Hi Marc, On Tue, Aug 15, 2023 at 11:47 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > Although the nVHE behaviour requires HCRX_EL2 to be switched > on each switch between host and guest, there is nothing in > this register that would affect a VHE host. > > It is thus possible to save/restore this register on load/put > on VHE systems, avoiding unnecessary sysreg access on the hot > path. Additionally, it avoids unnecessary traps when running > with NV. > > To achieve this, simply move the read/writes to the *_common() > helpers, which are called on load/put on VHE, and more eagerly > on nVHE. > > Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > --- > arch/arm64/kvm/hyp/include/hyp/switch.h | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h > index a4750070563f..060c5a0409e5 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/switch.h > +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h > @@ -197,6 +197,9 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu) > vcpu->arch.mdcr_el2_host = read_sysreg(mdcr_el2); > write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); > > + if (cpus_have_final_cap(ARM64_HAS_HCX)) > + write_sysreg_s(HCRX_GUEST_FLAGS, SYS_HCRX_EL2); > + > __activate_traps_hfgxtr(vcpu); > } > > @@ -213,6 +216,9 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu) > vcpu_clear_flag(vcpu, PMUSERENR_ON_CPU); > } > > + if (cpus_have_final_cap(ARM64_HAS_HCX)) > + write_sysreg_s(HCRX_HOST_FLAGS, SYS_HCRX_EL2); > + > __deactivate_traps_hfgxtr(vcpu); > } > > @@ -227,9 +233,6 @@ static inline void ___activate_traps(struct kvm_vcpu *vcpu) > > if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN) && (hcr & HCR_VSE)) > write_sysreg_s(vcpu->arch.vsesr_el2, SYS_VSESR_EL2); > - > - if (cpus_have_final_cap(ARM64_HAS_HCX)) > - write_sysreg_s(HCRX_GUEST_FLAGS, SYS_HCRX_EL2); > } > > static inline void ___deactivate_traps(struct kvm_vcpu *vcpu) > @@ -244,9 +247,6 @@ static inline void ___deactivate_traps(struct kvm_vcpu *vcpu) > vcpu->arch.hcr_el2 &= ~HCR_VSE; > vcpu->arch.hcr_el2 |= read_sysreg(hcr_el2) & HCR_VSE; > } > - > - if (cpus_have_final_cap(ARM64_HAS_HCX)) > - write_sysreg_s(HCRX_HOST_FLAGS, SYS_HCRX_EL2); > } > > static inline bool __populate_fault_info(struct kvm_vcpu *vcpu) > -- > 2.34.1 > Reviewed-by: Jing Zhang <jingzhangos@xxxxxxxxxx> Jing
