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Message-ID: <20211015204338.64p3a7vwylqacbfm@black.fi.intel.com> Date: Fri, 15 Oct 2021 23:43:38 +0300 From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> To: Tom Lendacky <thomas.lendacky@....com> Cc: linux-kernel@...r.kernel.org, x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, stable@...r.kernel.org Subject: Re: [PATCH] x86/sme: Use #define USE_EARLY_PGTABLE_L5 in mem_encrypt_identity.c 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@...r.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@....com> Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com> -- Kirill A. Shutemov
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