Next on our list of useless accesses is the maintenance interrupt status registers (ICH_MISR_EL2, ICH_EISR_EL2).
It is pointless to save them if we haven't asked for a maintenance interrupt the first place, which can only happen for two reasons: - Underflow: ICH_HCR_UIE will be set, - EOI: ICH_LR_EOI will be set. These conditions can be checked on the in-memory copies of the regs. Should any of these two condition be valid, we must read GICH_MISR. We can then check for ICH_MISR_EOI, and only when set read ICH_EISR_EL2. This means that in most case, we don't have to save them at all. Reviewed-by: Christoffer Dall <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> --- arch/arm64/kvm/hyp/vgic-v3-sr.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c index e596945..61a5e46 100644 --- a/arch/arm64/kvm/hyp/vgic-v3-sr.c +++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c @@ -131,6 +131,35 @@ static void __hyp_text __gic_v3_set_lr(u64 val, int lr) } } +static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu, int nr_lr) +{ + struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3; + int i; + bool expect_mi; + + expect_mi = !!(cpu_if->vgic_hcr & ICH_HCR_UIE); + + for (i = 0; i < nr_lr; i++) { + if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i))) + continue; + + expect_mi |= (!(cpu_if->vgic_lr[i] & ICH_LR_HW) && + (cpu_if->vgic_lr[i] & ICH_LR_EOI)); + } + + if (expect_mi) { + cpu_if->vgic_misr = read_gicreg(ICH_MISR_EL2); + + if (cpu_if->vgic_misr & ICH_MISR_EOI) + cpu_if->vgic_eisr = read_gicreg(ICH_EISR_EL2); + else + cpu_if->vgic_eisr = 0; + } else { + cpu_if->vgic_misr = 0; + cpu_if->vgic_eisr = 0; + } +} + void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu) { struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3; @@ -148,8 +177,6 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu) int i; u32 max_lr_idx, nr_pri_bits; - cpu_if->vgic_misr = read_gicreg(ICH_MISR_EL2); - cpu_if->vgic_eisr = read_gicreg(ICH_EISR_EL2); cpu_if->vgic_elrsr = read_gicreg(ICH_ELSR_EL2); write_gicreg(0, ICH_HCR_EL2); @@ -157,6 +184,8 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu) max_lr_idx = vtr_to_max_lr_idx(val); nr_pri_bits = vtr_to_nr_pri_bits(val); + save_maint_int_state(vcpu, max_lr_idx + 1); + for (i = 0; i <= max_lr_idx; i++) { if (vcpu->arch.vgic_cpu.live_lrs & (1UL << i)) cpu_if->vgic_lr[i] = __gic_v3_get_lr(i); -- 2.1.4 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
