Re: [Minios-devel] [UNIKRAFT RFC PATCH 2/5] plat/kvm: arm64: Enable the fp/simd at the starting point

[Julien Grall <julien@xxxxxxx>]

Hi,

On 19/12/2019 14:27, Jia He wrote:
> Write the sys reg to enable the fp/simd feature, otherwise it will
> cause floating point/simd exception when touching q0-q31.
In your first patch you say FPSIMD will be available for application 
only. But here, you will allow Unikraft itself to use it.
So don't you want to turn this only when jumping to the application code?

> Signed-off-by: Jia He <justin.he@xxxxxxx>
> ---
>   plat/kvm/arm/entry64.S | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/plat/kvm/arm/entry64.S b/plat/kvm/arm/entry64.S
> index 359a310..1e32268 100644
> --- a/plat/kvm/arm/entry64.S
> +++ b/plat/kvm/arm/entry64.S
> @@ -36,6 +36,7 @@
>   #include <kvm-arm/mm.h>
>   #include <arm/cpu_defs.h>
>   #include <uk/plat/common/sections.h>
> +#include <uk/config.h>
>   
>   .global page_table_size
>   .data
> @@ -49,6 +50,13 @@ page_table_size:
>   
>   .text
>   ENTRY(_libkvmplat_entry)
> +#ifdef CONFIG_FLOAT_POINT
> +       /* Enable fp/simd support */
> +       ldr        x0, =(3 << 20)
> +       msr        cpacr_el1, x0
> +       isb
> +#endif
> +
>         /* Calculate the image size */
>         ldr x25, =_dtb
>         ldr x26, =_end
--
Julien Grall

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