Hi Marc, On Mon, Nov 29, 2021 at 08:00:55PM +0000, Marc Zyngier wrote: > From: Jintack Lim <[email protected]> > > Support injecting exceptions and performing exception returns to and > from virtual EL2. This must be done entirely in software except when > taking an exception from vEL0 to vEL2 when the virtual HCR_EL2.{E2H,TGE} > == {1,1} (a VHE guest hypervisor). > > Signed-off-by: Jintack Lim <[email protected]> > Signed-off-by: Christoffer Dall <[email protected]> > [maz: switch to common exception injection framework] > Signed-off-by: Marc Zyngier <[email protected]> > --- > > [..] > > diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c > new file mode 100644 > index 000000000000..339e8272b01e > --- /dev/null > +++ b/arch/arm64/kvm/emulate-nested.c > @@ -0,0 +1,176 @@ > +/* > + * Copyright (C) 2016 - Linaro and Columbia University > + * Author: Jintack Lim <[email protected]> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program. If not, see <http://www.gnu.org/licenses/>. > + */ > + > +#include <linux/kvm.h> > +#include <linux/kvm_host.h> > + > +#include <asm/kvm_emulate.h> > +#include <asm/kvm_nested.h> > + > +#include "hyp/include/hyp/adjust_pc.h" > + > +#include "trace.h" > + > +void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) > +{ > + u64 spsr, elr, mode; > + bool direct_eret; > + > + /* > + * Going through the whole put/load motions is a waste of time > + * if this is a VHE guest hypervisor returning to its own > + * userspace, or the hypervisor performing a local exception > + * return. No need to save/restore registers, no need to > + * switch S2 MMU. Just do the canonical ERET. > + */ > + spsr = vcpu_read_sys_reg(vcpu, SPSR_EL2); > + mode = spsr & (PSR_MODE_MASK | PSR_MODE32_BIT); > + > + direct_eret = (mode == PSR_MODE_EL0t && > + vcpu_el2_e2h_is_set(vcpu) && > + vcpu_el2_tge_is_set(vcpu)); > + direct_eret |= (mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t); > + > + if (direct_eret) { > + *vcpu_pc(vcpu) = vcpu_read_sys_reg(vcpu, ELR_EL2); > + *vcpu_cpsr(vcpu) = spsr; > + trace_kvm_nested_eret(vcpu, *vcpu_pc(vcpu), spsr); > + return; > + } > + > + preempt_disable(); > + kvm_arch_vcpu_put(vcpu); > + > + elr = __vcpu_sys_reg(vcpu, ELR_EL2); > + > + trace_kvm_nested_eret(vcpu, elr, spsr); > + > + /* > + * Note that the current exception level is always the virtual EL2, > + * since we set HCR_EL2.NV bit only when entering the virtual EL2. > + */ > + *vcpu_pc(vcpu) = elr; > + *vcpu_cpsr(vcpu) = spsr; > + > + kvm_arch_vcpu_load(vcpu, smp_processor_id()); > + preempt_enable();
According to ARM DDI 0487G.a, page D13-3289, ERET'ing to EL1 when HCR_EL2.TGE is set is an illegal exception return. I don't see this case treated here. Thanks, Alex _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
