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arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is negative

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For CPUs that have ID_AA64MMFR4_EL1.E2H0 as negative, it is important
to avoid the boot path that sets HCR_EL2.E2H=0. Fortunately, we
already have this path to cope with fruity CPUs.

Tweak init_el2 to look at ID_AA64MMFR4_EL1.E2H0 first.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20240122181344.258974-8-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2024-01-22 18:13:41 +00:00 • committed by Oliver Upton
parent da9af5071b
commit 3944382fa6
1 changed files with 15 additions and 8 deletions
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23
arch/arm64/kernel/head.S
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@ -584,25 +584,32 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
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
* compliant with the architecture? Absolutely not!
* Compliant CPUs advertise their VHE-onlyness with
* ID_AA64MMFR4_EL1.E2H0 < 0. HCR_EL2.E2H can be
* RES1 in that case.
*
* Fruity CPUs seem to have HCR_EL2.E2H set to RES1, but
* don't advertise it (they predate this relaxation).
*/
mrs_s x0, SYS_ID_AA64MMFR4_EL1
ubfx x0, x0, #ID_AA64MMFR4_EL1_E2H0_SHIFT, #ID_AA64MMFR4_EL1_E2H0_WIDTH
tbnz x0, #(ID_AA64MMFR4_EL1_E2H0_SHIFT + ID_AA64MMFR4_EL1_E2H0_WIDTH - 1), 1f
mrs x0, hcr_el2
and x0, x0, #HCR_E2H
cbz x0, 1f
cbz x0, 2f
1:
/* Set a sane SCTLR_EL1, the VHE way */
pre_disable_mmu_workaround
msr_s SYS_SCTLR_EL12, x1
mov x2, #BOOT_CPU_FLAG_E2H
b 2f
b 3f
1:
2:
pre_disable_mmu_workaround
msr sctlr_el1, x1
mov x2, xzr
2:
3:
__init_el2_nvhe_prepare_eret
mov w0, #BOOT_CPU_MODE_EL2