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Date:   Mon, 1 Jun 2020 19:09:29 +0300 (MSK)
From:   Alexander Monakov <amonakov@ispras.ru>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
cc:     linux-kernel@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
        iommu@lists.linux-foundation.org
Subject: Re: [PATCH] iommu/amd: Fix event counter availability check
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Message-ID: <alpine.LNX.2.20.13.2006011903210.16067@monopod.intra.ispras.ru>
References: <20200529200738.1923-1-amonakov@ispras.ru> <56761139-f794-39b1-4dfa-dfc05fbe5f60@amd.com> <alpine.LNX.2.20.13.2006011132530.16067@monopod.intra.ispras.ru> <dba1e37a-1ed7-ef7f-7252-2ebd1d6bde8c@amd.com>
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> Instead of blindly moving the code around to a spot that would just work,
> I am trying to understand what might be required here. In this case,
> the init_device_table_dma()should not be needed. I suspect it's the IOMMU
> invalidate all command that's also needed here.
> 
> I'm also checking with the HW and BIOS team. Meanwhile, could you please give
> the following change a try:

Yes, this also fixes the problem for me.
Alexander

> 
> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> index 5b81fd16f5fa..b07458cc1b0b 100644
> --- a/drivers/iommu/amd_iommu_init.c
> +++ b/drivers/iommu/amd_iommu_init.c
> @@ -1875,6 +1875,8 @@ static int __init amd_iommu_init_pci(void)
>                 ret = iommu_init_pci(iommu);
>                 if (ret)
>                         break;
> +               iommu_flush_all_caches(iommu);
> +               init_iommu_perf_ctr(iommu);
>         }
> 
>         /*