Re: [Qemu-devel] [BUG]: kvm_set_phys_mem: error unregistering overlapping slot: Invalid argument

[Jordan Justen]

On Fri, May 31, 2013 at 12:14 AM, Jordan Justen <address@hidden> wrote:
> On Thu, May 30, 2013 at 11:51 PM, Xiao Guangrong
> <address@hidden> wrote:
>> On 05/31/2013 12:50 AM, Jordan Justen wrote:
>>> On Thu, May 30, 2013 at 9:08 AM, Luiz Capitulino <address@hidden> wrote:
>>>> On Thu, 30 May 2013 18:03:04 +0200
>>>> Paolo Bonzini <address@hidden> wrote:
>>>>
>>>>> Il 30/05/2013 17:46, Luiz Capitulino ha scritto:
>>>>>> The culprit is commit:
>>>>>>
>>>>>> commit 235e8982ad393e5611cb892df54881c872eea9e1
>>>>>> Author: Jordan Justen <address@hidden>
>>>>>> Date:   Wed May 29 01:27:26 2013 -0700
>>>>>>
>>>>>>     kvm: support using KVM_MEM_READONLY flag for regions
>>>>>>
>>>>>> I'm running 3.9.2-200.fc18, btw. And, error checking is missing on the
>>>>>> first call to kvm_vm_ioctl().
>>>
>>> As noted in the code, the first call is for KVM commit 75d61fbc.
>>>
>>> I'm not sure we want to fail if an error occurs when making that call.
>>> (I'm pretty sure we don't want to in fact.)
>>>
>>> Xiao, any thoughts?
>>
>> I have reproduced this bug, it seems that the bug is caused by double free
>> the memslot. After these change, it can boot the guest now.
>
> I think that I might have found that the flash memory had an issue
> with transitioning from flash to rom mode with code like this on the
> 3.8 kernel. I'll test it on 3.8 & 3.9.

Yes, the issue still occurs on 3.9, and even the "double free" doesn't
work on 3.9 like it did on 3.8.

This issue is a bit of a corner case for flash, but still important. I
hope maybe Xiao might have time to help me understand it. (I'll email
Xiao off-list about this.)

But, for now, I think Xiao's patch will fix things for the non-flash
case, and will not totally break flash support either.

-Jordan