Messages in this thread Patch in this message | | | Subject | Re: [PATCH] iommu/amd: Fix event counter availability check | From | Suravee Suthikulpanit <> | Date | Mon, 1 Jun 2020 22:10:09 +0700 |
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Alexander
On 6/1/20 4:01 PM, Alexander Monakov wrote: > On Mon, 1 Jun 2020, Suravee Suthikulpanit wrote: > >>> Moving init_iommu_perf_ctr just after iommu_flush_all_caches resolves >>> the issue. This is the earliest point in amd_iommu_init_pci where the >>> call succeeds on my laptop. >> >> According to your description, it should just need to be anywhere after the >> pci_enable_device() is called for the IOMMU device, isn't it? So, on your >> system, what if we just move the init_iommu_perf_ctr() here: > > No, this doesn't work, as I already said in the paragraph you are responding > to. See my last sentence in the quoted part. > > So the implication is init_device_table_dma together with subsequent cache > flush is also setting up something that is necessary for counters to be > writable. > > Alexander >
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:
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); }
/* -- 2.17.1 Thanks, Suravee
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