Re: [PATCH 01/11] Add shared memory hypercall to PV Linux guest.

From: Avi Kivity <avi@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/11] Add shared memory hypercall to PV Linux guest.
Date: Tue, 03 Nov 2009 07:15:10 +0200	[thread overview]
Message-ID: <4AEFBC5E.7020300@redhat.com> (raw)
In-Reply-To: <20091102161809.GG27911@redhat.com>

On 11/02/2009 06:18 PM, Gleb Natapov wrote:
>>> +#define KVM_PV_SHM_VERSION 1
>>>        
>> versions = bad, feature bits = good
>>
>>      
> I have both! Do you want me to drop version?
>    

Yes.  Once a kernel is released you can't realistically change the version.

>> Some documentation for this?
>>
>> Also, the name should reflect the pv pagefault use.  For other uses
>> we can register other areas.
>>
>>      
> I wanted it to be generic, but I am fine with making it apf specific.
> It will allow to make it smaller too.
>    

Maybe we can squeeze it into the page-fault error code?

>> would solve this.  I prefer using put_user() though than a permanent
>> get_user_pages().
>>
>>      
> I want to prevent it from been swapped out.
>    

Since you don't prevent the page fault handler or code from being 
swapped out, you don't get anything out of it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.