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

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