From: Mark Rutland <mark.rutland@arm.com>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Subject: Re: [boot-wrapper][PATCH] aarch64: Enable SPE for the non-secure world
Date: Wed, 12 Aug 2020 13:10:00 +0100 [thread overview]
Message-ID: <20200812121000.GE28154@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20200731094443.11564-1-alexandru.elisei@arm.com>
On Fri, Jul 31, 2020 at 10:44:43AM +0100, Alexandru Elisei wrote:
> MDCR_EL3.NSPB resets to an UNKNOWN value. Configure it to allow the
> profiling buffer to use non-secure memory and to permit direct register
> accesses from the non-secure world.
>
> So far, we haven't programmed MDCR_EL3 explicitly even though there are
> other fields which reset to an UNKNOWN value. The majority of those, when
> cleared, allow lower exception levels to use the features they control; for
> the other fields we don't have support yet. Reset the register to zero
> with the exception of MDCR_EL3.NSPB.
>
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> ---
> Tested on the model, with ARMv8.2 enabled and disabled (no SPE present).
Applied, thanks!
Mark.
>
> arch/aarch64/boot.S | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> index 74705cded338..f821b0175d4b 100644
> --- a/arch/aarch64/boot.S
> +++ b/arch/aarch64/boot.S
> @@ -55,6 +55,17 @@ _start:
>
> msr cptr_el3, xzr // Disable copro. traps to EL3
>
> + mov x0, xzr
> + mrs x1, id_aa64dfr0_el1
> + ubfx x1, x1, #32, #4
> + cbz x1, 1f
> +
> + // Enable SPE for the non-secure world.
> + ldr x1, =(0x3 << 12)
> + orr x0, x0, x1
> +
> +1: msr mdcr_el3, x0 // Disable traps to EL3
> +
> mrs x0, id_aa64pfr0_el1
> ubfx x0, x0, #32, #4 // SVE present?
> cbz x0, 1f // Skip SVE init if not
> --
> 2.28.0
>
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prev parent reply other threads:[~2020-08-12 12:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-31 9:44 [boot-wrapper][PATCH] aarch64: Enable SPE for the non-secure world Alexandru Elisei
2020-08-06 10:42 ` André Przywara
2020-08-12 12:10 ` Mark Rutland [this message]
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