KVM: PPC: Make shared struct aka magic page guest endian

The shared (magic) page is a data structure that contains often used
supervisor privileged SPRs accessible via memory to the user to reduce
the number of exits we have to take to read/write them.

When we actually share this structure with the guest we have to maintain
it in guest endianness, because some of the patch tricks only work with
native endian load/store operations.

Since we only share the structure with either host or guest in little
endian on book3s_64 pr mode, we don't have to worry about booke or book3s hv.

For booke, the shared struct stays big endian. For book3s_64 hv we maintain
the struct in host native endian, since it never gets shared with the guest.

For book3s_64 pr we introduce a variable that tells us which endianness the
shared struct is in and route every access to it through helper inline
functions that evaluate this variable.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index bb1e38a23ac7..f52f65694527 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -268,9 +268,10 @@ static inline ulong kvmppc_get_pc(struct kvm_vcpu *vcpu)
 	return vcpu->arch.pc;
 }
 
+static inline u64 kvmppc_get_msr(struct kvm_vcpu *vcpu);
 static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
 {
-	return (vcpu->arch.shared->msr & MSR_LE) != (MSR_KERNEL & MSR_LE);
+	return (kvmppc_get_msr(vcpu) & MSR_LE) != (MSR_KERNEL & MSR_LE);
 }
 
 static inline u32 kvmppc_get_last_inst_internal(struct kvm_vcpu *vcpu, ulong pc)