Commit 3ecacdbd authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov
Browse files

x86/head/64: Don't call verify_cpu() on starting APs 



The APs are not ready to handle exceptions when verify_cpu() is called
in secondary_startup_64().

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-69-joro@8bytes.org
parent 520d0308

arch/x86/include/asm/realmode.h

+1 −0
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ extern unsigned char startup_32_smp[]; 
extern unsigned char boot_gdt[];

#else

extern unsigned char secondary_startup_64[];

extern unsigned char secondary_startup_64_no_verify[];

#endif



static inline size_t real_mode_size_needed(void)

arch/x86/kernel/head_64.S

+12 −0
Original line number Diff line number Diff line
@@ -125,6 +125,18 @@ SYM_CODE_START(secondary_startup_64) 
	/* Sanitize CPU configuration */

	call verify_cpu



	/*

	 * The secondary_startup_64_no_verify entry point is only used by

	 * SEV-ES guests. In those guests the call to verify_cpu() would cause

	 * #VC exceptions which can not be handled at this stage of secondary

	 * CPU bringup.

	 *

	 * All non SEV-ES systems, especially Intel systems, need to execute

	 * verify_cpu() above to make sure NX is enabled.

	 */

SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)

	UNWIND_HINT_EMPTY



	/*

	 * Retrieve the modifier (SME encryption mask if SME is active) to be

	 * added to the initial pgdir entry that will be programmed into CR3.

arch/x86/realmode/init.c

+6 −0
Original line number Diff line number Diff line
@@ -46,6 +46,12 @@ static void sme_sev_setup_real_mode(struct trampoline_header *th) 
		th->flags |= TH_FLAGS_SME_ACTIVE;



	if (sev_es_active()) {

		/*

		 * Skip the call to verify_cpu() in secondary_startup_64 as it

		 * will cause #VC exceptions when the AP can't handle them yet.

		 */

		th->start = (u64) secondary_startup_64_no_verify;



		if (sev_es_setup_ap_jump_table(real_mode_header))

			panic("Failed to get/update SEV-ES AP Jump Table");

	}