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

[Jordan Justen]

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.

-Jordan

> diff --git a/kvm-all.c b/kvm-all.c
> index 8e7bbf8..405480e 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -206,7 +206,8 @@ static int kvm_set_user_memory_region(KVMState *s, 
> KVMSlot *slot)
>      if (s->migration_log) {
>          mem.flags |= KVM_MEM_LOG_DIRTY_PAGES;
>      }
> -    if (mem.flags & KVM_MEM_READONLY) {
> +
> +    if (slot->memory_size && mem.flags & KVM_MEM_READONLY) {
>          /* Set the slot size to 0 before setting the slot to the desired
>           * value. This is needed based on KVM commit 75d61fbc. */
>          mem.memory_size = 0;
>
>