From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH for-4.6] xen/arm: vgic-v2: Map the GIC virtual CPU interface with the correct size Date: Fri, 18 Sep 2015 09:53:30 +0100 Message-ID: <1442566410.18856.252.camel@citrix.com> References: <1442512803-798-1-git-send-email-julien.grall@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZcrQF-0001pR-4L for xen-devel@lists.xenproject.org; Fri, 18 Sep 2015 08:53:35 +0000 In-Reply-To: <1442512803-798-1-git-send-email-julien.grall@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall , xen-devel@lists.xenproject.org Cc: Wei.Liu2@citrix.com, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On Thu, 2015-09-17 at 19:00 +0100, Julien Grall wrote: > On GICv2, the GIC virtual CPU interface is at minimum 8KB. Due some to > some necessary quirk for GIC using 64KB stride, we are mapping the > region in 2 time. > The first mapping is 4KB and the second one is 8KB, i.e 12KB in total. > Although the minimum supported size (and widely used) is 8KB. This means > that we are mapping 4KB more to any guest using GICv2. > > While this looks scary at first glance, the GIC virtual CPU interface is > most frequently at the end the GIC I/O region. So we will most likely > map an an unused I/O region or a mirrored version of GICV for platform > using 64KB stride. > > Nonetheless, fix the second mapping to only map 4KB. > > Signed-off-by: Julien Grall Acked-by: Ian Campbell > --- > > This is a candidate for Xen 4.6 and backport to Xen 4.5. I concur and with Wei not being around I shall plan to apply later today unless there are objections.