From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: page->tlbflush_timestamp Date: Fri, 11 Oct 2013 15:17:29 +0100 Message-ID: <52580879.9090106@citrix.com> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2212176747560624219==" 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: =?UTF-8?B?5p2O5b635paw?= Cc: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org --===============2212176747560624219== Content-Type: multipart/alternative; boundary="------------020707090204010203050503" --------------020707090204010203050503 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit On 11/10/13 15:11, 李德新 wrote: > Hi, > page->tlbflush_timestamp is used to filter and flush the TLB > whenever type change of page happens. But why does xen flush TLB upon > the type change? And we already know that guest kernel will flush the > TLB in order to make the page table modifications take effect. > > Thanks! > > Best regards, > Sam The comment beside the code you reference explains why this is required for safety. On a more pragmatic view however, there is no Xen can trust that guest kernels are operating correctly. ~Andrew --------------020707090204010203050503 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: 8bit
On 11/10/13 15:11, 李德新 wrote:
Hi,
      page->tlbflush_timestamp is used to filter and flush the TLB whenever type change of page happens. But why does xen flush TLB upon the type change? And we already know that guest kernel will flush the TLB in order to make the page table modifications take effect.
     
      Thanks!

Best regards,
Sam

The comment beside the code you reference explains why this is required for safety.

On a more pragmatic view however, there is no Xen can trust that guest kernels are operating correctly.

~Andrew
--------------020707090204010203050503-- --===============2212176747560624219== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============2212176747560624219==--