s390x: Add SIDA memory ops

Protected guests save the instruction control blocks in the SIDA
instead of QEMU/KVM directly accessing the guest's memory.

Let's introduce new functions to access the SIDA.

The memops for doing so are available with KVM_CAP_S390_PROTECTED, so
let's check for that.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200319131921.2367-8-frankja@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

target/s390x/cpu.h

@@ -823,7 +823,12 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, uint8_t ar, void *hostbuf,
 #define s390_cpu_virt_mem_check_write(cpu, laddr, ar, len)   \
         s390_cpu_virt_mem_rw(cpu, laddr, ar, NULL, len, true)
 void s390_cpu_virt_mem_handle_exc(S390CPU *cpu, uintptr_t ra);
-
+int s390_cpu_pv_mem_rw(S390CPU *cpu, unsigned int offset, void *hostbuf,
+                       int len, bool is_write);
+#define s390_cpu_pv_mem_read(cpu, offset, dest, len)    \
+        s390_cpu_pv_mem_rw(cpu, offset, dest, len, false)
+#define s390_cpu_pv_mem_write(cpu, offset, dest, len)       \
+        s390_cpu_pv_mem_rw(cpu, offset, dest, len, true)
 
 /* sigp.c */
 int s390_cpu_restart(S390CPU *cpu);

target/s390x/kvm.c

@@ -154,6 +154,7 @@ static int cap_ri;
 static int cap_gs;
 static int cap_hpage_1m;
 static int cap_vcpu_resets;
+static int cap_protected;
 
 static int active_cmma;
 
@@ -351,6 +352,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
     cap_s390_irq = kvm_check_extension(s, KVM_CAP_S390_INJECT_IRQ);
     cap_vcpu_resets = kvm_check_extension(s, KVM_CAP_S390_VCPU_RESETS);
+    cap_protected = kvm_check_extension(s, KVM_CAP_S390_PROTECTED);
 
     if (!kvm_check_extension(s, KVM_CAP_S390_GMAP)
         || !kvm_check_extension(s, KVM_CAP_S390_COW)) {
@@ -851,6 +853,30 @@ int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, uint8_t ar, void *hostbuf,
     return ret;
 }
 
+int kvm_s390_mem_op_pv(S390CPU *cpu, uint64_t offset, void *hostbuf,
+                       int len, bool is_write)
+{
+    struct kvm_s390_mem_op mem_op = {
+        .sida_offset = offset,
+        .size = len,
+        .op = is_write ? KVM_S390_MEMOP_SIDA_WRITE
+                       : KVM_S390_MEMOP_SIDA_READ,
+        .buf = (uint64_t)hostbuf,
+    };
+    int ret;
+
+    if (!cap_mem_op || !cap_protected) {
+        return -ENOSYS;
+    }
+
+    ret = kvm_vcpu_ioctl(CPU(cpu), KVM_S390_MEM_OP, &mem_op);
+    if (ret < 0) {
+        error_report("KVM_S390_MEM_OP failed: %s", strerror(-ret));
+        abort();
+    }
+    return ret;
+}
+
 /*
  * Legacy layout for s390:
  * Older S390 KVM requires the topmost vma of the RAM to be

target/s390x/kvm_s390x.h

@@ -19,6 +19,8 @@ void kvm_s390_vcpu_interrupt(S390CPU *cpu, struct kvm_s390_irq *irq);
 void kvm_s390_access_exception(S390CPU *cpu, uint16_t code, uint64_t te_code);
 int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, uint8_t ar, void *hostbuf,
                     int len, bool is_write);
+int kvm_s390_mem_op_pv(S390CPU *cpu, vaddr addr, void *hostbuf, int len,
+                       bool is_write);
 void kvm_s390_program_interrupt(S390CPU *cpu, uint16_t code);
 int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state);
 void kvm_s390_vcpu_interrupt_pre_save(S390CPU *cpu);

target/s390x/mmu_helper.c

@@ -474,6 +474,20 @@ static int translate_pages(S390CPU *cpu, vaddr addr, int nr_pages,
     return 0;
 }
 
+int s390_cpu_pv_mem_rw(S390CPU *cpu, unsigned int offset, void *hostbuf,
+                       int len, bool is_write)
+{
+    int ret;
+
+    if (kvm_enabled()) {
+        ret = kvm_s390_mem_op_pv(cpu, offset, hostbuf, len, is_write);
+    } else {
+        /* Protected Virtualization is a KVM/Hardware only feature */
+        g_assert_not_reached();
+    }
+    return ret;
+}
+
 /**
  * s390_cpu_virt_mem_rw:
  * @laddr:     the logical start address