[PATCH v10 09/16] s390x: protvirt: SCLP interpretation

[Janosch Frank <frankja@linux.ibm.com>]

SCLP for a protected guest is done over the SIDAD, so we need to use
the s390_cpu_pv_mem_* functions to access the SIDAD instead of guest
memory when reading/writing SCBs.

To not confuse the sclp emulation, we set 0x4000 as the SCCB address,
since the function that injects the sclp external interrupt would
reject a zero sccb address.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 hw/s390x/sclp.c         | 65 ++++++++++++++++++++++++++++++++++-------
 include/hw/s390x/sclp.h |  2 ++
 target/s390x/kvm.c      | 25 ++++++++++++----
 3 files changed, 76 insertions(+), 16 deletions(-)

diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
index af0bfbc2eca74767..6486890fecea4b3c 100644
--- a/hw/s390x/sclp.c
+++ b/hw/s390x/sclp.c
@@ -33,6 +33,22 @@ static inline SCLPDevice *get_sclp_device(void)
     return sclp;
 }
 
+static inline bool sclp_command_code_valid(uint32_t code)
+{
+    switch (code & SCLP_CMD_CODE_MASK) {
+    case SCLP_CMDW_READ_SCP_INFO:
+    case SCLP_CMDW_READ_SCP_INFO_FORCED:
+    case SCLP_CMDW_READ_CPU_INFO:
+    case SCLP_CMDW_CONFIGURE_IOA:
+    case SCLP_CMDW_DECONFIGURE_IOA:
+    case SCLP_CMD_READ_EVENT_DATA:
+    case SCLP_CMD_WRITE_EVENT_DATA:
+    case SCLP_CMD_WRITE_EVENT_MASK:
+        return true;
+    }
+    return false;
+}
+
 static void prepare_cpu_entries(SCLPDevice *sclp, CPUEntry *entry, int *count)
 {
     MachineState *ms = MACHINE(qdev_get_machine());
@@ -193,6 +209,43 @@ static void sclp_execute(SCLPDevice *sclp, SCCB *sccb, uint32_t code)
     }
 }
 
+/*
+ * We only need the address to have something valid for the
+ * service_interrupt call.
+ */
+#define SCLP_PV_DUMMY_ADDR 0x4000
+int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb,
+                                uint32_t code)
+{
+    SCLPDevice *sclp = get_sclp_device();
+    SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp);
+    SCCB work_sccb;
+    hwaddr sccb_len = sizeof(SCCB);
+
+    /*
+     * Only a very limited number of calls is permitted by the
+     * Ultravisor and we support all of them, so we don't check for
+     * them. All other specification exceptions are also interpreted
+     * by the Ultravisor and hence never cause an exit we need to
+     * handle.
+     *
+     * Setting the CC is also done by the Ultravisor.
+     */
+    s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, sccb_len);
+
+    if (!sclp_command_code_valid(code)) {
+        work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
+        goto out_write;
+    }
+
+    sclp_c->execute(sclp, &work_sccb, code);
+out_write:
+    s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb,
+                          be16_to_cpu(work_sccb.h.length));
+    sclp_c->service_interrupt(sclp, SCLP_PV_DUMMY_ADDR);
+    return 0;
+}
+
 int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
 {
     SCLPDevice *sclp = get_sclp_device();
@@ -225,17 +278,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
         return -PGM_SPECIFICATION;
     }
 
-    switch (code & SCLP_CMD_CODE_MASK) {
-    case SCLP_CMDW_READ_SCP_INFO:
-    case SCLP_CMDW_READ_SCP_INFO_FORCED:
-    case SCLP_CMDW_READ_CPU_INFO:
-    case SCLP_CMDW_CONFIGURE_IOA:
-    case SCLP_CMDW_DECONFIGURE_IOA:
-    case SCLP_CMD_READ_EVENT_DATA:
-    case SCLP_CMD_WRITE_EVENT_DATA:
-    case SCLP_CMD_WRITE_EVENT_MASK:
-        break;
-    default:
+    if (!sclp_command_code_valid(code)) {
         work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
         goto out_write;
     }
diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index cd7b24359f28deb4..822eff4396ff5dde 100644
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -217,5 +217,7 @@ void s390_sclp_init(void);
 void sclp_service_interrupt(uint32_t sccb);
 void raise_irq_cpu_hotplug(void);
 int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code);
+int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb,
+                                uint32_t code);
 
 #endif
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 462a1d70ee78104c..6b7819d2c51a111c 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -1233,12 +1233,27 @@ static void kvm_sclp_service_call(S390CPU *cpu, struct kvm_run *run,
     sccb = env->regs[ipbh0 & 0xf];
     code = env->regs[(ipbh0 & 0xf0) >> 4];
 
-    r = sclp_service_call(env, sccb, code);
-    if (r < 0) {
-        kvm_s390_program_interrupt(cpu, -r);
-        return;
+    switch (run->s390_sieic.icptcode) {
+    case ICPT_PV_INSTR_NOTIFICATION:
+        g_assert(s390_is_pv());
+        /* The notification intercepts are currently handled by KVM */
+        error_report("unexpected SCLP PV notification");
+        exit(1);
+        break;
+    case ICPT_PV_INSTR:
+        g_assert(s390_is_pv());
+        sclp_service_call_protected(env, sccb, code);
+        /* Setting the CC is done by the Ultravisor. */
+        break;
+    case ICPT_INSTRUCTION:
+        g_assert(!s390_is_pv());
+        r = sclp_service_call(env, sccb, code);
+        if (r < 0) {
+            kvm_s390_program_interrupt(cpu, -r);
+            return;
+        }
+        setcc(cpu, r);
     }
-    setcc(cpu, r);
 }
 
 static int handle_b2(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
-- 
2.25.1