Commit ae4b7e38 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

arm64: Allow sticky E2H when entering EL1 



For CPUs that have the unfortunate mis-feature to be stuck in
VHE mode, we perform a funny dance where we completely shortcut
the normal boot process to enable VHE and run the kernel at EL2,
and only then start booting the kernel.

Not only this is pretty ugly, but it means that the EL2 finalisation
occurs before we have processed the sysreg override.

Instead, start executing the kernel as if it was an EL1 guest and
rely on the normal EL2 finalisation to go back to EL2.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220630160500.1536744-4-maz@kernel.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent b65e411d

arch/arm64/kernel/head.S

+10 −24
Original line number Diff line number Diff line
@@ -511,6 +511,8 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL) 
	msr	vbar_el2, x0

	isb



	mov_q	x1, INIT_SCTLR_EL1_MMU_OFF



	/*

	 * Fruity CPUs seem to have HCR_EL2.E2H set to RES1,

	 * making it impossible to start in nVHE mode. Is that
@@ -520,35 +522,19 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL) 
	and	x0, x0, #HCR_E2H

	cbz	x0, 1f



	/* Switching to VHE requires a sane SCTLR_EL1 as a start */

	mov_q	x0, INIT_SCTLR_EL1_MMU_OFF

	msr_s	SYS_SCTLR_EL12, x0



	/*

	 * Force an eret into a helper "function", and let it return

	 * to our original caller... This makes sure that we have

	 * initialised the basic PSTATE state.

	 */

	mov	x0, #INIT_PSTATE_EL2

	msr	spsr_el1, x0

	adr	x0, __cpu_stick_to_vhe

	msr	elr_el1, x0

	eret

	/* Set a sane SCTLR_EL1, the VHE way */

	msr_s	SYS_SCTLR_EL12, x1

	mov	x2, #BOOT_CPU_FLAG_E2H

	b	2f



1:

	mov_q	x0, INIT_SCTLR_EL1_MMU_OFF

	msr	sctlr_el1, x0



	msr	sctlr_el1, x1

	mov	x2, xzr

2:

	msr	elr_el2, lr

	mov	w0, #BOOT_CPU_MODE_EL2

	orr	x0, x0, x2

	eret



__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)



/*