KVM: PPC: BookE: Add EPR ONE_REG sync

We need to be able to read and write the contents of the EPR register
from user space.

This patch implements that logic through the ONE_REG API and declares
its (never implemented) SREGS counterpart as deprecated.
Signed-off-by: Alexander Graf <agraf@suse.de>

Documentation/virtual/kvm/api.txt

@@ -1774,6 +1774,7 @@ registers, find a list below:
   PPC   | KVM_REG_PPC_VPA_SLB   | 128
   PPC   | KVM_REG_PPC_VPA_DTL   | 128
   PPC   | KVM_REG_PPC_EPCR	| 32
+  PPC   | KVM_REG_PPC_EPR	| 32
 
 4.69 KVM_GET_ONE_REG
 

arch/powerpc/include/uapi/asm/kvm.h

@@ -114,7 +114,10 @@ struct kvm_regs {
 /* Embedded Floating Point (SPE) -- IVOR32-34 if KVM_SREGS_E_IVOR */
 #define KVM_SREGS_E_SPE			(1 << 9)
 
-/* External Proxy (EXP) -- EPR */
+/*
+ * DEPRECATED! USE ONE_REG FOR THIS ONE!
+ * External Proxy (EXP) -- EPR
+ */
 #define KVM_SREGS_EXP			(1 << 10)
 
 /* External PID (E.PD) -- EPSC/EPLC */
@@ -412,5 +415,6 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_VPA_DTL	(KVM_REG_PPC | KVM_REG_SIZE_U128 | 0x84)
 
 #define KVM_REG_PPC_EPCR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x85)
+#define KVM_REG_PPC_EPR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x86)
 
 #endif /* __LINUX_KVM_POWERPC_H */

arch/powerpc/kvm/booke.c

@@ -300,6 +300,15 @@ static void set_guest_esr(struct kvm_vcpu *vcpu, u32 esr)
 #endif
 }
 
+static unsigned long get_guest_epr(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_KVM_BOOKE_HV
+	return mfspr(SPRN_GEPR);
+#else
+	return vcpu->arch.epr;
+#endif
+}
+
 /* Deliver the interrupt of the corresponding priority, if possible. */
 static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
                                         unsigned int priority)
@@ -1405,6 +1414,11 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 				 &vcpu->arch.dbg_reg.dac[dac], sizeof(u64));
 		break;
 	}
+	case KVM_REG_PPC_EPR: {
+		u32 epr = get_guest_epr(vcpu);
+		r = put_user(epr, (u32 __user *)(long)reg->addr);
+		break;
+	}
 #if defined(CONFIG_64BIT)
 	case KVM_REG_PPC_EPCR:
 		r = put_user(vcpu->arch.epcr, (u32 __user *)(long)reg->addr);
@@ -1437,6 +1451,13 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 			     (u64 __user *)(long)reg->addr, sizeof(u64));
 		break;
 	}
+	case KVM_REG_PPC_EPR: {
+		u32 new_epr;
+		r = get_user(new_epr, (u32 __user *)(long)reg->addr);
+		if (!r)
+			kvmppc_set_epr(vcpu, new_epr);
+		break;
+	}
 #if defined(CONFIG_64BIT)
 	case KVM_REG_PPC_EPCR: {
 		u32 new_epcr;