KVM: ppc: Write only modified shadow entries into the TLB on exit

Track which TLB entries need to be written, instead of overwriting everything
below the high water mark. Typically only a single guest TLB entry will be
modified in a single exit.

Guest boot time performance improvement: about 15%.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 6 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index dc3a7562bae4..4338b03da8f9 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -82,6 +82,9 @@ struct kvm_vcpu_arch {
         /* Pages which are referenced in the shadow TLB. */
         struct page *shadow_pages[PPC44x_TLB_SIZE];
 
+        /* Track which TLB entries we've modified in the current exit. */
+        u8 shadow_tlb_mod[PPC44x_TLB_SIZE];
+
         u32 host_stack;
         u32 host_pid;
         u32 host_dbcr0;
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index a8b068792260..8e7e42959903 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -65,6 +65,9 @@ extern void kvmppc_mmu_invalidate(struct kvm_vcpu *vcpu, gva_t eaddr,
                                   gva_t eend, u32 asid);
 extern void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode);
 
+/* XXX Book E specific */
+extern void kvmppc_tlbe_set_modified(struct kvm_vcpu *vcpu, unsigned int i);
+
 extern void kvmppc_check_and_deliver_interrupts(struct kvm_vcpu *vcpu);
 
 static inline void kvmppc_queue_exception(struct kvm_vcpu *vcpu, int exception)