From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wan Zongshun <vw-6ukY98dZOFrYtjvyW6yDsg@public.gmane.org>
Subject: Re: Warning from AMD IOMMU performance counters
Date: Mon, 22 Feb 2016 09:52:07 +0800
Message-ID: <56CA69C7.3050508@iommu.org>
References: <56C798B8.6080009@redhat.com>
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-------- 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:
>   [<ffffffff813b0c9f>] dump_stack+0x44/0x55
>   [<ffffffff810a2f12>] warn_slowpath_common+0x82/0xc0
>   [<ffffffff81d6c73d>] ? memblock_find_dma_reserve+0x16a/0x16a
>   [<ffffffff810a305a>] warn_slowpath_null+0x1a/0x20
>   [<ffffffff814d3f48>] amd_iommu_pc_get_set_reg_val+0xa8/0xe0
>   [<ffffffff81dafda7>] iommu_go_to_state+0x4d6/0x1384
>   [<ffffffff813c02ea>] ? kvasprintf+0x7a/0xa0
>   [<ffffffff81d6c73d>] ? memblock_find_dma_reserve+0x16a/0x16a
>   [<ffffffff81db0cbd>] amd_iommu_init+0x13/0x201
>   [<ffffffff81d6c74f>] pci_iommu_init+0x12/0x3c
>   [<ffffffff81002123>] do_one_initcall+0xb3/0x200
>   [<ffffffff810c0935>] ? parse_args+0x295/0x4b0
>   [<ffffffff81d621c8>] kernel_init_freeable+0x189/0x223
>   [<ffffffff8178dc00>] ? rest_init+0x80/0x80
>   [<ffffffff8178dc0e>] kernel_init+0xe/0xe0
>   [<ffffffff81799c8f>] ret_from_fork+0x3f/0x70
>   [<ffffffff8178dc00>] ? 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


>
> Thanks,
> Laura
> _______________________________________________
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