iommu/amd: Use 4K page for completion wait write-back semaphore
IOMMU SNP support requires the completion wait write-back semaphore to be implemented using a 4K-aligned page, where the page address is to be programmed into the newly introduced MMIO base/range registers. This new scheme uses a per-iommu atomic variable to store the current semaphore value, which is incremented for every completion wait command. Since this new scheme is also compatible with non-SNP mode, generalize the driver to use 4K page for completion-wait semaphore in both modes. Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Link: https://lore.kernel.org/r/20200923121347.25365-2-suravee.suthikulpanit@amd.com Signed-off-by: Joerg Roedel <jroedel@suse.de>