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>
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 5e9b4ef..d8a6931 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/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 @@
 		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