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From: Oliver Upton To: Marc Zyngier Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Alexandru Elisei , Mark Brown Subject: Re: [PATCH v4 07/36] KVM: arm64: nv: Save/Restore vEL2 sysregs Message-ID: References: <20241009190019.3222687-1-maz@kernel.org> <20241009190019.3222687-8-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241009190019.3222687-8-maz@kernel.org> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241009_125535_243055_87566032 X-CRM114-Status: GOOD ( 17.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 09, 2024 at 07:59:50PM +0100, Marc Zyngier wrote: > +static void __sysreg_restore_vel2_state(struct kvm_vcpu *vcpu) > +{ > + u64 val; > + > + /* These registers are common with EL1 */ > + write_sysreg(__vcpu_sys_reg(vcpu, PAR_EL1), par_el1); > + write_sysreg(__vcpu_sys_reg(vcpu, TPIDR_EL1), tpidr_el1); > + > + write_sysreg(read_cpuid_id(), vpidr_el2); I don't think we need to restore VPIDR_EL2 here, so long as we do it on vcpu_put() when leaving a nested VM context. That seems like the right place to have it, as we could be running a mix of nested and non-nested VMs and don't ever poke VPIDR_EL2 for non-NV VMs. > @@ -89,7 +192,29 @@ void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu) > */ > __sysreg32_restore_state(vcpu); > __sysreg_restore_user_state(guest_ctxt); > - __sysreg_restore_el1_state(guest_ctxt); > + > + if (unlikely(__is_hyp_ctxt(guest_ctxt))) { > + __sysreg_restore_vel2_state(vcpu); > + } else { > + if (vcpu_has_nv(vcpu)) { > + /* > + * Only set VPIDR_EL2 for nested VMs, as this is the > + * only time it changes. We'll restore the MIDR_EL1 > + * view on put. > + */ Slightly ambiguous what "VPIDR_EL2" this is referring to (hardware reg v. guest value). Maybe: /* * Use the guest hypervisor's VPIDR_EL2 when in a nested * state. The hardware value of MIDR_EL1 gets restored on * put. */ > + write_sysreg(ctxt_sys_reg(guest_ctxt, VPIDR_EL2), vpidr_el2); > + > + /* > + * As we're restoring a nested guest, set the value > + * provided by the guest hypervisor. > + */ > + mpidr = ctxt_sys_reg(guest_ctxt, VMPIDR_EL2); > + } else { > + mpidr = ctxt_sys_reg(guest_ctxt, MPIDR_EL1); > + } > + > + __sysreg_restore_el1_state(guest_ctxt, mpidr); > + } > > vcpu_set_flag(vcpu, SYSREGS_ON_CPU); > } > @@ -112,12 +237,20 @@ void __vcpu_put_switch_sysregs(struct kvm_vcpu *vcpu) > > host_ctxt = host_data_ptr(host_ctxt); > > - __sysreg_save_el1_state(guest_ctxt); > + if (unlikely(__is_hyp_ctxt(guest_ctxt))) > + __sysreg_save_vel2_state(vcpu); > + else > + __sysreg_save_el1_state(guest_ctxt); > + > __sysreg_save_user_state(guest_ctxt); > __sysreg32_save_state(vcpu); > > /* Restore host user state */ > __sysreg_restore_user_state(host_ctxt); > > + /* If leaving a nesting guest, restore MPIDR_EL1 default view */ typo: MIDR_EL1 > + if (vcpu_has_nv(vcpu)) > + write_sysreg(read_cpuid_id(), vpidr_el2); > + > vcpu_clear_flag(vcpu, SYSREGS_ON_CPU); > } > -- > 2.39.2 > -- Thanks, Oliver