From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laura Abbott Subject: Re: Warning from AMD IOMMU performance counters Date: Tue, 23 Feb 2016 09:26:18 -0800 Message-ID: <56CC963A.1080607@redhat.com> References: <56C798B8.6080009@redhat.com> <56CA69C7.3050508@iommu.org> <56CBB789.4020704@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56CBB789.4020704@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Wan Zongshun , Joerg Roedel , Suravee.Suthikulpanit@amd.com Cc: iommu@lists.linux-foundation.org, Linux Kernel Mailing List List-Id: iommu@lists.linux-foundation.org On 02/22/2016 05:36 PM, Laura Abbott wrote: > On 02/21/2016 05:52 PM, Wan Zongshun wrote: >> >> >> -------- Original Message -------- >>> Hi, >>> >>> Since about 4.4, we've been seeing reports of this warning on every boot >>> from some users: >>> >>> WARNING: CPU: 2 PID: 1 at drivers/iommu/amd_iommu_init.c:2301 >>> amd_iommu_pc_get_set_reg_val+0xa8/0xe0() >>> Modules linked in: >>> CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.4.2-300.fc23.x86_64 #1 >>> Hardware name: Hewlett-Packard HP EliteBook 755 G2/221C, BIOS M84 Ver. >>> 01.10 10/20/2015 >>> 0000000000000000 0000000026124b43 ffff88042d687d20 ffffffff813b0c9f >>> 0000000000000000 ffff88042d687d58 ffffffff810a2f12 ffff88042f014800 >>> 0000000000000040 0000000000000000 ffffffff81d6c73d 0000000000000000 >>> Call Trace: >>> [] dump_stack+0x44/0x55 >>> [] warn_slowpath_common+0x82/0xc0 >>> [] ? memblock_find_dma_reserve+0x16a/0x16a >>> [] warn_slowpath_null+0x1a/0x20 >>> [] amd_iommu_pc_get_set_reg_val+0xa8/0xe0 >>> [] iommu_go_to_state+0x4d6/0x1384 >>> [] ? kvasprintf+0x7a/0xa0 >>> [] ? memblock_find_dma_reserve+0x16a/0x16a >>> [] amd_iommu_init+0x13/0x201 >>> [] pci_iommu_init+0x12/0x3c >>> [] do_one_initcall+0xb3/0x200 >>> [] ? parse_args+0x295/0x4b0 >>> [] kernel_init_freeable+0x189/0x223 >>> [] ? rest_init+0x80/0x80 >>> [] kernel_init+0xe/0xe0 >>> [] ret_from_fork+0x3f/0x70 >>> [] ? rest_init+0x80/0x80 >>> >>> Full bugzilla https://bugzilla.redhat.com/show_bug.cgi?id=1310258 >>> >>> Any idea what might be causing this spew? >> >> I also see this warning. >> >> Suravee's the one of this patch series might be fix this issue, you can try it. >> >> [PATCH V4 0/6] perf/amd/iommu: Enable multi-IOMMU support >> >> > > That patch had other dependencies. I brought what I thought were enough of > them in to at least compile for the reporter to test (perf_event changes > from Borislav Petkov). Apparently the kernel doesn't boot with the series > so suspect there is an integration issue somewhere. I'm going to see if > I can more information from the reporter about what exactly went wrong > to see if I need more dependencies. > It was an issue with build signing on the testers machine. Once that was fixed it was confirmed that the patches did fix the issue. > It would be nice to get a single patch which could be applied to stable. > Tainting the kernel immediately on bootup makes sorting through problems > more difficult. > > Thanks, > Laura > >