From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934338AbcISMSi (ORCPT ); Mon, 19 Sep 2016 08:18:38 -0400 Received: from 8bytes.org ([81.169.241.247]:53265 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756055AbcISMSa (ORCPT ); Mon, 19 Sep 2016 08:18:30 -0400 Date: Mon, 19 Sep 2016 14:18:27 +0200 From: Joerg Roedel To: Xunlei Pang Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Woodhouse Subject: Re: [PATCH] iommu/vt-d: Fix the size calculation of pasid table Message-ID: <20160919121827.GB3541@8bytes.org> References: <1473648551-10025-1-git-send-email-xlpang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1473648551-10025-1-git-send-email-xlpang@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [Cc'ing David] On Mon, Sep 12, 2016 at 10:49:11AM +0800, Xunlei Pang wrote: > According to the vt-d spec, the size of pasid (state) entry is 8B > which equals 3 in power of 2, the number of pasid (state) entries > is (ecap_pss + 1) in power of 2. > > Thus the right size of pasid (state) table in power of 2 should be > ecap_pss(iommu->ecap) plus "1+3=4" other than 7. > > Signed-off-by: Xunlei Pang > --- > drivers/iommu/intel-svm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > index 8ebb353..cfa75c2 100644 > --- a/drivers/iommu/intel-svm.c > +++ b/drivers/iommu/intel-svm.c > @@ -39,7 +39,7 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu) > struct page *pages; > int order; > > - order = ecap_pss(iommu->ecap) + 7 - PAGE_SHIFT; > + order = ecap_pss(iommu->ecap) + 4 - PAGE_SHIFT; > if (order < 0) > order = 0; The patch seems to be correct, but I'll let David comment on it first. Joerg