[PATCH 0/3] handle init errors more gracefully in amd_iommu

[Kevin Mitchell <kevmitch@arista.com>]

This series makes error handling more robust in the amd_iommu init
code. It was initially motivated by problematic firmware that does not
set up the physical address of the iommu. This led to a NULL dereference
panic when iommu_disable was called during cleanup.

While the first patch is sufficient to avoid the panic, the subsequent
two move the cleanup closer to the actual error and avoid calling the
cleanup code twice when amd_iommu=off is specified on the command line.

I have tested this series on a variety of AMD CPUs with firmware
exhibiting the issue. I have additionally tested on platforms where the
firmware has been fixed. I tried both with and without amd_iommu=off. I
have also tested on older CPUs where no IOMMU is detected and even one
where the GART driver ends up running.

Thanks,

Kevin

Kevin Mitchell (3):
  iommu/amd: make iommu_disable safer
  iommu/amd: move gart fallback to amd_iommu_init
  iommu/amd: only free resources once on init error

 drivers/iommu/amd_iommu_init.c | 45 ++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 21 deletions(-)

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2.20.1