Commit 9843231c authored by Tom Lendacky's avatar Tom Lendacky Committed by Ingo Molnar
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x86/boot/64: Move 5-level paging global variable assignments back 



Commit 63bed966 ("x86/startup_64: Defer assignment of 5-level paging
global variables") moved assignment of 5-level global variables to later
in the boot in order to avoid having to use RIP relative addressing in
order to set them. However, when running with 5-level paging and SME
active (mem_encrypt=on), the variables are needed as part of the page
table setup needed to encrypt the kernel (using pgd_none(), p4d_offset(),
etc.). Since the variables haven't been set, the page table manipulation
is done as if 4-level paging is active, causing the system to crash on
boot.

While only a subset of the assignments that were moved need to be set
early, move all of the assignments back into check_la57_support() so that
these assignments aren't spread between two locations. Instead of just
reverting the fix, this uses the new RIP_REL_REF() macro when assigning
the variables.

Fixes: 63bed966 ("x86/startup_64: Defer assignment of 5-level paging global variables")
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/2ca419f4d0de719926fd82353f6751f717590a86.1711122067.git.thomas.lendacky@amd.com
parent 4d0d7e78

arch/x86/kernel/head64.c

+7 −9
Original line number Diff line number Diff line
@@ -81,6 +81,13 @@ static inline bool check_la57_support(void) 
	if (!(native_read_cr4() & X86_CR4_LA57))

		return false;



	RIP_REL_REF(__pgtable_l5_enabled)	= 1;

	RIP_REL_REF(pgdir_shift)		= 48;

	RIP_REL_REF(ptrs_per_p4d)		= 512;

	RIP_REL_REF(page_offset_base)		= __PAGE_OFFSET_BASE_L5;

	RIP_REL_REF(vmalloc_base)		= __VMALLOC_BASE_L5;

	RIP_REL_REF(vmemmap_base)		= __VMEMMAP_BASE_L5;



	return true;

}
@@ -431,15 +438,6 @@ asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode 
				(__START_KERNEL & PGDIR_MASK)));

	BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);



	if (check_la57_support()) {

		__pgtable_l5_enabled	= 1;

		pgdir_shift		= 48;

		ptrs_per_p4d		= 512;

		page_offset_base	= __PAGE_OFFSET_BASE_L5;

		vmalloc_base		= __VMALLOC_BASE_L5;

		vmemmap_base		= __VMEMMAP_BASE_L5;

	}



	cr4_init_shadow();



	/* Kill off the identity-map trampoline */