From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: AMD NPT support for Xen memory events Date: Wed, 16 Jul 2014 10:07:42 +0100 Message-ID: <53C640DE.6020507@citrix.com> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4231003771613100091==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Abhiroop Dabral , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org --===============4231003771613100091== Content-Type: multipart/alternative; boundary="------------040608090403090806020704" --------------040608090403090806020704 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit On 16/07/14 05:38, Abhiroop Dabral wrote: > Hi, > > I was looking at the code for the memory events for guest domain in > "xen/arch/xen/mm/mem_event.c". In the function "mem_event_domctl()" > for the case "XEN_DOMCTL_MEM_EVENT_OP_ACCESS", there is a comment that > "Currently only EPT is supported" and then a check is made for the vmx > presence and control returns if it is not Intel VT with an error. > I am trying to make the memory events working on AMD SVM with NPT > support. > My question is that is there a specific reason why AMD NPT is > supported there? > The things I should keep in mind/work on to support the memory events > on AMD NPT. > (Working on Xen 4.4 on HVM guests (windows XP 32 bit -PAE) I am not aware of any technical reasons why AMD support could not be added. I don't know why there is still a VMX check. c/s d928515d76 took out an EPT check and that appears to have been fine. Try it and see - it could be as easy as just deleting the vmx check. It would certainly be nice to try and get some parity back in our feature sets; a number of new features arrive as Intel-only because they were developed on Intel systems, rather than a specific reason why the feature wouldn't work on AMD. ~Andrew --------------040608090403090806020704 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit
On 16/07/14 05:38, Abhiroop Dabral wrote:
Hi,

I was looking at the code for the memory events for guest domain in "xen/arch/xen/mm/mem_event.c". In the function "mem_event_domctl()" for the case "XEN_DOMCTL_MEM_EVENT_OP_ACCESS", there is a comment that "Currently only EPT is supported" and then a check is made for the vmx presence and control returns if it is not Intel VT with an error. 
I am trying to make the memory events working on AMD SVM with NPT support. 
My question is that is there a specific reason why AMD NPT is supported there?
The things I should keep in mind/work on to support the memory events on AMD NPT.
(Working on Xen 4.4 on HVM guests (windows XP 32 bit -PAE)

I am not aware of any technical reasons why AMD support could not be added.

I don't know why there is still a VMX check.  c/s d928515d76 took out an EPT check and that appears to have been fine.

Try it and see - it could be as easy as just deleting the vmx check.

It would certainly be nice to try and get some parity back in our feature sets; a number of new features arrive as Intel-only because they were developed on Intel systems, rather than a specific reason why the feature wouldn't work on AMD.

~Andrew
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