[PATCH v2 2/2] KVM: arm64: Fix exclusive limit for IPA size

[Auger Eric]

Hi Marc,

On 3/10/21 11:42 AM, Marc Zyngier wrote:
> When registering a memslot, we check the size and location of that
> memslot against the IPA size to ensure that we can provide guest
> access to the whole of the memory.
> 
> Unfortunately, this check rejects memslot that end-up at the exact
> limit of the addressing capability for a given IPA size. For example,
> it refuses the creatrion of a 2GB memslot at 0x8000000 with a 32bit
creation
> IPA space.
> 
> Fix it by relaxing the check to accept a memslot reaching the
> limit of the IPA space.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
stable + Fixes?
> ---
>  arch/arm64/kvm/mmu.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 77cb2d28f2a4..8711894db8c2 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1312,8 +1312,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
>  	 * Prevent userspace from creating a memory region outside of the IPA
>  	 * space addressable by the KVM guest IPA space.
>  	 */
> -	if (memslot->base_gfn + memslot->npages >=
> -	    (kvm_phys_size(kvm) >> PAGE_SHIFT))
> +	if ((memslot->base_gfn + memslot->npages) > (kvm_phys_size(kvm) >> PAGE_SHIFT))
>  		return -EFAULT;
>  
>  	mmap_read_lock(current->mm);
> 
Reviewed-by: Eric Auger <eric.auger at redhat.com>

Thanks

Eric