Re: [PATCH 2/2] KVM: arm64: Don't map 'kvm_vgic_global_state' at EL2 with pKVM

[Marc Zyngier <maz@kernel.org>]

On Tue, 22 Oct 2024 15:40:16 +0100,
Will Deacon <will@kernel.org> wrote:
> 
> Now that 'kvm_vgic_global_state' is no longer needed for ICC_CTLR_EL1
> emulation on machines with a broken SEIS implementation, drop the
> pKVM hypervisor mapping of the page.
> 
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Oliver Upton <oliver.upton@linux.dev>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/kvm/hyp/nvhe/setup.c | 17 -----------------
>  1 file changed, 17 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
> index 174007f3fadd..8fec099c2775 100644
> --- a/arch/arm64/kvm/hyp/nvhe/setup.c
> +++ b/arch/arm64/kvm/hyp/nvhe/setup.c
> @@ -95,7 +95,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
>  {
>  	void *start, *end, *virt = hyp_phys_to_virt(phys);
>  	unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT;
> -	enum kvm_pgtable_prot prot;
>  	int ret, i;
>  
>  	/* Recreate the hyp page-table using the early page allocator */
> @@ -148,22 +147,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
>  	}
>  
>  	pkvm_create_host_sve_mappings();
> -
> -	/*
> -	 * Map the host sections RO in the hypervisor, but transfer the
> -	 * ownership from the host to the hypervisor itself to make sure they
> -	 * can't be donated or shared with another entity.
> -	 *
> -	 * The ownership transition requires matching changes in the host
> -	 * stage-2. This will be done later (see finalize_host_mappings()) once
> -	 * the hyp_vmemmap is addressable.
> -	 */
> -	prot = pkvm_mkstate(PAGE_HYP_RO, PKVM_PAGE_SHARED_OWNED);
> -	ret = pkvm_create_mappings(&kvm_vgic_global_state,
> -				   &kvm_vgic_global_state + 1, prot);
> -	if (ret)
> -		return ret;
> -
>  	return 0;
>  }

Maybe add a note indicating that nVHE/hVHE still have that particular
mapping via the rodata section?

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.