Re: [Qemu-devel] kvm bug in __rmap_clear_dirty during live migration

From: Huang, Kai
Date: Mon Feb 27 2017 - 02:42:33 EST




On 2/25/2017 2:44 PM, Herongguang (Stephen) wrote:


On 2017/2/24 23:14, Paolo Bonzini wrote:


On 24/02/2017 16:10, Chris Friesen wrote:
On 02/23/2017 08:23 PM, Herongguang (Stephen) wrote:

On 2017/2/22 22:43, Paolo Bonzini wrote:

Hopefully Gaohuai and Rongguang can help with this too.

Paolo

Yes, we are looking into and testing this.

I think this can result in any memory corruption, if VM1 writes its
PML buffer into VM2âs VMCS (since sched_in/sched_out notifier of VM1
is not registered yet), then VM1 is destroyed (hence its PML buffer
is freed back to kernel), after that, VM2 starts migration, so CPU
logs VM2âs dirty GFNS into a freed memory, results in any memory
corruption.

As its severity, this commit
(http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4e59516a12a6ef6dcb660cb3a3f70c64bd60cfec)


is eligible to back port to kernel stable.

Are we expecting that fix to resolve the original issue, or is it a
separate issue that needs fixing in stable?

It should be the original issue.

Paolo

.

Yes, I agree, though we are still testing.


Hi Stephen,

Sorry for late reply. I was taking the whole week off last week. How's the test going?

Thanks,
-Kai