From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932232AbcE0WYY (ORCPT ); Fri, 27 May 2016 18:24:24 -0400 Received: from mail-pa0-f68.google.com ([209.85.220.68]:34476 "EHLO mail-pa0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927AbcE0WYW (ORCPT ); Fri, 27 May 2016 18:24:22 -0400 From: Wei Yang To: joro@8bytes.org, robin.murphy@arm.com Cc: dwmw2@infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Wei Yang Subject: [PATCH v2 1/2] iommu/vt-d: reduce extra first level entry in iommu->domains Date: Fri, 27 May 2016 22:24:07 +0000 Message-Id: <1464387848-16942-2-git-send-email-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1464387848-16942-1-git-send-email-richard.weiyang@gmail.com> References: <1464387848-16942-1-git-send-email-richard.weiyang@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In commit <8bf478163e69> ("iommu/vt-d: Split up iommu->domains array"), it it splits iommu->domains in two levels. Each first level contains 256 entries of second level. In case of the ndomains is exact a multiple of 256, it would have one more extra first level entry for current implementation. This patch refines this calculation to reduce the extra first level entry when ndomains is exact a multiple of 256. Signed-off-by: Wei Yang --- drivers/iommu/intel-iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index d7fa268..1c8b587 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1634,7 +1634,7 @@ static int iommu_init_domains(struct intel_iommu *iommu) return -ENOMEM; } - size = ((ndomains >> 8) + 1) * sizeof(struct dmar_domain **); + size = DIV_ROUND_UP(ndomains, 256) * sizeof(struct dmar_domain **); iommu->domains = kzalloc(size, GFP_KERNEL); if (iommu->domains) { @@ -1699,7 +1699,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu) static void free_dmar_iommu(struct intel_iommu *iommu) { if ((iommu->domains) && (iommu->domain_ids)) { - int elems = (cap_ndoms(iommu->cap) >> 8) + 1; + int elems = DIV_ROUND_UP(cap_ndoms(iommu->cap), 256); int i; for (i = 0; i < elems; i++) -- 2.5.0