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Message-ID: <2cb8329655f5c753905812d951e212022a480475.1634318656.git.thomas.lendacky@amd.com> Date: Fri, 15 Oct 2021 12:24:16 -0500 From: Tom Lendacky <thomas.lendacky@....com> To: <linux-kernel@...r.kernel.org>, <x86@...nel.org> CC: 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>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, <stable@...r.kernel.org> Subject: [PATCH] x86/sme: Use #define USE_EARLY_PGTABLE_L5 in mem_encrypt_identity.c 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> --- arch/x86/mm/mem_encrypt_identity.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c index f8c612902038..3f0abb403340 100644 --- a/arch/x86/mm/mem_encrypt_identity.c +++ b/arch/x86/mm/mem_encrypt_identity.c @@ -27,6 +27,15 @@ #undef CONFIG_PARAVIRT_XXL #undef CONFIG_PARAVIRT_SPINLOCKS +/* + * This code runs before CPU feature bits are set. By default, the + * pgtable_l5_enabled() function uses bit X86_FEATURE_LA57 to determine if + * 5-level paging is active, so that won't work here. USE_EARLY_PGTABLE_L5 + * is provided to handle this situation and, instead, use a variable that + * has been set by the early boot code. + */ +#define USE_EARLY_PGTABLE_L5 + #include <linux/kernel.h> #include <linux/mm.h> #include <linux/mem_encrypt.h> -- 2.33.1
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