iommu/amd: Fix performance counter initialization
Certain AMD platforms enable power gating feature for IOMMU PMC, which prevents the IOMMU driver from updating the counter while trying to validate the PMC functionality in the init_iommu_perf_ctr(). This results in disabling PMC support and the following error message: "AMD-Vi: Unable to read/write to IOMMU perf counter" To workaround this issue, disable power gating temporarily by programming the counter source to non-zero value while validating the counter, and restore the prior state afterward. Signed-off-by:Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Tested-by:
Tj (Elloe Linux) <ml.linux@elloe.vision> Link: https://lore.kernel.org/r/20210208122712.5048-1-suravee.suthikulpanit@amd.com Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201753 Signed-off-by:
Joerg Roedel <jroedel@suse.de>
parent
89c9a09c
Please register or sign in to comment