linux-kernel - [PATCH 1/2] x86/boot/64: Apply encryption mask to 5-level pagetable update

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Date: Fri, 22 Mar 2024 10:41:06 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC: Borislav Petkov <bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>, Ingo
 Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Ard
 Biesheuvel <ardb@...nel.org>
Subject: [PATCH 1/2] x86/boot/64: Apply encryption mask to 5-level pagetable update

When running with 5-level page tables, the kernel mapping PGD entry is
updated to point to the P4D table. The assignment uses _PAGE_TABLE_NOENC,
which, when SME is active (mem_encrypt=on), results in a page table
entry without the encryption mask set, causing the system to crash on
boot.

Change the assignment to use _PAGE_TABLE instead of _PAGE_TABLE_NOENC so
that the encryption mask is set for the PGD entry.

Fixes: 533568e06b15 ("x86/boot/64: Use RIP_REL_REF() to access early_top_pgt[]")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/head64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 212e8e06aeba..7d2eb035b6a3 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -175,7 +175,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
 		p4d = (p4dval_t *)&RIP_REL_REF(level4_kernel_pgt);
 		p4d[MAX_PTRS_PER_P4D - 1] += load_delta;
 
-		pgd[pgd_index(__START_KERNEL_map)] = (pgdval_t)p4d | _PAGE_TABLE_NOENC;
+		pgd[pgd_index(__START_KERNEL_map)] = (pgdval_t)p4d | _PAGE_TABLE;
 	}
 
 	RIP_REL_REF(level3_kernel_pgt)[PTRS_PER_PUD - 2].pud += load_delta;
-- 
2.43.2