KVM: ppc: save and restore guest mappings on context switch
Store shadow TLB entries in memory, but only use it on host context switch
(instead of every guest entry). This improves performance for most workloads on
440 by reducing the guest TLB miss rate.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/powerpc/kvm/44x_tlb.c b/arch/powerpc/kvm/44x_tlb.c
index 2981ebe..ff16d0e 100644
--- a/arch/powerpc/kvm/44x_tlb.c
+++ b/arch/powerpc/kvm/44x_tlb.c
@@ -73,6 +73,25 @@
);
}
+static inline void kvmppc_44x_tlbre(unsigned int index,
+ struct kvmppc_44x_tlbe *tlbe)
+{
+ asm volatile(
+ "tlbre %[word0], %[index], 0\n"
+ "mfspr %[tid], %[sprn_mmucr]\n"
+ "andi. %[tid], %[tid], 0xff\n"
+ "tlbre %[word1], %[index], 1\n"
+ "tlbre %[word2], %[index], 2\n"
+ : [word0] "=r"(tlbe->word0),
+ [word1] "=r"(tlbe->word1),
+ [word2] "=r"(tlbe->word2),
+ [tid] "=r"(tlbe->tid)
+ : [index] "r"(index),
+ [sprn_mmucr] "i"(SPRN_MMUCR)
+ : "cc"
+ );
+}
+
static inline void kvmppc_44x_tlbwe(unsigned int index,
struct kvmppc_44x_tlbe *stlbe)
{
@@ -116,6 +135,44 @@
return attrib;
}
+/* Load shadow TLB back into hardware. */
+void kvmppc_44x_tlb_load(struct kvm_vcpu *vcpu)
+{
+ struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
+ int i;
+
+ for (i = 0; i <= tlb_44x_hwater; i++) {
+ struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];
+
+ if (get_tlb_v(stlbe) && get_tlb_ts(stlbe))
+ kvmppc_44x_tlbwe(i, stlbe);
+ }
+}
+
+static void kvmppc_44x_tlbe_set_modified(struct kvmppc_vcpu_44x *vcpu_44x,
+ unsigned int i)
+{
+ vcpu_44x->shadow_tlb_mod[i] = 1;
+}
+
+/* Save hardware TLB to the vcpu, and invalidate all guest mappings. */
+void kvmppc_44x_tlb_put(struct kvm_vcpu *vcpu)
+{
+ struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
+ int i;
+
+ for (i = 0; i <= tlb_44x_hwater; i++) {
+ struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];
+
+ if (vcpu_44x->shadow_tlb_mod[i])
+ kvmppc_44x_tlbre(i, stlbe);
+
+ if (get_tlb_v(stlbe) && get_tlb_ts(stlbe))
+ kvmppc_44x_tlbie(i);
+ }
+}
+
+
/* Search the guest TLB for a matching entry. */
int kvmppc_44x_tlb_index(struct kvm_vcpu *vcpu, gva_t eaddr, unsigned int pid,
unsigned int as)
@@ -283,6 +340,7 @@
ref->tid = stlbe.tid;
/* Insert shadow mapping into hardware TLB. */
+ kvmppc_44x_tlbe_set_modified(vcpu_44x, victim);
kvmppc_44x_tlbwe(victim, &stlbe);
KVMTRACE_5D(STLB_WRITE, vcpu, victim, stlbe.tid, stlbe.word0, stlbe.word1,
stlbe.word2, handler);