
but not clearing it if there isn't any pending events.
Reproducer for bug is attached to RHBZ 707552
Signed-off-by: Igor Mammedov<imammedo@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge<jeremy@xxxxxxxx>
One nit, this should be acked-by or reviewed-by, not signed-off-by,
since the patch isn't passing through my hands.
J
I'm new to this stuff, would you like me to re-post it?
That is OK. I fixed it up in the git commit. Thanks for finding this one!
You're welcome!
I've learned a lot while debugging it. In particular, how to use kvm and qemu's
gdbstub to debug xen and guest using gdb.
Oh, would you be interested in writting a blog article on xen.org by any chance?
That sounds pretty nifty!
Sure, that is on my todo list. I'll just gather separated bits of information
together, on how to prepare host for debugging. And description of problems and
limitations of this approach, that I've stumbled on.
--
Thanks,
Igor
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home