On Tue, Feb 22, 2022 at 08:51:05AM -0800, Kalesh Singh wrote:
> Maps the stack pages in the flexible private VA range and allocates
> guard pages below the stack as unbacked VA space. The stack is aligned
> to twice its size to aid overflow detection (implemented in a subsequent
> patch in the series).
> 
> Signed-off-by: Kalesh Singh <kaleshsi...@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/setup.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
> index 27af337f9fea..69df21320b09 100644
> --- a/arch/arm64/kvm/hyp/nvhe/setup.c
> +++ b/arch/arm64/kvm/hyp/nvhe/setup.c
> @@ -105,11 +105,28 @@ static int recreate_hyp_mappings(phys_addr_t phys, 
> unsigned long size,
>               if (ret)
>                       return ret;
>  
> -             end = (void *)per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va;
> +             /*
> +              * Private mappings are allocated upwards from __io_map_base
> +              * so allocate the guard page first then the stack.
> +              */
> +             start = (void *)pkvm_alloc_private_va_range(PAGE_SIZE, 
> PAGE_SIZE);
> +             if (IS_ERR_OR_NULL(start))
> +                     return PTR_ERR(start);

As on a prior patch, this usage of PTR_ERR() pattern is wrong when the
ptr is NULL.

> +             /*
> +              * The stack is aligned to twice its size to facilitate overflow
> +              * detection.
> +              */
> +             end = (void *)per_cpu_ptr(&kvm_init_params, i)->stack_pa;
>               start = end - PAGE_SIZE;
> -             ret = pkvm_create_mappings(start, end, PAGE_HYP);
> -             if (ret)
> -                     return ret;
> +             start = (void 
> *)__pkvm_create_private_mapping((phys_addr_t)start,
> +                                     PAGE_SIZE, PAGE_SIZE * 2, PAGE_HYP);
> +             if (IS_ERR_OR_NULL(start))
> +                     return PTR_ERR(start);

Likewise.

Thanks,
Mark.

> +             end = start + PAGE_SIZE;
> +
> +             /* Update stack_hyp_va to end of the stack's private VA range */
> +             per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va = (unsigned 
> long) end;
>       }
>  
>       /*
> -- 
> 2.35.1.473.g83b2b277ed-goog
> 
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