KVM: PPC: Implement correct SID mapping on Book3s_32

Up until now we were doing segment mappings wrong on Book3s_32. For Book3s_64
we were using a trick where we know that a single mmu_context gives us 16 bits
of context ids.

The mm system on Book3s_32 instead uses a clever algorithm to distribute VSIDs
across the available range, so a context id really only gives us 16 available
VSIDs.

To keep at least a few guest processes in the SID shadow, let's map a number of
contexts that we can use as VSID pool. This makes the code be actually correct
and shouldn't hurt performance too much.

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index be8aac24ba83f0383b4899acb748929a37ab0bbd..d62e703f1214e04a5f06de518ae61af33ceb2eb4 100644 (file)
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -60,6 +60,13 @@ struct kvmppc_sid_map {
 #define SID_MAP_NUM     (1 << SID_MAP_BITS)
 #define SID_MAP_MASK    (SID_MAP_NUM - 1)
 
+#ifdef CONFIG_PPC_BOOK3S_64
+#define SID_CONTEXTS   1
+#else
+#define SID_CONTEXTS   128
+#define VSID_POOL_SIZE (SID_CONTEXTS * 16)
+#endif
+
 struct kvmppc_vcpu_book3s {
        struct kvm_vcpu vcpu;
        struct kvmppc_book3s_shadow_vcpu *shadow_vcpu;
@@ -78,10 +85,14 @@ struct kvmppc_vcpu_book3s {
        u64 sdr1;
        u64 hior;
        u64 msr_mask;
-       u64 vsid_first;
        u64 vsid_next;
+#ifdef CONFIG_PPC_BOOK3S_32
+       u32 vsid_pool[VSID_POOL_SIZE];
+#else
+       u64 vsid_first;
        u64 vsid_max;
-       int context_id;
+#endif
+       int context_id[SID_CONTEXTS];
        ulong prog_flags; /* flags to inject when giving a 700 trap */
 };
 

diff --git a/arch/powerpc/kvm/book3s_32_mmu_host.c b/arch/powerpc/kvm/book3s_32_mmu_host.c
index 57dddeb23b9b90383964c6b42ef833d75ba68f76..9fecbfbce773205650a9d6d9cd77704a61757a38 100644 (file)
--- a/arch/powerpc/kvm/book3s_32_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_32_mmu_host.c
@@ -275,18 +275,15 @@ static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
        backwards_map = !backwards_map;
 
        /* Uh-oh ... out of mappings. Let's flush! */
-       if (vcpu_book3s->vsid_next >= vcpu_book3s->vsid_max) {
-               vcpu_book3s->vsid_next = vcpu_book3s->vsid_first;
+       if (vcpu_book3s->vsid_next >= VSID_POOL_SIZE) {
+               vcpu_book3s->vsid_next = 0;
                memset(vcpu_book3s->sid_map, 0,
                       sizeof(struct kvmppc_sid_map) * SID_MAP_NUM);
                kvmppc_mmu_pte_flush(vcpu, 0, 0);
                kvmppc_mmu_flush_segments(vcpu);
        }
-       map->host_vsid = vcpu_book3s->vsid_next;
-
-       /* Would have to be 111 to be completely aligned with the rest of
-          Linux, but that is just way too little space! */
-       vcpu_book3s->vsid_next+=1;
+       map->host_vsid = vcpu_book3s->vsid_pool[vcpu_book3s->vsid_next];
+       vcpu_book3s->vsid_next++;
 
        map->guest_vsid = gvsid;
        map->valid = true;
@@ -333,40 +330,38 @@ void kvmppc_mmu_flush_segments(struct kvm_vcpu *vcpu)
 
 void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu)
 {
+       int i;
+
        kvmppc_mmu_hpte_destroy(vcpu);
        preempt_disable();
-       __destroy_context(to_book3s(vcpu)->context_id);
+       for (i = 0; i < SID_CONTEXTS; i++)
+               __destroy_context(to_book3s(vcpu)->context_id[i]);
        preempt_enable();
 }
 
 /* From mm/mmu_context_hash32.c */
-#define CTX_TO_VSID(ctx) (((ctx) * (897 * 16)) & 0xffffff)
+#define CTX_TO_VSID(c, id)     ((((c) * (897 * 16)) + (id * 0x111)) & 0xffffff)
 
 int kvmppc_mmu_init(struct kvm_vcpu *vcpu)
 {
        struct kvmppc_vcpu_book3s *vcpu3s = to_book3s(vcpu);
        int err;
        ulong sdr1;
+       int i;
+       int j;
 
-       err = __init_new_context();
-       if (err < 0)
-               return -1;
-       vcpu3s->context_id = err;
-
-       vcpu3s->vsid_max = CTX_TO_VSID(vcpu3s->context_id + 1) - 1;
-       vcpu3s->vsid_first = CTX_TO_VSID(vcpu3s->context_id);
-
-#if 0 /* XXX still doesn't guarantee uniqueness */
-       /* We could collide with the Linux vsid space because the vsid
-        * wraps around at 24 bits. We're safe if we do our own space
-        * though, so let's always set the highest bit. */
+       for (i = 0; i < SID_CONTEXTS; i++) {
+               err = __init_new_context();
+               if (err < 0)
+                       goto init_fail;
+               vcpu3s->context_id[i] = err;
 
-       vcpu3s->vsid_max |= 0x00800000;
-       vcpu3s->vsid_first |= 0x00800000;
-#endif
-       BUG_ON(vcpu3s->vsid_max < vcpu3s->vsid_first);
+               /* Remember context id for this combination */
+               for (j = 0; j < 16; j++)
+                       vcpu3s->vsid_pool[(i * 16) + j] = CTX_TO_VSID(err, j);
+       }
 
-       vcpu3s->vsid_next = vcpu3s->vsid_first;
+       vcpu3s->vsid_next = 0;
 
        /* Remember where the HTAB is */
        asm ( "mfsdr1 %0" : "=r"(sdr1) );
@@ -376,4 +371,14 @@ int kvmppc_mmu_init(struct kvm_vcpu *vcpu)
        kvmppc_mmu_hpte_init(vcpu);
 
        return 0;
+
+init_fail:
+       for (j = 0; j < i; j++) {
+               if (!vcpu3s->context_id[j])
+                       continue;
+
+               __destroy_context(to_book3s(vcpu)->context_id[j]);
+       }
+
+       return -1;
 }

diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index 4040c8d16ad5e5375753d745cee835d3c2c86d89..fa2f08434ba5c5c867166262388c8dab0a86aca1 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -286,7 +286,7 @@ void kvmppc_mmu_flush_segments(struct kvm_vcpu *vcpu)
 void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu)
 {
        kvmppc_mmu_hpte_destroy(vcpu);
-       __destroy_context(to_book3s(vcpu)->context_id);
+       __destroy_context(to_book3s(vcpu)->context_id[0]);
 }
 
 int kvmppc_mmu_init(struct kvm_vcpu *vcpu)
@@ -297,10 +297,10 @@ int kvmppc_mmu_init(struct kvm_vcpu *vcpu)
        err = __init_new_context();
        if (err < 0)
                return -1;
-       vcpu3s->context_id = err;
+       vcpu3s->context_id[0] = err;
 
-       vcpu3s->vsid_max = ((vcpu3s->context_id + 1) << USER_ESID_BITS) - 1;
-       vcpu3s->vsid_first = vcpu3s->context_id << USER_ESID_BITS;
+       vcpu3s->vsid_max = ((vcpu3s->context_id[0] + 1) << USER_ESID_BITS) - 1;
+       vcpu3s->vsid_first = vcpu3s->context_id[0] << USER_ESID_BITS;
        vcpu3s->vsid_next = vcpu3s->vsid_first;
 
        kvmppc_mmu_hpte_init(vcpu);