KVM: PPC: Book3S: PR: Enable alternative instruction for SC 1

When running on top of pHyp, the hypercall instruction "sc 1" goes
straight into pHyp without trapping in supervisor mode.

So if we want to support PAPR guest in this configuration we need to
add a second way of accessing PAPR hypercalls, preferably with the
exact same semantics except for the instruction.

So let's overlay an officially reserved instruction and emulate PAPR
hypercalls whenever we hit that one.

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

3 files changed, 34 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 572aa7530619..5f5f69abd281 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -44,6 +44,7 @@ enum emulation_result {
         EMULATE_DO_DCR,       /* kvm_run filled with DCR request */
         EMULATE_FAIL,         /* can't emulate this instruction */
         EMULATE_AGAIN,        /* something went wrong. go again */
+        EMULATE_DO_PAPR,      /* kvm_run filled with PAPR request */
 };
 
 extern int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index d31a716f7f2b..c88161bed8df 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -34,6 +34,8 @@
 #define OP_31_XOP_MTSRIN        242
 #define OP_31_XOP_TLBIEL        274
 #define OP_31_XOP_TLBIE         306
+/* Opcode is officially reserved, reuse it as sc 1 when sc 1 doesn't trap */
+#define OP_31_XOP_FAKE_SC1      308
 #define OP_31_XOP_SLBMTE        402
 #define OP_31_XOP_SLBIE         434
 #define OP_31_XOP_SLBIA         498
@@ -170,6 +172,32 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
                         vcpu->arch.mmu.tlbie(vcpu, addr, large);
                         break;
                 }
+#ifdef CONFIG_KVM_BOOK3S_64_PR
+                case OP_31_XOP_FAKE_SC1:
+                {
+                        /* SC 1 papr hypercalls */
+                        ulong cmd = kvmppc_get_gpr(vcpu, 3);
+                        int i;
+
+                        if ((vcpu->arch.shared->msr & MSR_PR) ||
+                            !vcpu->arch.papr_enabled) {
+                                emulated = EMULATE_FAIL;
+                                break;
+                        }
+
+                        if (kvmppc_h_pr(vcpu, cmd) == EMULATE_DONE)
+                                break;
+
+                        run->papr_hcall.nr = cmd;
+                        for (i = 0; i < 9; ++i) {
+                                ulong gpr = kvmppc_get_gpr(vcpu, 4 + i);
+                                run->papr_hcall.args[i] = gpr;
+                        }
+
+                        emulated = EMULATE_DO_PAPR;
+                        break;
+                }
+#endif
                 case OP_31_XOP_EIOIO:
                         break;
                 case OP_31_XOP_SLBMTE:
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 28d38adeca73..73ed11c41bac 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -760,6 +760,11 @@ program_interrupt:
                         run->exit_reason = KVM_EXIT_MMIO;
                         r = RESUME_HOST_NV;
                         break;
+                case EMULATE_DO_PAPR:
+                        run->exit_reason = KVM_EXIT_PAPR_HCALL;
+                        vcpu->arch.hcall_needed = 1;
+                        r = RESUME_HOST_NV;
+                        break;
                 default:
                         BUG();
                 }