Subject: [PATCH v2 29/94] KVM: arm64: nv: Forward debug traps to the nested guest

From: Marc Zyngier <[email-masked]>
Date: Tue, 11 Feb 2020 17:48:33 +0000

On handling a debug trap, check whether we need to forward it to the
guest before handling it.

Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/include/asm/kvm_nested.h | 2 ++
 arch/arm64/kvm/emulate-nested.c     | 9 +++++++--
 arch/arm64/kvm/sys_regs.c           | 3 +++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index c75e4326a363..5911a713c7dd 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -11,6 +11,8 @@ static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
 }
 
 int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe);
+extern bool __forward_traps(struct kvm_vcpu *vcpu, unsigned int reg,
+			    u64 control_bit);
 extern bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit);
 extern bool forward_nv_traps(struct kvm_vcpu *vcpu);
 
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 957a4a84d802..8380ed810062 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -24,14 +24,14 @@
 
 #include "trace.h"
 
-bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit)
+bool __forward_traps(struct kvm_vcpu *vcpu, unsigned int reg, u64 control_bit)
 {
 	bool control_bit_set;
 
 	if (!nested_virt_in_use(vcpu))
 		return false;
 
-	control_bit_set = __vcpu_sys_reg(vcpu, HCR_EL2) & control_bit;
+	control_bit_set = __vcpu_sys_reg(vcpu, reg) & control_bit;
 	if (!vcpu_mode_el2(vcpu) && control_bit_set) {
 		kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
 		return true;
@@ -39,6 +39,11 @@ bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit)
 	return false;
 }
 
+bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit)
+{
+	return __forward_traps(vcpu, HCR_EL2, control_bit);
+}
+
 bool forward_nv_traps(struct kvm_vcpu *vcpu)
 {
 	return forward_traps(vcpu, HCR_NV);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index dd4f8fe143ba..435340a49634 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -672,6 +672,9 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu,
 			    struct sys_reg_params *p,
 			    const struct sys_reg_desc *r)
 {
+	if (__forward_traps(vcpu, MDCR_EL2, MDCR_EL2_TDA | MDCR_EL2_TDE))
+		return false;
+
 	access_rw(vcpu, p, r);
 	if (p->is_write)
 		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
-- 
2.20.1

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