[PATCH 07/37] KVM: arm/arm64: Add kvm_vcpu_load_sysregs and kvm_vcpu_put_sysregs

[Christoffer Dall]

As we are about to move a buch of save/restore logic for VHE kernels to
the load and put functions, we need some infrastructure to do this.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
 arch/arm/include/asm/kvm_host.h   |  3 +++
 arch/arm64/include/asm/kvm_host.h |  3 +++
 arch/arm64/kvm/hyp/sysreg-sr.c    | 27 +++++++++++++++++++++++++++
 virt/kvm/arm/arm.c                |  2 ++
 4 files changed, 35 insertions(+)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 1100170..13f8165 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -290,4 +290,7 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
 int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
 			       struct kvm_device_attr *attr);
 
+static inline void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu) {}
+static inline void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu) {}
+
 #endif /* __ARM_KVM_HOST_H__ */
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27305e7..7d3bfa7 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -383,4 +383,7 @@ static inline void __cpu_init_stage2(void)
 		  "PARange is %d bits, unsupported configuration!", parange);
 }
 
+void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu);
+void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu);
+
 #endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
index c54cc2a..b7438c8 100644
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -183,3 +183,30 @@ void __hyp_text __sysreg32_restore_state(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY)
 		write_sysreg(sysreg[DBGVCR32_EL2], dbgvcr32_el2);
 }
+
+/**
+ * kvm_vcpu_load_sysregs - Load guest system register to physical CPU
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * If the kernel runs in EL2 then load the system register state for the VCPU
+ * for EL1 onto the physical CPU so that we can go back and foward between the
+ * VM and the hypervisor without switching all this state around.
+ */
+void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu)
+{
+}
+
+/**
+ * kvm_vcpu_put_sysregs - Restore host system register state to physical CPU
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * If the kernel runs in EL2 and the physical register state belongs to the
+ * VCPU, then restore the system register state for the host for EL1 onto the
+ * physical CPU so that we can run userspace and other threads on this
+ * physical CPU.
+ */
+void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
+{
+}
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index d495453..cf121b2 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -358,6 +358,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	kvm_arm_set_running_vcpu(vcpu);
 	kvm_vgic_load(vcpu);
 	kvm_timer_vcpu_load(vcpu);
+	kvm_vcpu_load_sysregs(vcpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
@@ -365,6 +366,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	if (vcpu->ioctl != KVM_RUN)
 		return;
 
+	kvm_vcpu_put_sysregs(vcpu);
 	kvm_timer_vcpu_put(vcpu);
 	kvm_vgic_put(vcpu);
 
-- 
2.9.0