Commit 0c93df96 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

arm64: Initialise as nVHE before switching to VHE 



As we are aiming to be able to control whether we enable VHE or
not, let's always drop down to EL1 first, and only then upgrade
to VHE if at all possible.

This means that if the kernel is booted at EL2, we always start
with a nVHE init, drop to EL1 to initialise the the kernel, and
only then upgrade the kernel EL to EL2 if possible (the process
is obviously shortened for secondary CPUs).

The resume path is handled similarly to a secondary CPU boot.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Acked-by: default avatarDavid Brazdil <dbrazdil@google.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-6-maz@kernel.org


[will: Avoid calling switch_to_vhe twice on kaslr path]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent f3591822

arch/arm64/kernel/head.S

+2 −36
Original line number Diff line number Diff line
@@ -447,6 +447,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) 
	ret					// to __primary_switch()

0:

#endif

	bl	switch_to_vhe			// Prefer VHE if possible

	add	sp, sp, #16

	mov	x29, #0

	mov	x30, #0
@@ -493,42 +494,6 @@ SYM_INNER_LABEL(init_el1, SYM_L_LOCAL) 
	eret



SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)

#ifdef CONFIG_ARM64_VHE

	/*

	 * Check for VHE being present. x2 being non-zero indicates that we

	 * do have VHE, and that the kernel is intended to run at EL2.

	 */

	mrs	x2, id_aa64mmfr1_el1

	ubfx	x2, x2, #ID_AA64MMFR1_VHE_SHIFT, #4

#else

	mov	x2, xzr

#endif

	cbz	x2, init_el2_nvhe



	/*

	 * When VHE _is_ in use, EL1 will not be used in the host and

	 * requires no configuration, and all non-hyp-specific EL2 setup

	 * will be done via the _EL1 system register aliases in __cpu_setup.

	 */

	mov_q	x0, HCR_HOST_VHE_FLAGS

	msr	hcr_el2, x0

	isb



	init_el2_state vhe



	isb



	mov_q	x0, INIT_PSTATE_EL2

	msr	spsr_el2, x0

	msr	elr_el2, lr

	mov	w0, #BOOT_CPU_MODE_EL2

	eret



SYM_INNER_LABEL(init_el2_nvhe, SYM_L_LOCAL)

	/*

	 * When VHE is not in use, early init of EL2 and EL1 needs to be

	 * done here.

	 */

	mov_q	x0, INIT_SCTLR_EL1_MMU_OFF

	msr	sctlr_el1, x0
@@ -623,6 +588,7 @@ SYM_FUNC_START_LOCAL(secondary_startup) 
	/*

	 * Common entry point for secondary CPUs.

	 */

	bl	switch_to_vhe

	bl	__cpu_secondary_check52bitva

	bl	__cpu_setup			// initialise processor

	adrp	x1, swapper_pg_dir

arch/arm64/kernel/hyp-stub.S

+24 −0
Original line number Diff line number Diff line
@@ -190,3 +190,27 @@ SYM_FUNC_START(__hyp_reset_vectors) 
	hvc	#0

	ret

SYM_FUNC_END(__hyp_reset_vectors)



/*

 * Entry point to switch to VHE if deemed capable

 */

SYM_FUNC_START(switch_to_vhe)

#ifdef CONFIG_ARM64_VHE

	// Need to have booted at EL2

	adr_l	x1, __boot_cpu_mode

	ldr	w0, [x1]

	cmp	w0, #BOOT_CPU_MODE_EL2

	b.ne	1f



	// and still be at EL1

	mrs	x0, CurrentEL

	cmp	x0, #CurrentEL_EL1

	b.ne	1f



	// Turn the world upside down

	mov	x0, #HVC_VHE_RESTART

	hvc	#0

1:

#endif

	ret

SYM_FUNC_END(switch_to_vhe)

arch/arm64/kernel/sleep.S

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ SYM_FUNC_END(__cpu_suspend_enter) 
	.pushsection ".idmap.text", "awx"

SYM_CODE_START(cpu_resume)

	bl	init_kernel_el

	bl	switch_to_vhe

	bl	__cpu_setup

	/* enable the MMU early - so we can access sleep_save_stash by va */

	adrp	x1, swapper_pg_dir