target-ppc: Add mechanism for synchronizing SPRs with KVM

Currently when runing under KVM on ppc, we synchronize a certain number of
vital SPRs to KVM through the SET_SREGS call.  This leaves out quite a lot
of important SPRs which are maintained in KVM.  It would be helpful to
have their contents in qemu for debugging purposes, and when we implement
migration it will be vital, since they include important guest state that
will need to be restored on the target.

This patch sets up for synchronization of any registers supported by the
KVM ONE_REG calls.  A new variant on spr_register() allows a ONE_REG id to
be stored with the SPR information.  When we set/get information to KVM
we also synchronize any SPRs so registered.

For now we set this mechanism up to synchronize a handful of important
registers that already have ONE_REG IDs, notably the DAR and DSISR.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 107 insertions, 8 deletions

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index a89c3cf..02ab559 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -61,6 +61,7 @@ static int cap_ppc_smt;
 static int cap_ppc_rma;
 static int cap_spapr_tce;
 static int cap_hior;
+static int cap_one_reg;
 
 /* XXX We have a race condition where we actually have a level triggered
  *     interrupt, but the infrastructure can't expose that yet, so the guest
@@ -89,6 +90,7 @@ int kvm_arch_init(KVMState *s)
     cap_ppc_smt = kvm_check_extension(s, KVM_CAP_PPC_SMT);
     cap_ppc_rma = kvm_check_extension(s, KVM_CAP_PPC_RMA);
     cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
+    cap_one_reg = kvm_check_extension(s, KVM_CAP_ONE_REG);
     cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
 
     if (!cap_interrupt_level) {
@@ -449,6 +451,76 @@ static void kvm_sw_tlb_put(PowerPCCPU *cpu)
     g_free(bitmap);
 }
 
+static void kvm_get_one_spr(CPUState *cs, uint64_t id, int spr)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    CPUPPCState *env = &cpu->env;
+    union {
+        uint32_t u32;
+        uint64_t u64;
+    } val;
+    struct kvm_one_reg reg = {
+        .id = id,
+        .addr = (uintptr_t) &val,
+    };
+    int ret;
+
+    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &reg);
+    if (ret != 0) {
+        fprintf(stderr, "Warning: Unable to retrieve SPR %d from KVM: %s\n",
+                spr, strerror(errno));
+    } else {
+        switch (id & KVM_REG_SIZE_MASK) {
+        case KVM_REG_SIZE_U32:
+            env->spr[spr] = val.u32;
+            break;
+
+        case KVM_REG_SIZE_U64:
+            env->spr[spr] = val.u64;
+            break;
+
+        default:
+            /* Don't handle this size yet */
+            abort();
+        }
+    }
+}
+
+static void kvm_put_one_spr(CPUState *cs, uint64_t id, int spr)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    CPUPPCState *env = &cpu->env;
+    union {
+        uint32_t u32;
+        uint64_t u64;
+    } val;
+    struct kvm_one_reg reg = {
+        .id = id,
+        .addr = (uintptr_t) &val,
+    };
+    int ret;
+
+    switch (id & KVM_REG_SIZE_MASK) {
+    case KVM_REG_SIZE_U32:
+        val.u32 = env->spr[spr];
+        break;
+
+    case KVM_REG_SIZE_U64:
+        val.u64 = env->spr[spr];
+        break;
+
+    default:
+        /* Don't handle this size yet */
+        abort();
+    }
+
+    ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
+    if (ret != 0) {
+        fprintf(stderr, "Warning: Unable to set SPR %d to KVM: %s\n",
+                spr, strerror(errno));
+    }
+}
+
 int kvm_arch_put_registers(CPUState *cs, int level)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
@@ -530,15 +602,22 @@ int kvm_arch_put_registers(CPUState *cs, int level)
     }
 
     if (cap_hior && (level >= KVM_PUT_RESET_STATE)) {
-        uint64_t hior = env->spr[SPR_HIOR];
-        struct kvm_one_reg reg = {
-            .id = KVM_REG_PPC_HIOR,
-            .addr = (uintptr_t) &hior,
-        };
+        kvm_put_one_spr(cs, KVM_REG_PPC_HIOR, SPR_HIOR);
+    }
 
-        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
-        if (ret) {
-            return ret;
+    if (cap_one_reg) {
+        int i;
+
+        /* We deliberately ignore errors here, for kernels which have
+         * the ONE_REG calls, but don't support the specific
+         * registers, there's a reasonable chance things will still
+         * work, at least until we try to migrate. */
+        for (i = 0; i < 1024; i++) {
+            uint64_t id = env->spr_cb[i].one_reg_id;
+
+            if (id != 0) {
+                kvm_put_one_spr(cs, id, i);
+            }
         }
     }
 
@@ -721,6 +800,26 @@ int kvm_arch_get_registers(CPUState *cs)
         }
     }
 
+    if (cap_hior) {
+        kvm_get_one_spr(cs, KVM_REG_PPC_HIOR, SPR_HIOR);
+    }
+
+    if (cap_one_reg) {
+        int i;
+
+        /* We deliberately ignore errors here, for kernels which have
+         * the ONE_REG calls, but don't support the specific
+         * registers, there's a reasonable chance things will still
+         * work, at least until we try to migrate. */
+        for (i = 0; i < 1024; i++) {
+            uint64_t id = env->spr_cb[i].one_reg_id;
+
+            if (id != 0) {
+                kvm_get_one_spr(cs, id, i);
+            }
+        }
+    }
+
     return 0;
 }