Re: [PATCH v4 14/21] arm64: Honor VHE being disabled from the command-line

David Brazdil
2021-01-18T13:18:10Z

On Mon, Jan 18, 2021 at 09:45:26AM +0000, Marc Zyngier wrote:
> Finally we can check whether VHE is disabled on the command line,
> and not enable it if that's the user's wish.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>

> ---
> arch/arm64/kernel/hyp-stub.S | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
> index 59820f9b8522..bbab2148a2a2 100644
> --- a/arch/arm64/kernel/hyp-stub.S
> +++ b/arch/arm64/kernel/hyp-stub.S
> @@ -77,13 +77,24 @@ SYM_CODE_END(el1_sync)
> SYM_CODE_START_LOCAL(mutate_to_vhe)
> // Sanity check: MMU *must* be off
> mrs x0, sctlr_el2
> - tbnz x0, #0, 1f
> + tbnz x0, #0, 2f
>
> // Needs to be VHE capable, obviously
> mrs x0, id_aa64mmfr1_el1
> ubfx x0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4
> - cbz x0, 1f
> + cbz x0, 2f
>
> + // Check whether VHE is disabled from the command line
> + adr_l x1, id_aa64mmfr1_val
> + ldr x0, [x1]
> + adr_l x1, id_aa64mmfr1_mask
> + ldr x1, [x1]
super nit: There's a ldr_l macro

> + ubfx x0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4
> + ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
> + cbz x1, 1f
> + and x0, x0, x1
> + cbz x0, 2f
> +1:
> // Engage the VHE magic!
> mov_q x0, HCR_HOST_VHE_FLAGS
> msr hcr_el2, x0
> @@ -152,7 +163,7 @@ skip_spe:
> orr x0, x0, x1
> msr spsr_el1, x0
>
> -1: eret
> +2: eret
> SYM_CODE_END(mutate_to_vhe)
>
> .macro invalid_vector label
> --
> 2.29.2
>