KVM: PPC: e500: use hardware hint when loading TLB0 entries

The hardware maintains a per-set next victim hint.  Using this
reduces conflicts, especially on e500v2 where a single guest
TLB entry is mapped to two shadow TLB entries (user and kernel).
We want those two entries to go to different TLB ways.

sesel is now only used for TLB1.

Reported-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/include/asm/mmu-book3e.h

@@ -41,9 +41,10 @@
 /* MAS registers bit definitions */
 
 #define MAS0_TLBSEL(x)		(((x) << 28) & 0x30000000)
-#define MAS0_ESEL(x)		(((x) << 16) & 0x0FFF0000)
-#define MAS0_NV(x)		((x) & 0x00000FFF)
 #define MAS0_ESEL_MASK		0x0FFF0000
+#define MAS0_ESEL_SHIFT		16
+#define MAS0_ESEL(x)		(((x) << MAS0_ESEL_SHIFT) & MAS0_ESEL_MASK)
+#define MAS0_NV(x)		((x) & 0x00000FFF)
 #define MAS0_HES		0x00004000
 #define MAS0_WQ_ALLWAYS		0x00000000
 #define MAS0_WQ_COND		0x00001000

arch/powerpc/kvm/e500_tlb.c

@@ -296,17 +296,41 @@ static inline void __write_host_tlbe(struct kvm_book3e_206_tlb_entry *stlbe,
 	local_irq_restore(flags);
 }
 
-/* esel is index into set, not whole array */
+/*
+ * Acquire a mas0 with victim hint, as if we just took a TLB miss.
+ *
+ * We don't care about the address we're searching for, other than that it's
+ * in the right set and is not present in the TLB.  Using a zero PID and a
+ * userspace address means we don't have to set and then restore MAS5, or
+ * calculate a proper MAS6 value.
+ */
+static u32 get_host_mas0(unsigned long eaddr)
+{
+	unsigned long flags;
+	u32 mas0;
+
+	local_irq_save(flags);
+	mtspr(SPRN_MAS6, 0);
+	asm volatile("tlbsx 0, %0" : : "b" (eaddr & ~CONFIG_PAGE_OFFSET));
+	mas0 = mfspr(SPRN_MAS0);
+	local_irq_restore(flags);
+
+	return mas0;
+}
+
+/* sesel is for tlb1 only */
 static inline void write_host_tlbe(struct kvmppc_vcpu_e500 *vcpu_e500,
-		int tlbsel, int esel, struct kvm_book3e_206_tlb_entry *stlbe)
+		int tlbsel, int sesel, struct kvm_book3e_206_tlb_entry *stlbe)
 {
+	u32 mas0;
+
 	if (tlbsel == 0) {
-		int way = esel & (vcpu_e500->gtlb_params[0].ways - 1);
-		__write_host_tlbe(stlbe, MAS0_TLBSEL(0) | MAS0_ESEL(way));
+		mas0 = get_host_mas0(stlbe->mas2);
+		__write_host_tlbe(stlbe, mas0);
 	} else {
 		__write_host_tlbe(stlbe,
 				  MAS0_TLBSEL(1) |
-				  MAS0_ESEL(to_htlb1_esel(esel)));
+				  MAS0_ESEL(to_htlb1_esel(sesel)));
 	}
 	trace_kvm_stlb_write(index_of(tlbsel, esel), stlbe->mas1, stlbe->mas2,
 			     (u32)stlbe->mas7_3, (u32)(stlbe->mas7_3 >> 32));
@@ -422,12 +446,6 @@ static int gtlb0_set_base(struct kvmppc_vcpu_e500 *vcpu_e500, gva_t addr)
 			     vcpu_e500->gtlb_params[0].ways);
 }
 
-static int htlb0_set_base(gva_t addr)
-{
-	return tlb0_set_base(addr, host_tlb_params[0].sets,
-			     host_tlb_params[0].ways);
-}
-
 static unsigned int get_tlb_esel(struct kvm_vcpu *vcpu, int tlbsel)
 {
 	struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
@@ -585,10 +603,9 @@ static inline void kvmppc_e500_setup_stlbe(
 				vcpu_e500->vcpu.arch.shared->msr & MSR_PR);
 }
 
-/* sesel is an index into the entire array, not just the set */
 static inline void kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 	u64 gvaddr, gfn_t gfn, struct kvm_book3e_206_tlb_entry *gtlbe,
-	int tlbsel, int sesel, struct kvm_book3e_206_tlb_entry *stlbe,
+	int tlbsel, struct kvm_book3e_206_tlb_entry *stlbe,
 	struct tlbe_ref *ref)
 {
 	struct kvm_memory_slot *slot;
@@ -721,27 +738,19 @@ static inline void kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 }
 
 /* XXX only map the one-one case, for now use TLB0 */
-static int kvmppc_e500_tlb0_map(struct kvmppc_vcpu_e500 *vcpu_e500,
-				int esel,
-				struct kvm_book3e_206_tlb_entry *stlbe)
+static void kvmppc_e500_tlb0_map(struct kvmppc_vcpu_e500 *vcpu_e500,
+				 int esel,
+				 struct kvm_book3e_206_tlb_entry *stlbe)
 {
 	struct kvm_book3e_206_tlb_entry *gtlbe;
 	struct tlbe_ref *ref;
-	int sesel = esel & (host_tlb_params[0].ways - 1);
-	int sesel_base;
-	gva_t ea;
 
 	gtlbe = get_entry(vcpu_e500, 0, esel);
 	ref = &vcpu_e500->gtlb_priv[0][esel].ref;
 
-	ea = get_tlb_eaddr(gtlbe);
-	sesel_base = htlb0_set_base(ea);
-
 	kvmppc_e500_shadow_map(vcpu_e500, get_tlb_eaddr(gtlbe),
 			get_tlb_raddr(gtlbe) >> PAGE_SHIFT,
-			gtlbe, 0, sesel_base + sesel, stlbe, ref);
-
-	return sesel;
+			gtlbe, 0, stlbe, ref);
 }
 
 /* Caller must ensure that the specified guest TLB entry is safe to insert into
@@ -760,8 +769,7 @@ static int kvmppc_e500_tlb1_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 		vcpu_e500->host_tlb1_nv = 0;
 
 	ref = &vcpu_e500->tlb_refs[1][victim];
-	kvmppc_e500_shadow_map(vcpu_e500, gvaddr, gfn, gtlbe, 1,
-			       victim, stlbe, ref);
+	kvmppc_e500_shadow_map(vcpu_e500, gvaddr, gfn, gtlbe, 1, stlbe, ref);
 
 	return victim;
 }
@@ -910,7 +918,7 @@ int kvmppc_e500_emul_tlbsx(struct kvm_vcpu *vcpu, int rb)
 	return EMULATE_DONE;
 }
 
-/* sesel is index into the set, not the whole array */
+/* sesel is for tlb1 only */
 static void write_stlbe(struct kvmppc_vcpu_e500 *vcpu_e500,
 			struct kvm_book3e_206_tlb_entry *gtlbe,
 			struct kvm_book3e_206_tlb_entry *stlbe,
@@ -963,7 +971,8 @@ int kvmppc_e500_emul_tlbwe(struct kvm_vcpu *vcpu)
 			gtlbe->mas1 |= MAS1_TSIZE(BOOK3E_PAGESZ_4K);
 
 			stlbsel = 0;
-			sesel = kvmppc_e500_tlb0_map(vcpu_e500, esel, &stlbe);
+			kvmppc_e500_tlb0_map(vcpu_e500, esel, &stlbe);
+			sesel = 0; /* unused */
 
 			break;
 
@@ -1052,7 +1061,7 @@ void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 eaddr, gpa_t gpaddr,
 	switch (tlbsel) {
 	case 0:
 		stlbsel = 0;
-		sesel = esel & (host_tlb_params[0].ways - 1);
+		sesel = 0; /* unused */
 		priv = &vcpu_e500->gtlb_priv[tlbsel][esel];
 
 		kvmppc_e500_setup_stlbe(vcpu_e500, gtlbe, BOOK3E_PAGESZ_4K,