On Mon, May 20, 2019 at 10:56:59AM +1000, Nicholas Piggin wrote: > AIL=2 mode has no known users, so is not well tested or supported. > Disallow guests from selecting this mode because it may become > deprecated in future versions of the architecture. > > Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> Given that H_SET_MODE_RESOURCE_ADDR_TRANS_MODE gets punted to userspace (QEMU), why are we enforcing this here rather than in QEMU? If there is a reason to do this here rather than in QEMU, then the patch description should really comment on why we're rejecting AIL=1 as well as AIL=2. > --- > arch/powerpc/kvm/book3s_hv.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 36d16740748a..4295ccdbee26 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -784,6 +784,11 @@ static int kvmppc_h_set_mode(struct kvm_vcpu *vcpu, unsigned long mflags, > vcpu->arch.dawr = value1; > vcpu->arch.dawrx = value2; > return H_SUCCESS; > + case H_SET_MODE_RESOURCE_ADDR_TRANS_MODE: > + /* KVM does not support mflags=2 (AIL=2) */ > + if (mflags != 0 && mflags != 3) > + return H_UNSUPPORTED_FLAG_START; > + return H_TOO_HARD; > default: > return H_TOO_HARD; > } > -- > 2.20.1 Paul.
