[PATCH v7 26/68] KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting

[Marc Zyngier]

From: Jintack Lim <jintack at cs.columbia.edu>

Forward ELR_EL1, SPSR_EL1 and VBAR_EL1 traps to the virtual EL2 if the
virtual HCR_EL2.{NV,NV1}={1,1}.

This is for recursive nested virtualization.

Signed-off-by: Jintack Lim <jintack at cs.columbia.edu>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/kvm_arm.h    |  1 +
 arch/arm64/include/asm/kvm_nested.h |  1 +
 arch/arm64/kvm/emulate-nested.c     |  5 +++++
 arch/arm64/kvm/sys_regs.c           | 21 ++++++++++++++++++++-
 4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 3f98c115d029..8425ef64d31a 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -20,6 +20,7 @@
 #define HCR_AMVOFFEN	(UL(1) << 51)
 #define HCR_FIEN	(UL(1) << 47)
 #define HCR_FWB		(UL(1) << 46)
+#define HCR_NV1		(UL(1) << 43)
 #define HCR_NV		(UL(1) << 42)
 #define HCR_API		(UL(1) << 41)
 #define HCR_APK		(UL(1) << 40)
diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index befd2501d5ba..7633a8c845c4 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -61,5 +61,6 @@ static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0)
 
 extern bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit);
 extern bool forward_nv_traps(struct kvm_vcpu *vcpu);
+extern bool forward_nv1_traps(struct kvm_vcpu *vcpu);
 
 #endif /* __ARM64_KVM_NESTED_H */
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 75cf6f15accc..7c06844a5113 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -34,6 +34,11 @@ bool forward_nv_traps(struct kvm_vcpu *vcpu)
 	return forward_traps(vcpu, HCR_NV);
 }
 
+bool forward_nv1_traps(struct kvm_vcpu *vcpu)
+{
+	return forward_traps(vcpu, HCR_NV1);
+}
+
 static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr)
 {
 	u64 mode = spsr & PSR_MODE_MASK;
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 988bd907f4f2..86b8d0c14d26 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -284,6 +284,16 @@ static bool access_rw(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static bool access_vbar_el1(struct kvm_vcpu *vcpu,
+			    struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	if (forward_nv1_traps(vcpu))
+		return false;
+
+	return access_rw(vcpu, p, r);
+}
+
 /*
  * See note at ARMv7 ARM B1.14.4 (TL;DR: S/W ops are not easily virtualized).
  */
@@ -1756,6 +1766,9 @@ static bool access_elr(struct kvm_vcpu *vcpu,
 	if (el12_reg(p) && forward_nv_traps(vcpu))
 		return false;
 
+	if (!el12_reg(p) && forward_nv1_traps(vcpu))
+		return false;
+
 	if (p->is_write)
 		vcpu_write_sys_reg(vcpu, p->regval, ELR_EL1);
 	else
@@ -1771,6 +1784,9 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
 	if (el12_reg(p) && forward_nv_traps(vcpu))
 		return false;
 
+	if (!el12_reg(p) && forward_nv1_traps(vcpu))
+		return false;
+
 	if (p->is_write)
 		__vcpu_sys_reg(vcpu, SPSR_EL1) = p->regval;
 	else
@@ -1786,6 +1802,9 @@ static bool access_spsr_el2(struct kvm_vcpu *vcpu,
 	if (el12_reg(p) && forward_nv_traps(vcpu))
 		return false;
 
+	if (!el12_reg(p) && forward_nv1_traps(vcpu))
+		return false;
+
 	if (p->is_write)
 		vcpu_write_sys_reg(vcpu, p->regval, SPSR_EL2);
 	else
@@ -2000,7 +2019,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_LORC_EL1), trap_loregion },
 	{ SYS_DESC(SYS_LORID_EL1), trap_loregion },
 
-	{ SYS_DESC(SYS_VBAR_EL1), access_rw, reset_val, VBAR_EL1, 0 },
+	{ SYS_DESC(SYS_VBAR_EL1), access_vbar_el1, reset_val, VBAR_EL1, 0 },
 	{ SYS_DESC(SYS_DISR_EL1), NULL, reset_val, DISR_EL1, 0 },
 
 	{ SYS_DESC(SYS_ICC_IAR0_EL1), write_to_read_only },
-- 
2.34.1