KVM: arm/arm64: Move VGIC APR save/restore to vgic put/load

The APRs can only have bits set when the guest acknowledges an interrupt
in the LR and can only have a bit cleared when the guest EOIs an
interrupt in the LR.  Therefore, if we have no LRs with any
pending/active interrupts, the APR cannot change value and there is no
need to clear it on every exit from the VM (hint: it will have already
been cleared when we exited the guest the last time with the LRs all
EOIed).

The only case we need to take care of is when we migrate the VCPU away
from a CPU or migrate a new VCPU onto a CPU, or when we return to
userspace to capture the state of the VCPU for migration.  To make sure
this works, factor out the APR save/restore functionality into separate
functions called from the VCPU (and by extension VGIC) put/load hooks.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/kvm_hyp.h

@@ -110,6 +110,8 @@ void __sysreg_restore_state(struct kvm_cpu_context *ctxt);
 
 void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
 void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
+void __vgic_v3_save_aprs(struct kvm_vcpu *vcpu);
+void __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu);
 
 asmlinkage void __vfp_save_state(struct vfp_hard_struct *vfp);
 asmlinkage void __vfp_restore_state(struct vfp_hard_struct *vfp);

arch/arm64/include/asm/kvm_hyp.h

@@ -124,6 +124,8 @@ int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu);
 
 void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
 void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
+void __vgic_v3_save_aprs(struct kvm_vcpu *vcpu);
+void __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu);
 int __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu);
 
 void __timer_enable_traps(struct kvm_vcpu *vcpu);

virt/kvm/arm/hyp/vgic-v3-sr.c

@@ -21,6 +21,7 @@
 
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
 
 #define vtr_to_max_lr_idx(v)		((v) & 0xf)
 #define vtr_to_nr_pre_bits(v)		((((u32)(v) >> 26) & 7) + 1)
@@ -221,14 +222,11 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 
 	if (used_lrs) {
 		int i;
-		u32 nr_pre_bits;
 		u32 elrsr;
 
 		elrsr = read_gicreg(ICH_ELSR_EL2);
 
 		write_gicreg(0, ICH_HCR_EL2);
-		val = read_gicreg(ICH_VTR_EL2);
-		nr_pre_bits = vtr_to_nr_pre_bits(val);
 
 		for (i = 0; i < used_lrs; i++) {
 			if (elrsr & (1 << i))
@@ -238,39 +236,10 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 
 			__gic_v3_set_lr(0, i);
 		}
-
-		switch (nr_pre_bits) {
-		case 7:
-			cpu_if->vgic_ap0r[3] = __vgic_v3_read_ap0rn(3);
-			cpu_if->vgic_ap0r[2] = __vgic_v3_read_ap0rn(2);
-		case 6:
-			cpu_if->vgic_ap0r[1] = __vgic_v3_read_ap0rn(1);
-		default:
-			cpu_if->vgic_ap0r[0] = __vgic_v3_read_ap0rn(0);
-		}
-
-		switch (nr_pre_bits) {
-		case 7:
-			cpu_if->vgic_ap1r[3] = __vgic_v3_read_ap1rn(3);
-			cpu_if->vgic_ap1r[2] = __vgic_v3_read_ap1rn(2);
-		case 6:
-			cpu_if->vgic_ap1r[1] = __vgic_v3_read_ap1rn(1);
-		default:
-			cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
-		}
 	} else {
 		if (static_branch_unlikely(&vgic_v3_cpuif_trap) ||
 		    cpu_if->its_vpe.its_vm)
 			write_gicreg(0, ICH_HCR_EL2);
-
-		cpu_if->vgic_ap0r[0] = 0;
-		cpu_if->vgic_ap0r[1] = 0;
-		cpu_if->vgic_ap0r[2] = 0;
-		cpu_if->vgic_ap0r[3] = 0;
-		cpu_if->vgic_ap1r[0] = 0;
-		cpu_if->vgic_ap1r[1] = 0;
-		cpu_if->vgic_ap1r[2] = 0;
-		cpu_if->vgic_ap1r[3] = 0;
 	}
 
 	val = read_gicreg(ICC_SRE_EL2);
@@ -287,8 +256,6 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
 	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
-	u64 val;
-	u32 nr_pre_bits;
 	int i;
 
 	/*
@@ -306,32 +273,9 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 		write_gicreg(cpu_if->vgic_vmcr, ICH_VMCR_EL2);
 	}
 
-	val = read_gicreg(ICH_VTR_EL2);
-	nr_pre_bits = vtr_to_nr_pre_bits(val);
-
 	if (used_lrs) {
 		write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
 
-		switch (nr_pre_bits) {
-		case 7:
-			__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[3], 3);
-			__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[2], 2);
-		case 6:
-			__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[1], 1);
-		default:
-			__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[0], 0);
-		}
-
-		switch (nr_pre_bits) {
-		case 7:
-			__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[3], 3);
-			__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[2], 2);
-		case 6:
-			__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[1], 1);
-		default:
-			__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[0], 0);
-		}
-
 		for (i = 0; i < used_lrs; i++)
 			__gic_v3_set_lr(cpu_if->vgic_lr[i], i);
 	} else {
@@ -364,6 +308,72 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 		     ICC_SRE_EL2);
 }
 
+void __hyp_text __vgic_v3_save_aprs(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v3_cpu_if *cpu_if;
+	u64 val;
+	u32 nr_pre_bits;
+
+	vcpu = kern_hyp_va(vcpu);
+	cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+
+	val = read_gicreg(ICH_VTR_EL2);
+	nr_pre_bits = vtr_to_nr_pre_bits(val);
+
+	switch (nr_pre_bits) {
+	case 7:
+		cpu_if->vgic_ap0r[3] = __vgic_v3_read_ap0rn(3);
+		cpu_if->vgic_ap0r[2] = __vgic_v3_read_ap0rn(2);
+	case 6:
+		cpu_if->vgic_ap0r[1] = __vgic_v3_read_ap0rn(1);
+	default:
+		cpu_if->vgic_ap0r[0] = __vgic_v3_read_ap0rn(0);
+	}
+
+	switch (nr_pre_bits) {
+	case 7:
+		cpu_if->vgic_ap1r[3] = __vgic_v3_read_ap1rn(3);
+		cpu_if->vgic_ap1r[2] = __vgic_v3_read_ap1rn(2);
+	case 6:
+		cpu_if->vgic_ap1r[1] = __vgic_v3_read_ap1rn(1);
+	default:
+		cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
+	}
+}
+
+void __hyp_text __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v3_cpu_if *cpu_if;
+	u64 val;
+	u32 nr_pre_bits;
+
+	vcpu = kern_hyp_va(vcpu);
+	cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+
+	val = read_gicreg(ICH_VTR_EL2);
+	nr_pre_bits = vtr_to_nr_pre_bits(val);
+
+	switch (nr_pre_bits) {
+	case 7:
+		__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[3], 3);
+		__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[2], 2);
+	case 6:
+		__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[1], 1);
+	default:
+		__vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[0], 0);
+	}
+
+	switch (nr_pre_bits) {
+	case 7:
+		__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[3], 3);
+		__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[2], 2);
+	case 6:
+		__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[1], 1);
+	default:
+		__vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[0], 0);
+	}
+}
+
 void __hyp_text __vgic_v3_init_lrs(void)
 {
 	int max_lr_idx = vtr_to_max_lr_idx(read_gicreg(ICH_VTR_EL2));

virt/kvm/arm/vgic/vgic-v2.c

@@ -446,7 +446,6 @@ void vgic_v2_save_state(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
 	struct vgic_dist *vgic = &kvm->arch.vgic;
-	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
 	void __iomem *base = vgic->vctrl_base;
 	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 
@@ -454,11 +453,8 @@ void vgic_v2_save_state(struct kvm_vcpu *vcpu)
 		return;
 
 	if (used_lrs) {
-		cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
 		save_lrs(vcpu, base);
 		writel_relaxed(0, base + GICH_HCR);
-	} else {
-		cpu_if->vgic_apr = 0;
 	}
 }
 
@@ -476,7 +472,6 @@ void vgic_v2_restore_state(struct kvm_vcpu *vcpu)
 
 	if (used_lrs) {
 		writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
-		writel_relaxed(cpu_if->vgic_apr, base + GICH_APR);
 		for (i = 0; i < used_lrs; i++) {
 			writel_relaxed(cpu_if->vgic_lr[i],
 				       base + GICH_LR0 + (i * 4));
@@ -490,6 +485,7 @@ void vgic_v2_load(struct kvm_vcpu *vcpu)
 	struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
 
 	writel_relaxed(cpu_if->vgic_vmcr, vgic->vctrl_base + GICH_VMCR);
+	writel_relaxed(cpu_if->vgic_apr, vgic->vctrl_base + GICH_APR);
 }
 
 void vgic_v2_put(struct kvm_vcpu *vcpu)
@@ -498,4 +494,5 @@ void vgic_v2_put(struct kvm_vcpu *vcpu)
 	struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
 
 	cpu_if->vgic_vmcr = readl_relaxed(vgic->vctrl_base + GICH_VMCR);
+	cpu_if->vgic_apr = readl_relaxed(vgic->vctrl_base + GICH_APR);
 }

virt/kvm/arm/vgic/vgic-v3.c

@@ -16,6 +16,7 @@
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 #include <kvm/arm_vgic.h>
+#include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_asm.h>
 
@@ -587,6 +588,8 @@ void vgic_v3_load(struct kvm_vcpu *vcpu)
 	 */
 	if (likely(cpu_if->vgic_sre))
 		kvm_call_hyp(__vgic_v3_write_vmcr, cpu_if->vgic_vmcr);
+
+	kvm_call_hyp(__vgic_v3_restore_aprs, vcpu);
 }
 
 void vgic_v3_put(struct kvm_vcpu *vcpu)
@@ -595,4 +598,6 @@ void vgic_v3_put(struct kvm_vcpu *vcpu)
 
 	if (likely(cpu_if->vgic_sre))
 		cpu_if->vgic_vmcr = kvm_call_hyp(__vgic_v3_read_vmcr);
+
+	kvm_call_hyp(__vgic_v3_save_aprs, vcpu);
 }