Re: [PATCH 4/7] vm-event/x86: use vm_event_vcpu_enter properly

From: Corneliu ZUZU <czuzu@bitdefender.com>
To: Tamas K Lengyel <tamas@tklengyel.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
	Jan Beulich <jbeulich@suse.com>,
	Razvan Cojocaru <rcojocaru@bitdefender.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [PATCH 4/7] vm-event/x86: use vm_event_vcpu_enter properly
Date: Fri, 17 Jun 2016 12:24:38 +0300	[thread overview]
Message-ID: <4e5a3117-3321-e2ea-89fe-d42632c68aa1@bitdefender.com> (raw)
In-Reply-To: <CABfawhn7b5+g4WyeD+Dr=UnP0mj2fTiRoCYzAO03bxf3imho+A@mail.gmail.com>

On 6/16/2016 7:27 PM, Tamas K Lengyel wrote:
>> diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
>> index 1fec412..1e5445f 100644
>> --- a/xen/arch/x86/monitor.c
>> +++ b/xen/arch/x86/monitor.c
>> @@ -20,7 +20,6 @@
>>    */
>>
>>   #include <asm/monitor.h>
>> -#include <public/vm_event.h>
>>
>>   int arch_monitor_domctl_event(struct domain *d,
>>                                 struct xen_domctl_monitor_op *mop)
>> @@ -62,14 +61,6 @@ int arch_monitor_domctl_event(struct domain *d,
>>           else
>>               ad->monitor.write_ctrlreg_enabled &= ~ctrlreg_bitmask;
>>
>> -        if ( VM_EVENT_X86_CR3 == mop->u.mov_to_cr.index )
>> -        {
>> -            struct vcpu *v;
>> -            /* Latches new CR3 mask through CR0 code. */
>> -            for_each_vcpu ( d, v )
>> -                hvm_update_guest_cr(v, 0);
>> -        }
>> -
> So this block is not really getting relocated as the commit message
> suggests as much as being completely reworked at a different location?
> It would be better for it to be it's own separate patch as the changes
> are not trivial.

That's actually not reworked, it's completely removed since there's no 
need for it anymore.
That is: "latching of CR3 mask" is not done "through CR0" anymore but 
rather through the vm_event_vcpu_enter function instead and you don't 
have to do anything more here in arch_monitor_domctl_event for that to 
happen.

>>           domain_unpause(d);
>>
>>           break;
> Thanks,
> Tamas
>

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