From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v8 2/8] xen/arm: Add functions of mapping between vCPUID and virtual affinity Date: Wed, 17 Jun 2015 13:48:51 +0100 Message-ID: <1434545331.13744.362.camel@citrix.com> References: <1434097969-16793-1-git-send-email-cbz@baozis.org> <1434097969-16793-3-git-send-email-cbz@baozis.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Z5Cm0-0000vs-11 for xen-devel@lists.xenproject.org; Wed, 17 Jun 2015 12:48:56 +0000 In-Reply-To: <1434097969-16793-3-git-send-email-cbz@baozis.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Chen Baozi Cc: Julien Grall , xen-devel@lists.xenproject.org, Chen Baozi List-Id: xen-devel@lists.xenproject.org On Fri, 2015-06-12 at 16:32 +0800, Chen Baozi wrote: > From: Chen Baozi > > GICv3 restricts that the maximum number of CPUs in affinity 0 (one > cluster) is 16. (See the note of 'Bits[15:0]' in '5.7.29 ICC_SGI0R_EL1 > ICC_SGI1R_EL1 and ICC_ASGI1R_EL1, GICv3 Architecture Specification') > That is to say the upper 4 bits of affinity 0 is unused. Current > implementation considers that AFF0 is equal to vCPUID, which makes all > vCPUs in one cluster, limiting its number to 16. If we would like to > support more than 16 number of vCPU in one guest, we need to make use > of AFF1. Considering the unused upper 4 bits, we need to create a pair > of functions mapping the vCPUID and virtual affinity. > > Signed-off-by: Chen Baozi > Reviewed-by: Julien Grall Acked-by: Ian Campbell