[PATCH v6 05/18] s390x: protvirt: Handle diag 308 subcodes 0,1,3,4

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

As we now have access to the protection state of the cpus, we can
implement special handling of diag 308 subcodes for cpus in the
protected state.

For subcodes 0 and 1 we need to unshare all pages before continuing,
so the guest doesn't accidentally expose data when dumping.

For subcode 3/4 we tear down the protected VM and reboot into
unprotected mode. We do not provide a secure reboot.

Before we can do the unshare calls, we need to mark all cpus as
stopped.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 hw/s390x/s390-virtio-ccw.c | 36 +++++++++++++++++++++++++++++++++---
 target/s390x/diag.c        |  4 ++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 272531a9ee..038bad54cd 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -397,12 +397,27 @@ static void s390_machine_inject_pv_error(CPUState *cs)
     env->regs[r1 + 1] = DIAG_308_RC_INVAL_FOR_PV;
 }
 
+static void s390_pv_prepare_reset(CPUS390XState *env)
+{
+    CPUState *cs;
+
+    if (!env->pv) {
+        return;
+    }
+    CPU_FOREACH(cs) {
+        s390_cpu_set_state(S390_CPU_STATE_STOPPED, S390_CPU(cs));
+    }
+    s390_pv_unshare();
+    s390_pv_perf_clear_reset();
+}
+
 static void s390_machine_reset(MachineState *machine)
 {
     enum s390_reset reset_type;
     CPUState *cs, *t;
     S390CPU *cpu;
     S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
+    CPUS390XState *env;
 
     /* get the reset parameters, reset them once done */
     s390_ipl_get_reset_request(&cs, &reset_type);
@@ -411,10 +426,15 @@ static void s390_machine_reset(MachineState *machine)
     s390_cmma_reset();
 
     cpu = S390_CPU(cs);
+    env = &cpu->env;
 
     switch (reset_type) {
     case S390_RESET_EXTERNAL:
     case S390_RESET_REIPL:
+        if (ms->pv) {
+            s390_machine_unprotect(ms);
+        }
+
         qemu_devices_reset();
         s390_crypto_reset();
 
@@ -422,21 +442,31 @@ static void s390_machine_reset(MachineState *machine)
         run_on_cpu(cs, s390_do_cpu_ipl, RUN_ON_CPU_NULL);
         break;
     case S390_RESET_MODIFIED_CLEAR:
+        /*
+         * Susbsystem reset needs to be done before we unshare memory
+         * and loose access to VIRTIO structures in guest memory.
+         */
+        subsystem_reset();
+        s390_crypto_reset();
+        s390_pv_prepare_reset(env);
         CPU_FOREACH(t) {
             run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
         }
-        subsystem_reset();
-        s390_crypto_reset();
         run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
         break;
     case S390_RESET_LOAD_NORMAL:
+        /*
+         * Susbsystem reset needs to be done before we unshare memory
+         * and loose access to VIRTIO structures in guest memory.
+         */
+        subsystem_reset();
+        s390_pv_prepare_reset(env);
         CPU_FOREACH(t) {
             if (t == cs) {
                 continue;
             }
             run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL);
         }
-        subsystem_reset();
         run_on_cpu(cs, s390_do_cpu_initial_reset, RUN_ON_CPU_NULL);
         run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
         break;
diff --git a/target/s390x/diag.c b/target/s390x/diag.c
index 945b263f0a..a6cd1ea260 100644
--- a/target/s390x/diag.c
+++ b/target/s390x/diag.c
@@ -67,6 +67,10 @@ int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3)
 static int diag308_parm_check(CPUS390XState *env, uint64_t r1, uint64_t addr,
                               uintptr_t ra, bool write)
 {
+    /* Handled by the Ultravisor */
+    if (env->pv) {
+        return 0;
+    }
     if ((r1 & 1) || (addr & ~TARGET_PAGE_MASK)) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return -1;
-- 
2.20.1