Re: [PATCH v3 6/9] KVM: arm/arm64: Limit icache invalidation to prefetch aborts

[Andrew Jones <drjones@xxxxxxxxxx>]

On Mon, Oct 23, 2017 at 05:11:19PM +0100, Marc Zyngier wrote:
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 2174244f6317..0417c8e2a81c 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1292,7 +1292,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  			  unsigned long fault_status)
>  {
>  	int ret;
> -	bool write_fault, writable, hugetlb = false, force_pte = false;
> +	bool write_fault, exec_fault, writable, hugetlb = false, force_pte = false;
>  	unsigned long mmu_seq;
>  	gfn_t gfn = fault_ipa >> PAGE_SHIFT;
>  	struct kvm *kvm = vcpu->kvm;
> @@ -1304,7 +1304,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  	unsigned long flags = 0;
>  
>  	write_fault = kvm_is_write_fault(vcpu);
> -	if (fault_status == FSC_PERM && !write_fault) {
> +	exec_fault = kvm_vcpu_trap_is_iabt(vcpu);
> +	VM_BUG_ON(write_fault && exec_fault);

This VM_BUG_ON can never fire as long as kvm_is_write_fault() is
defined as

 {
   if (kvm_vcpu_trap_is_iabt(vcpu))
       return false;
   return kvm_vcpu_dabt_iswrite(vcpu);
 }

Thanks,
drew