- 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
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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

arch/x86/kernel/head_64.S

@@ -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