Hi Marc, On 03/05/2017 12:45, Marc Zyngier wrote: > In order to be able to trap Group-1 GICv3 system registers, we need to > set ICH_HCR_EL2.TALL1 begore entering the guest. This is conditionnaly before, conditionally > done after having restored the guest's state, and cleared on exit. > > Signed-off-by: Marc Zyngier <[email protected]> > --- > include/linux/irqchip/arm-gic-v3.h | 1 + > virt/kvm/arm/hyp/vgic-v3-sr.c | 7 +++++++ > virt/kvm/arm/vgic/vgic-v3.c | 4 ++++ > 3 files changed, 12 insertions(+) > > diff --git a/include/linux/irqchip/arm-gic-v3.h > b/include/linux/irqchip/arm-gic-v3.h > index c56d9bc2c904..a1739843343e 100644 > --- a/include/linux/irqchip/arm-gic-v3.h > +++ b/include/linux/irqchip/arm-gic-v3.h > @@ -403,6 +403,7 @@ > > #define ICH_HCR_EN (1 << 0) > #define ICH_HCR_UIE (1 << 1) > +#define ICH_HCR_TALL1 (1 << 12) > #define ICH_HCR_EOIcount_SHIFT 27 > #define ICH_HCR_EOIcount_MASK (0x1f << ICH_HCR_EOIcount_SHIFT) > > diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c > index a521e105ade1..a27671b1e9af 100644 > --- a/virt/kvm/arm/hyp/vgic-v3-sr.c > +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c > @@ -257,6 +257,9 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu > *vcpu) > cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0); > } > } else { > + if (static_branch_unlikely(&vgic_v3_cpuif_trap)) > + write_gicreg(0, ICH_HCR_EL2); Not directly related to this patch but this is not obvious to me why we reset the ICH_HCR_EL2 only when used_lrs != 0. > + > cpu_if->vgic_elrsr = 0xffff; > cpu_if->vgic_ap0r[0] = 0; > cpu_if->vgic_ap0r[1] = 0; > @@ -329,6 +332,10 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu > *vcpu) > > for (i = 0; i < used_lrs; i++) > __gic_v3_set_lr(cpu_if->vgic_lr[i], i); > + } else { > + /* Always write ICH_HCR_EL2 to enable trapping */ "always" is a bit weird as this is conditional > + if (static_branch_unlikely(&vgic_v3_cpuif_trap)) > + write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2); and same question here. Why don't we always restore the ICH_HCR_EL2. Assuming when exiting the guest the vCPU I/F was enabled and used_lrs=0, when restoring don't we leave the vCPU I/F disabled? I must miss something but I don't find who is re-enabling the vCPU I/F in that case? > } > > /* > diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c > index 063526443781..547b8374fb64 100644 > --- a/virt/kvm/arm/vgic/vgic-v3.c > +++ b/virt/kvm/arm/vgic/vgic-v3.c > @@ -21,6 +21,8 @@ > > #include "vgic.h" > > +static bool group1_trap; > + > void vgic_v3_set_underflow(struct kvm_vcpu *vcpu) > { > struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3; > @@ -239,6 +241,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu) > > /* Get the show on the road... */ > vgic_v3->vgic_hcr = ICH_HCR_EN; > + if (group1_trap) I don't remember the rationale behind using the bool here and using static_branch_unlikely in the other cases.
May be good to squash the next patch to understand how group1_trap is set. Thanks Eric > + vgic_v3->vgic_hcr |= ICH_HCR_TALL1; > } > > /* check for overlapping regions and for regions crossing the end of memory > */ > _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
