[PATCH v3 38/66] KVM: arm64: nv: Introduce sys_reg_desc.forward_trap

[Marc Zyngier]

From: Jintack Lim <jintack.lim at linaro.org>

This introduces a function prototype to determine if we need to forward
system instruction traps to the virtual EL2. The implementation of
forward_trap functions for each system instruction will be added in
later patches.

Signed-off-by: Jintack Lim <jintack.lim at linaro.org>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/sys_regs.c | 8 ++++++++
 arch/arm64/kvm/sys_regs.h | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 090ce14306ba..8f1378dfec6c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2490,6 +2490,14 @@ static void perform_access(struct kvm_vcpu *vcpu,
 	 */
 	BUG_ON(!r->access);
 
+	/*
+	 * Forward this trap to the virtual EL2 if the guest hypervisor has
+	 * configured to trap the current instruction.
+	 */
+	if (nested_virt_in_use(vcpu) && r->forward_trap
+	    && unlikely(r->forward_trap(vcpu)))
+		return;
+
 	/* Skip instruction if instructed so */
 	if (likely(r->access(vcpu, params, r)))
 		kvm_incr_pc(vcpu);
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 9d0621417c2a..62ca4119069a 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -58,6 +58,12 @@ struct sys_reg_desc {
 	int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 			const struct kvm_one_reg *reg, void __user *uaddr);
 
+	/*
+	 * Forward the trap to the virtual EL2 if the guest hypervisor has
+	 * configured to trap the current instruction.
+	 */
+	bool (*forward_trap)(struct kvm_vcpu *vcpu);
+
 	/* Return mask of REG_* runtime visibility overrides */
 	unsigned int (*visibility)(const struct kvm_vcpu *vcpu,
 				   const struct sys_reg_desc *rd);
-- 
2.29.2