Commit b65e411d authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

arm64: Save state of HCR_EL2.E2H before switch to EL1 



As we're about to switch the way E2H-stuck CPUs boot, save
the boot CPU E2H state as a flag tied to the boot mode
that can then be checked by the idreg override code.

This allows us to replace the is_kernel_in_hyp_mode() check
with a simple comparison with this state, even when running
at EL1. Note that this flag isn't saved in __boot_cpu_mode,
and is only kept in a register in the assembly code.

Use with caution.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220630160500.1536744-3-maz@kernel.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 7ddb0c3d

arch/arm64/include/asm/virt.h

+7 −0
Original line number Diff line number Diff line
@@ -49,6 +49,13 @@ 
#define BOOT_CPU_MODE_EL1	(0xe11)

#define BOOT_CPU_MODE_EL2	(0xe12)



/*

 * Flags returned together with the boot mode, but not preserved in

 * __boot_cpu_mode. Used by the idreg override code to work out the

 * boot state.

 */

#define BOOT_CPU_FLAG_E2H	BIT_ULL(32)



#ifndef __ASSEMBLY__



#include <asm/ptrace.h>

arch/arm64/kernel/head.S

+5 −2
Original line number Diff line number Diff line
@@ -457,6 +457,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) 
	bl	kasan_early_init

#endif

	mov	x0, x22				// pass FDT address in x0

	mov	x1, x20				// pass the full boot status

	bl	init_feature_override		// Parse cpu feature overrides

	mov	x0, x20

	bl	finalise_el2			// Prefer VHE if possible
@@ -479,8 +480,9 @@ SYM_FUNC_END(__primary_switched) 
 * Since we cannot always rely on ERET synchronizing writes to sysregs (e.g. if

 * SCTLR_ELx.EOS is clear), we place an ISB prior to ERET.

 *

 * Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in w0 if

 * booted in EL1 or EL2 respectively.

 * Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in x0 if

 * booted in EL1 or EL2 respectively, with the top 32 bits containing

 * potential context flags. These flags are *not* stored in __boot_cpu_mode.

 */

SYM_FUNC_START(init_kernel_el)

	mrs	x0, CurrentEL
@@ -545,6 +547,7 @@ __cpu_stick_to_vhe: 
	mov	x0, #HVC_FINALISE_EL2

	hvc	#0

	mov	x0, #BOOT_CPU_MODE_EL2

	orr	x0, x0, #BOOT_CPU_FLAG_E2H

	ret

SYM_FUNC_END(init_kernel_el)

arch/arm64/kernel/idreg-override.c

+8 −3
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
#define FTR_ALIAS_NAME_LEN	30

#define FTR_ALIAS_OPTION_LEN	116



static u64 __boot_status __initdata;



struct ftr_set_desc {

	char 				name[FTR_DESC_NAME_LEN];

	struct arm64_ftr_override	*override;
@@ -37,7 +39,8 @@ static bool __init mmfr1_vh_filter(u64 val) 
	 * the user was trying to force nVHE on us, proceed with

	 * attitude adjustment.

	 */

	return !(is_kernel_in_hyp_mode() && val == 0);

	return !(__boot_status == (BOOT_CPU_FLAG_E2H | BOOT_CPU_MODE_EL2) &&

		 val == 0);

}



static const struct ftr_set_desc mmfr1 __initconst = {
@@ -229,9 +232,9 @@ static __init void parse_cmdline(const void *fdt) 
}



/* Keep checkers quiet */

void init_feature_override(const void *fdt);

void init_feature_override(const void *fdt, u64 boot_status);



asmlinkage void __init init_feature_override(const void *fdt)

asmlinkage void __init init_feature_override(const void *fdt, u64 boot_status)

{

	int i;
@@ -242,6 +245,8 @@ asmlinkage void __init init_feature_override(const void *fdt) 
		}

	}



	__boot_status = boot_status;



	parse_cmdline(fdt);



	for (i = 0; i < ARRAY_SIZE(regs); i++) {