Commit 4c605260 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_urgent_for_v6.4_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fix from Borislav Petkov:

 - Set up the kernel CS earlier in the boot process in case EFI boots
   the kernel after bypassing the decompressor and the CS descriptor
   used ends up being the EFI one which is not mapped in the identity
   page table, leading to early SEV/SNP guest communication exceptions
   resulting in the guest crashing

* tag 'x86_urgent_for_v6.4_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/head/64: Switch to KERNEL_CS as soon as new GDT is installed
parents 65d7ca59 a37f2699

arch/x86/kernel/head_64.S

+9 −9
Original line number Diff line number Diff line
@@ -77,6 +77,15 @@ SYM_CODE_START_NOALIGN(startup_64) 
	call	startup_64_setup_env

	popq	%rsi



	/* Now switch to __KERNEL_CS so IRET works reliably */

	pushq	$__KERNEL_CS

	leaq	.Lon_kernel_cs(%rip), %rax

	pushq	%rax

	lretq



.Lon_kernel_cs:

	UNWIND_HINT_END_OF_STACK



#ifdef CONFIG_AMD_MEM_ENCRYPT

	/*

	 * Activate SEV/SME memory encryption if supported/enabled. This needs to
@@ -90,15 +99,6 @@ SYM_CODE_START_NOALIGN(startup_64) 
	popq	%rsi

#endif



	/* Now switch to __KERNEL_CS so IRET works reliably */

	pushq	$__KERNEL_CS

	leaq	.Lon_kernel_cs(%rip), %rax

	pushq	%rax

	lretq



.Lon_kernel_cs:

	UNWIND_HINT_END_OF_STACK



	/* Sanitize CPU configuration */

	call verify_cpu