KVM: PPC: e500mc: Add doorbell emulation support

When one vcpu wants to kick another, it can issue a special IPI instruction
called msgsnd. This patch emulates this instruction, its clearing counterpart
and the infrastructure required to actually trigger that interrupt inside
a guest vcpu.

With this patch, SMP guests on e500mc work.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 72 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
index d7365b01f0c4..154c067761b1 100644
--- a/arch/powerpc/include/asm/dbell.h
+++ b/arch/powerpc/include/asm/dbell.h
@@ -19,7 +19,9 @@
 
 #define PPC_DBELL_MSG_BRDCAST   (0x04000000)
 #define PPC_DBELL_TYPE(x)       (((x) & 0xf) << (63-36))
+#define PPC_DBELL_TYPE_MASK     PPC_DBELL_TYPE(0xf)
 #define PPC_DBELL_LPID(x)       ((x) << (63 - 49))
+#define PPC_DBELL_PIR_MASK      0x3fff
 enum ppc_dbell {
         PPC_DBELL = 0,          /* doorbell */
         PPC_DBELL_CRIT = 1,     /* critical doorbell */
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 0b77be187cf7..85bd5b8f3fd5 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -326,6 +326,7 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
                 int_class = INT_CLASS_NONCRIT;
                 break;
         case BOOKE_IRQPRIO_CRITICAL:
+        case BOOKE_IRQPRIO_DBELL_CRIT:
                 allowed = vcpu->arch.shared->msr & MSR_CE;
                 allowed = allowed && !crit;
                 msr_mask = MSR_GS | MSR_ME;
@@ -342,6 +343,7 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
                 keep_irq = true;
                 /* fall through */
         case BOOKE_IRQPRIO_EXTERNAL:
+        case BOOKE_IRQPRIO_DBELL:
                 allowed = vcpu->arch.shared->msr & MSR_EE;
                 allowed = allowed && !crit;
                 msr_mask = MSR_GS | MSR_CE | MSR_ME | MSR_DE;
diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
index 98b6c1cd6b82..99155f847a6a 100644
--- a/arch/powerpc/kvm/e500_emulate.c
+++ b/arch/powerpc/kvm/e500_emulate.c
@@ -14,16 +14,74 @@
 
 #include <asm/kvm_ppc.h>
 #include <asm/disassemble.h>
+#include <asm/dbell.h>
 
 #include "booke.h"
 #include "e500.h"
 
+#define XOP_MSGSND  206
+#define XOP_MSGCLR  238
 #define XOP_TLBIVAX 786
 #define XOP_TLBSX   914
 #define XOP_TLBRE   946
 #define XOP_TLBWE   978
 #define XOP_TLBILX  18
 
+#ifdef CONFIG_KVM_E500MC
+static int dbell2prio(ulong param)
+{
+        int msg = param & PPC_DBELL_TYPE_MASK;
+        int prio = -1;
+
+        switch (msg) {
+        case PPC_DBELL_TYPE(PPC_DBELL):
+                prio = BOOKE_IRQPRIO_DBELL;
+                break;
+        case PPC_DBELL_TYPE(PPC_DBELL_CRIT):
+                prio = BOOKE_IRQPRIO_DBELL_CRIT;
+                break;
+        default:
+                break;
+        }
+
+        return prio;
+}
+
+static int kvmppc_e500_emul_msgclr(struct kvm_vcpu *vcpu, int rb)
+{
+        ulong param = vcpu->arch.gpr[rb];
+        int prio = dbell2prio(param);
+
+        if (prio < 0)
+                return EMULATE_FAIL;
+
+        clear_bit(prio, &vcpu->arch.pending_exceptions);
+        return EMULATE_DONE;
+}
+
+static int kvmppc_e500_emul_msgsnd(struct kvm_vcpu *vcpu, int rb)
+{
+        ulong param = vcpu->arch.gpr[rb];
+        int prio = dbell2prio(rb);
+        int pir = param & PPC_DBELL_PIR_MASK;
+        int i;
+        struct kvm_vcpu *cvcpu;
+
+        if (prio < 0)
+                return EMULATE_FAIL;
+
+        kvm_for_each_vcpu(i, cvcpu, vcpu->kvm) {
+                int cpir = cvcpu->arch.shared->pir;
+                if ((param & PPC_DBELL_MSG_BRDCAST) || (cpir == pir)) {
+                        set_bit(prio, &cvcpu->arch.pending_exceptions);
+                        kvm_vcpu_kick(cvcpu);
+                }
+        }
+
+        return EMULATE_DONE;
+}
+#endif
+
 int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
                            unsigned int inst, int *advance)
 {
@@ -36,6 +94,16 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
         case 31:
                 switch (get_xop(inst)) {
 
+#ifdef CONFIG_KVM_E500MC
+                case XOP_MSGSND:
+                        emulated = kvmppc_e500_emul_msgsnd(vcpu, get_rb(inst));
+                        break;
+
+                case XOP_MSGCLR:
+                        emulated = kvmppc_e500_emul_msgclr(vcpu, get_rb(inst));
+                        break;
+#endif
+
                 case XOP_TLBRE:
                         emulated = kvmppc_e500_emul_tlbre(vcpu);
                         break;