KVM: PPC: Book3S: MMIO emulation support for little endian guests

MMIO emulation reads the last instruction executed by the guest
and then emulates. If the guest is running in Little Endian order,
or more generally in a different endian order of the host, the
instruction needs to be byte-swapped before being emulated.

This patch adds a helper routine which tests the endian order of
the host and the guest in order to decide whether a byteswap is
needed or not. It is then used to byteswap the last instruction
of the guest in the endian order of the host before MMIO emulation
is performed.

Finally, kvmppc_handle_load() of kvmppc_handle_store() are modified
to reverse the endianness of the MMIO if required.

Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
[agraf: add booke handling]
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_booke.h b/arch/powerpc/include/asm/kvm_booke.h
index dd8f61510dfd..80d46b5a7efb 100644
--- a/arch/powerpc/include/asm/kvm_booke.h
+++ b/arch/powerpc/include/asm/kvm_booke.h
@@ -63,6 +63,12 @@ static inline u32 kvmppc_get_xer(struct kvm_vcpu *vcpu)
 	return vcpu->arch.xer;
 }
 
+static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
+{
+	/* XXX Would need to check TLB entry */
+	return false;
+}
+
 static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.last_inst;