If the nested hypervisor has no access to a facility because it has been disabled by the host, it should also not be able to see the Hypervisor Facility Unavailable that arises from one of its guests trying to access the facility.
This patch turns a HFU that happened in L2 into a Hypervisor Emulation Assistance interrupt and forwards it to L1 for handling. The ones that happened because L1 explicitly disabled the facility for L2 are still let through, along with the corresponding Cause bits in the HFSCR. Signed-off-by: Fabiano Rosas <faro...@linux.ibm.com> Reviewed-by: Nicholas Piggin <npig...@gmail.com> --- arch/powerpc/kvm/book3s_hv_nested.c | 32 +++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 8215dbd4be9a..d544b092b49a 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -99,7 +99,7 @@ static void byteswap_hv_regs(struct hv_guest_state *hr) hr->dawrx1 = swab64(hr->dawrx1); } -static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap, +static void save_hv_return_state(struct kvm_vcpu *vcpu, struct hv_guest_state *hr) { struct kvmppc_vcore *vc = vcpu->arch.vcore; @@ -118,7 +118,7 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap, hr->pidr = vcpu->arch.pid; hr->cfar = vcpu->arch.cfar; hr->ppr = vcpu->arch.ppr; - switch (trap) { + switch (vcpu->arch.trap) { case BOOK3S_INTERRUPT_H_DATA_STORAGE: hr->hdar = vcpu->arch.fault_dar; hr->hdsisr = vcpu->arch.fault_dsisr; @@ -128,9 +128,29 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap, hr->asdr = vcpu->arch.fault_gpa; break; case BOOK3S_INTERRUPT_H_FAC_UNAVAIL: - hr->hfscr = ((~HFSCR_INTR_CAUSE & hr->hfscr) | - (HFSCR_INTR_CAUSE & vcpu->arch.hfscr)); - break; + { + u8 cause = vcpu->arch.hfscr >> 56; + + WARN_ON_ONCE(cause >= BITS_PER_LONG); + + if (!(hr->hfscr & (1UL << cause))) { + hr->hfscr = ((~HFSCR_INTR_CAUSE & hr->hfscr) | + (HFSCR_INTR_CAUSE & vcpu->arch.hfscr)); + break; + } + + /* + * We have disabled this facility, so it does not + * exist from L1's perspective. Turn it into a HEAI. + */ + vcpu->arch.trap = BOOK3S_INTERRUPT_H_EMUL_ASSIST; + kvmppc_load_last_inst(vcpu, INST_GENERIC, &vcpu->arch.emul_inst); + + /* Don't leak the cause field */ + hr->hfscr &= ~HFSCR_INTR_CAUSE; + + fallthrough; + } case BOOK3S_INTERRUPT_H_EMUL_ASSIST: hr->heir = vcpu->arch.emul_inst; break; @@ -368,7 +388,7 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) delta_spurr = vcpu->arch.spurr - l2_hv.spurr; delta_ic = vcpu->arch.ic - l2_hv.ic; delta_vtb = vc->vtb - l2_hv.vtb; - save_hv_return_state(vcpu, vcpu->arch.trap, &l2_hv); + save_hv_return_state(vcpu, &l2_hv); /* restore L1 state */ vcpu->arch.nested = NULL; -- 2.29.2