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.
--
Thanks,
Igor
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