From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Tiejun" Subject: Re: [PATCH] kvm: iommu: Add cond_resched to legacy device assignment code Date: Wed, 17 Dec 2014 09:38:57 +0800 Message-ID: <5490DEB1.30305@intel.com> References: <1418744846-12868-1-git-send-email-joro@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel To: Joerg Roedel , Gleb Natapov , Paolo Bonzini Return-path: Received: from mga11.intel.com ([192.55.52.93]:29030 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750932AbaLQBjC (ORCPT ); Tue, 16 Dec 2014 20:39:02 -0500 In-Reply-To: <1418744846-12868-1-git-send-email-joro@8bytes.org> Sender: kvm-owner@vger.kernel.org List-ID: On 2014/12/16 23:47, Joerg Roedel wrote: > From: Joerg Roedel > > When assigning devices to large memory guests (>=128GB guest > memory in the failure case) the functions to create the > IOMMU page-tables for the whole guest might run for a very > long time. On non-preemptible kernels this might cause > Soft-Lockup warnings. Fix these by adding a cond_resched() > to the mapping and unmapping loops. > > Signed-off-by: Joerg Roedel > --- > virt/kvm/iommu.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c > index c1e6ae9..ac427e8 100644 > --- a/virt/kvm/iommu.c > +++ b/virt/kvm/iommu.c This file is already gone after one latest commit c274e03af705, "kvm: x86: move assigned-dev.c and iommu.c to arch/x86/" is introduced, so you need to pull your tree firstly :) Tiejun > @@ -137,7 +137,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot) > > gfn += page_size >> PAGE_SHIFT; > > - > + cond_resched(); > } > > return 0; > @@ -311,6 +311,8 @@ static void kvm_iommu_put_pages(struct kvm *kvm, > kvm_unpin_pages(kvm, pfn, unmap_pages); > > gfn += unmap_pages; > + > + cond_resched(); > } > } > >