[PATCH v4 64/66] KVM: arm64: nv: Enable ARMv8.4-NV support

[Marc Zyngier]

As all the VNCR-capable system registers are nicely separated
from the rest of the crowd, let's set HCR_EL2.NV2 on and let
the ball rolling.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/kvm_arm.h     |  1 +
 arch/arm64/include/asm/kvm_emulate.h | 23 +++++++++++++----------
 arch/arm64/include/asm/sysreg.h      |  1 +
 arch/arm64/kvm/hyp/vhe/switch.c      | 14 +++++++++++++-
 4 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 6a4a11fcc9df..ce682bcce56f 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -14,6 +14,7 @@
 /* Hyp Configuration Register (HCR) bits */
 #define HCR_ATA		(UL(1) << 56)
 #define HCR_FWB		(UL(1) << 46)
+#define HCR_NV2		(UL(1) << 45)
 #define HCR_AT		(UL(1) << 44)
 #define HCR_NV1		(UL(1) << 43)
 #define HCR_NV		(UL(1) << 42)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 50e31006dc07..2f57c5aa2ac5 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -242,21 +242,24 @@ static inline bool is_hyp_ctxt(const struct kvm_vcpu *vcpu)
 
 static inline u64 __fixup_spsr_el2_write(struct kvm_cpu_context *ctxt, u64 val)
 {
-	if (!__vcpu_el2_e2h_is_set(ctxt)) {
-		/*
-		 * Clear the .M field when writing SPSR to the CPU, so that we
-		 * can detect when the CPU clobbered our SPSR copy during a
-		 * local exception.
-		 */
-		val &= ~0xc;
-	}
+	struct kvm_vcpu *vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt);
+
+	if (enhanced_nested_virt_in_use(vcpu) || __vcpu_el2_e2h_is_set(ctxt))
+		return val;
 
-	return val;
+	/*
+	 * Clear the .M field when writing SPSR to the CPU, so that we
+	 * can detect when the CPU clobbered our SPSR copy during a
+	 * local exception.
+	 */
+	return val &= ~0xc;
 }
 
 static inline u64 __fixup_spsr_el2_read(const struct kvm_cpu_context *ctxt, u64 val)
 {
-	if (__vcpu_el2_e2h_is_set(ctxt))
+	struct kvm_vcpu *vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt);
+
+	if (enhanced_nested_virt_in_use(vcpu) || __vcpu_el2_e2h_is_set(ctxt))
 		return val;
 
 	/*
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 286b09dbfc61..ff12d4c8b2d8 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -544,6 +544,7 @@
 #define SYS_TCR_EL2			sys_reg(3, 4, 2, 0, 2)
 #define SYS_VTTBR_EL2			sys_reg(3, 4, 2, 1, 0)
 #define SYS_VTCR_EL2			sys_reg(3, 4, 2, 1, 2)
+#define SYS_VNCR_EL2			sys_reg(3, 4, 2, 2, 0)
 
 #define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
 #define SYS_TRFCR_EL2			sys_reg(3, 4, 1, 2, 1)
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index b665a3cc288e..bd4ae1296de4 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -46,7 +46,13 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 			 * the EL1 virtual memory control register accesses
 			 * as well as the AT S1 operations.
 			 */
-			hcr |= HCR_TVM | HCR_TRVM | HCR_AT | HCR_TTLB | HCR_NV1;
+			if (enhanced_nested_virt_in_use(vcpu)) {
+				hcr &= ~HCR_TVM;
+			} else {
+				hcr |= HCR_TVM | HCR_TRVM | HCR_TTLB;
+			}
+
+			hcr |= HCR_AT | HCR_NV1;
 		} else {
 			/*
 			 * For a guest hypervisor on v8.1 (VHE), allow to
@@ -78,6 +84,12 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 			if (!vcpu_el2_tge_is_set(vcpu))
 				hcr |= HCR_AT | HCR_TTLB;
 		}
+
+		if (enhanced_nested_virt_in_use(vcpu)) {
+			hcr |= HCR_AT | HCR_TTLB | HCR_NV2;
+			write_sysreg_s(vcpu->arch.ctxt.vncr_array,
+				       SYS_VNCR_EL2);
+		}
 	} else if (nested_virt_in_use(vcpu)) {
 		hcr |= __vcpu_sys_reg(vcpu, HCR_EL2);
 	}
-- 
2.29.2