From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 5F5BD1A17F2 for ; Thu, 6 Aug 2015 20:16:31 +1000 (AEST) Received: from mail-pd0-f172.google.com (mail-pd0-f172.google.com [209.85.192.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id A36B81402A7 for ; Thu, 6 Aug 2015 20:16:29 +1000 (AEST) Received: by pdrg1 with SMTP id g1so30905874pdr.2 for ; Thu, 06 Aug 2015 03:16:28 -0700 (PDT) Subject: Re: [PATCH V2 2/6] powerpc/powernv: simplify the calculation of iov resource To: Wei Yang References: <20150731020148.GA6151@richard> <1438737903-10399-1-git-send-email-weiyang@linux.vnet.ibm.com> <1438737903-10399-3-git-send-email-weiyang@linux.vnet.ibm.com> <20150806045139.GB28524@gwshan> <55C32210.9090803@ozlabs.ru> <20150806094102.GB13055@richard> Cc: Gavin Shan , linuxppc-dev@ozlabs.org From: Alexey Kardashevskiy Message-ID: <55C333DB.4080406@ozlabs.ru> Date: Thu, 6 Aug 2015 20:15:55 +1000 MIME-Version: 1.0 In-Reply-To: <20150806094102.GB13055@richard> Content-Type: text/plain; charset=koi8-r; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 08/06/2015 07:41 PM, Wei Yang wrote: > On Thu, Aug 06, 2015 at 07:00:00PM +1000, Alexey Kardashevskiy wrote: >> On 08/06/2015 02:51 PM, Gavin Shan wrote: >>> On Wed, Aug 05, 2015 at 09:24:59AM +0800, Wei Yang wrote: >>>> The alignment of IOV BAR on PowerNV platform is the total size of the IOV >>>> BAR. No matter whether the IOV BAR is truncated or not, the total size >>>> could be calculated by (vfs_expanded * VF size). >>>> >>> >>> s/VF size/VF BAR size >>> >>> I think the changelog would be more explicit: >>> >>> The alignment of IOV BAR on PowerNV platform is the total size of the >>> IOV BAR, no matter whether the IOV BAR is extended with number of max >>> VFs or number of max PE number (256). The alignment can be calculated >>> by (vfs_expaned * VF_BAR_size). >> >> >> >> Is that really a PowerNV-specific requirement or it is valid for >> every platform (I suspect this is the case here)? >> > > Currently, it is PowerNV-specific. How is x86 different on this matter? Why would we need this extra alignment, not just VF's BAR alignment? >> >> Also, what is the exact meaning of "expanded" in @vfs_expanded? It is >> either 255 (if individual VF BARs are <= 64MB) or >> roundup_pow_of_two(total_vfs) (which is something like 4 or 16). What >> is expanded here? >> > > PF's IOV BAR original size is (VF BAR size * total_vfs). > > After expanding, the IOV BAR size is (VF BAR size * 256) or (VF BAR size * > roundup_pow_of_two(total_vfs)). Ufff, got it now. I'd store just an expanded IOV BAR size (not some magic VFs number) because this is what it actually is: pdn->vfs_expanded * align >> >>> >>>> This patch simplifies the pnv_pci_iov_resource_alignment() by removing the >>>> first case. >>>> >>>> Signed-off-by: Wei Yang >>> >>> Reviewed-by: Gavin Shan >>> >>>> --- >>>> arch/powerpc/platforms/powernv/pci-ioda.c | 14 +++++++++----- >>>> 1 file changed, 9 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c >>>> index 9b41dba..7192e62 100644 >>>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c >>>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c >>>> @@ -2987,12 +2987,16 @@ static resource_size_t pnv_pci_iov_resource_alignment(struct pci_dev *pdev, >>>> int resno) >>>> { >>>> struct pci_dn *pdn = pci_get_pdn(pdev); >>>> - resource_size_t align, iov_align; >>>> - >>>> - iov_align = resource_size(&pdev->resource[resno]); >>>> - if (iov_align) >>>> - return iov_align; >>>> + resource_size_t align; >>>> >>>> + /* >>>> + * On PowerNV platform, IOV BAR is mapped by M64 BAR to enable the >>>> + * SR-IOV. While from hardware perspective, the range mapped by M64 >>>> + * BAR should be size aligned. >>>> + * >>>> + * This function return the total IOV BAR size if expanded or just the >>>> + * individual size if not. >>>> + */ >>>> align = pci_iov_resource_size(pdev, resno); >>>> if (pdn->vfs_expanded) >>>> return pdn->vfs_expanded * align; >>>> -- >>>> 1.7.9.5 >>>> >>> >> >> >> -- >> Alexey > -- Alexey