KVM: PPC: Use PACA backed shadow vcpu

We're being horribly racy right now. All the entry and exit code hijacks
random fields from the PACA that could easily be used by different code in
case we get interrupted, for example by a #MC or even page fault.

After discussing this with Ben, we figured it's best to reserve some more
space in the PACA and just shove off some vcpu state to there.

That way we can drastically improve the readability of the code, make it
less racy and less complex.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/include/asm/kvm_book3s.h

@@ -23,6 +23,7 @@
 #include <linux/types.h>
 #include <linux/kvm_host.h>
 #include <asm/kvm_ppc.h>
+#include <asm/kvm_book3s_64_asm.h>
 
 struct kvmppc_slb {
 	u64 esid;
@@ -69,6 +70,7 @@ struct kvmppc_sid_map {
 
 struct kvmppc_vcpu_book3s {
 	struct kvm_vcpu vcpu;
+	struct kvmppc_book3s_shadow_vcpu shadow_vcpu;
 	struct kvmppc_sid_map sid_map[SID_MAP_NUM];
 	struct kvmppc_slb slb[64];
 	struct {

arch/powerpc/include/asm/kvm_book3s_64_asm.h

@@ -20,6 +20,8 @@
 #ifndef __ASM_KVM_BOOK3S_ASM_H__
 #define __ASM_KVM_BOOK3S_ASM_H__
 
+#ifdef __ASSEMBLY__
+
 #ifdef CONFIG_KVM_BOOK3S_64_HANDLER
 
 #include <asm/kvm_asm.h>
@@ -55,4 +57,21 @@ kvmppc_resume_\intno:
 
 #endif /* CONFIG_KVM_BOOK3S_64_HANDLER */
 
+#else  /*__ASSEMBLY__ */
+
+struct kvmppc_book3s_shadow_vcpu {
+	ulong gpr[14];
+	u32 cr;
+	u32 xer;
+	ulong host_r1;
+	ulong host_r2;
+	ulong handler;
+	ulong scratch0;
+	ulong scratch1;
+	ulong vmhandler;
+	ulong rmhandler;
+};
+
+#endif /*__ASSEMBLY__ */
+
 #endif /* __ASM_KVM_BOOK3S_ASM_H__ */

arch/powerpc/include/asm/kvm_host.h

@@ -175,10 +175,13 @@ struct kvm_vcpu_arch {
 	ulong gpr[32];
 
 	ulong pc;
-	u32 cr;
 	ulong ctr;
 	ulong lr;
+
+#ifdef CONFIG_BOOKE
 	ulong xer;
+	u32 cr;
+#endif
 
 	ulong msr;
 #ifdef CONFIG_PPC64

arch/powerpc/include/asm/kvm_ppc.h

@@ -98,34 +98,42 @@ extern void kvmppc_core_destroy_mmu(struct kvm_vcpu *vcpu);
 
 #ifdef CONFIG_PPC_BOOK3S
 
+/* We assume we're always acting on the current vcpu */
+
 static inline void kvmppc_set_gpr(struct kvm_vcpu *vcpu, int num, ulong val)
 {
-	vcpu->arch.gpr[num] = val;
+	if ( num < 14 )
+		get_paca()->shadow_vcpu.gpr[num] = val;
+	else
+		vcpu->arch.gpr[num] = val;
 }
 
 static inline ulong kvmppc_get_gpr(struct kvm_vcpu *vcpu, int num)
 {
-	return vcpu->arch.gpr[num];
+	if ( num < 14 )
+		return get_paca()->shadow_vcpu.gpr[num];
+	else
+		return vcpu->arch.gpr[num];
 }
 
 static inline void kvmppc_set_cr(struct kvm_vcpu *vcpu, u32 val)
 {
-	vcpu->arch.cr = val;
+	get_paca()->shadow_vcpu.cr = val;
 }
 
 static inline u32 kvmppc_get_cr(struct kvm_vcpu *vcpu)
 {
-	return vcpu->arch.cr;
+	return get_paca()->shadow_vcpu.cr;
 }
 
 static inline void kvmppc_set_xer(struct kvm_vcpu *vcpu, u32 val)
 {
-	vcpu->arch.xer = val;
+	get_paca()->shadow_vcpu.xer = val;
 }
 
 static inline u32 kvmppc_get_xer(struct kvm_vcpu *vcpu)
 {
-	return vcpu->arch.xer;
+	return get_paca()->shadow_vcpu.xer;
 }
 
 #else

arch/powerpc/include/asm/paca.h

@@ -19,6 +19,9 @@
 #include <asm/mmu.h>
 #include <asm/page.h>
 #include <asm/exception-64e.h>
+#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
+#include <asm/kvm_book3s_64_asm.h>
+#endif
 
 register struct paca_struct *local_paca asm("r13");
 
@@ -135,6 +138,8 @@ struct paca_struct {
 		u64     esid;
 		u64     vsid;
 	} kvm_slb[64];			/* guest SLB */
+	/* We use this to store guest state in */
+	struct kvmppc_book3s_shadow_vcpu shadow_vcpu;
 	u8 kvm_slb_max;			/* highest used guest slb entry */
 	u8 kvm_in_guest;		/* are we inside the guest? */
 #endif