From mboxrd@z Thu Jan  1 00:00:00 1970
From: Razvan Cojocaru <rcojocaru@bitdefender.com>
Subject: Re: [PATCH 4/5] xen/vm_event: Deny MSR writes if
 refused by vm_event reply
Date: Mon, 11 May 2015 10:44:37 +0300
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To: Jan Beulich <JBeulich@suse.com>
Cc: kevin.tian@intel.com, wei.liu2@citrix.com, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, andrew.cooper3@citrix.com, tim@xen.org, xen-devel@lists.xen.org, eddie.dong@intel.com, Aravind.Gopalakrishnan@amd.com, jun.nakajima@intel.com, suravee.suthikulpanit@amd.com, boris.ostrovsky@oracle.com, keir@xen.org, ian.jackson@eu.citrix.com
List-Id: xen-devel@lists.xenproject.org

On 05/11/2015 10:03 AM, Jan Beulich wrote:
>>>> On 08.05.15 at 19:05, <rcojocaru@bitdefender.com> wrote:
>> On 05/08/2015 07:23 PM, Jan Beulich wrote:
>>>>>> On 06.05.15 at 19:12, <rcojocaru@bitdefender.com> wrote:
>>>> --- a/xen/include/asm-x86/domain.h
>>>> +++ b/xen/include/asm-x86/domain.h
>>>> @@ -518,6 +518,11 @@ struct arch_vcpu
>>>>          struct vm_event_emul_read_data emul_read_data;
>>>>      } vm_event;
>>>>  
>>>> +    struct {
>>>> +        bool_t do_write;
>>>> +        uint64_t msr;
>>>> +        uint64_t value;
>>>> +    } msr_write;
>>>>  };
>>>
>>> Again a growth of struct vcpu by 24 bytes for everyone even though
>>> quite likely only very few VMs would actually need this. To be honest
>>> I'd even be hesitant to accept a pointer addition here. Perhaps this
>>> should be a suitably sized, dynamically allocated array hanging off of
>>> struct domain?
>>
>> Sorry, I don't follow the dynamically allocated _array_ part. Could you
>> please give a small example of what you mean?
> 
> Have a pointer in struct arch_domain which gets populated only
> when needed, and if so by an array allocation with the array
> dimension being the maximum number of vCPU-s the domain may
> have. That way the memory overhead for non-monitored domains
> is a pointer per domain (as opposed to quite a bit more unused
> space per vCPU).

All clear now.


Thanks,
Razvan