On Fri, Oct 15, 2021 at 12:24:16PM -0500, Tom Lendacky wrote:
When runtime support for converting between 4-level and 5-level pagetables was added to the kernel, the SME code that built pagetables was updated to use the pagetable functions, e.g. p4d_offset(), etc., in order to simplify the code. However, the use of the pagetable functions in early boot code requires the use of the USE_EARLY_PGTABLE_L5 #define in order to ensure that proper definition of pgtable_l5_enabled() is used.
Without the #define, pgtable_l5_enabled() is #defined as cpu_feature_enabled(X86_FEATURE_LA57). In early boot, the CPU features have not yet been discovered and populated, so pgtable_l5_enabled() will return false even when 5-level paging is enabled. This causes the SME code to always build 4-level pagetables to perform the in-place encryption. If 5-level paging is enabled, switching to the SME pagetables results in a page-fault that kills the boot.
Adding the #define results in pgtable_l5_enabled() using the __pgtable_l5_enabled variable set in early boot and the SME code building pagetables for the proper paging level.
Cc: stable@vger.kernel.org # 4.18.x Fixes: aad983913d77 ("x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()") Signed-off-by: Tom Lendacky thomas.lendacky@amd.com
Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com