On Thu, 14 Mar 2024 20:24:31 +0000,
Pierre-Clément Tosi <ptosi@xxxxxxxxxx> wrote:
>
> Introduce handlers for EL2{t,h} synchronous exceptions distinct from
> handlers for other "invalid" exceptions when running with the nVHE host
> vector. This will allow a future patch to handle CFI (synchronous)
> errors without affecting other classes of exceptions.
>
> Remove superfluous SP overflow check from the non-synchronous
> handlers.
Why are they superfluous? Because we are panic'ing? Detecting a stack
overflow is pretty valuable in any circumstances.
>
> Signed-off-by: Pierre-Clément Tosi <ptosi@xxxxxxxxxx>
> ---
> arch/arm64/kvm/hyp/nvhe/host.S | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
> index 27c989c4976d..1b9111c2b480 100644
> --- a/arch/arm64/kvm/hyp/nvhe/host.S
> +++ b/arch/arm64/kvm/hyp/nvhe/host.S
> @@ -183,7 +183,7 @@ SYM_FUNC_END(__host_hvc)
> .endif
> .endm
>
> -.macro invalid_host_el2_vect
> +.macro host_el2_sync_vect
> .align 7
>
> /*
> @@ -221,6 +221,11 @@ SYM_FUNC_END(__host_hvc)
> b __hyp_do_panic
> .endm
>
> +.macro invalid_host_el2_vect
> + .align 7
> + b __hyp_panic
> +.endm
> +
> /*
> * The host vector does not use an ESB instruction in order to avoid consuming
> * SErrors that should only be consumed by the host. Guest entry is deferred by
> @@ -233,12 +238,12 @@ SYM_FUNC_END(__host_hvc)
> */
> .align 11
> SYM_CODE_START(__kvm_hyp_host_vector)
> - invalid_host_el2_vect // Synchronous EL2t
> + host_el2_sync_vect // Synchronous EL2t
The real question is: under which circumstances would running with
SP_EL0 be valid? I cannot see good reason for it.
M.
--
Without deviation from the norm, progress is not possible.
