KVM: PPC: Convert MSR to shared page

One of the most obvious registers to share with the guest directly is the
MSR. The MSR contains the "interrupts enabled" flag which the guest has to
toggle in critical sections.

So in order to bring the overhead of interrupt en- and disabling down, let's
put msr into the shared page. Keep in mind that even though you can fully read
its contents, writing to it doesn't always update all state. There are a few
safe fields that don't require hypervisor interaction. See the documentation
for a list of MSR bits that are safe to be set from inside the guest.

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

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/powerpc/kvm/44x_tlb.c b/arch/powerpc/kvm/44x_tlb.c
index 9b9b5cdea840..9f71b8d6eb0d 100644
--- a/arch/powerpc/kvm/44x_tlb.c
+++ b/arch/powerpc/kvm/44x_tlb.c
@@ -221,14 +221,14 @@ gpa_t kvmppc_mmu_xlate(struct kvm_vcpu *vcpu, unsigned int gtlb_index,
 
 int kvmppc_mmu_itlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
 {
-	unsigned int as = !!(vcpu->arch.msr & MSR_IS);
+	unsigned int as = !!(vcpu->arch.shared->msr & MSR_IS);
 
 	return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
 }
 
 int kvmppc_mmu_dtlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
 {
-	unsigned int as = !!(vcpu->arch.msr & MSR_DS);
+	unsigned int as = !!(vcpu->arch.shared->msr & MSR_DS);
 
 	return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
 }
@@ -354,7 +354,7 @@ void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gpa_t gpaddr,
 
 	stlbe.word1 = (hpaddr & 0xfffffc00) | ((hpaddr >> 32) & 0xf);
 	stlbe.word2 = kvmppc_44x_tlb_shadow_attrib(flags,
-	                                            vcpu->arch.msr & MSR_PR);
+	                                            vcpu->arch.shared->msr & MSR_PR);
 	stlbe.tid = !(asid & 0xff);
 
 	/* Keep track of the reference so we can properly release it later. */
@@ -423,7 +423,7 @@ static int tlbe_is_host_safe(const struct kvm_vcpu *vcpu,
 
 	/* Does it match current guest AS? */
 	/* XXX what about IS != DS? */
-	if (get_tlb_ts(tlbe) != !!(vcpu->arch.msr & MSR_IS))
+	if (get_tlb_ts(tlbe) != !!(vcpu->arch.shared->msr & MSR_IS))
 		return 0;
 
 	gpa = get_tlb_raddr(tlbe);