s390x: handle exceptions during s390_cpu_virt_mem_rw() correctly (TCG)

s390_cpu_virt_mem_rw() must always return, so callers can react on
an exception (e.g. see ioinst_handle_stcrw()).

However, for TCG we always have to exit the cpu loop (and restore the
cpu state before that) if we injected a program interrupt. So let's
introduce and use s390_cpu_virt_mem_handle_exc() in code that is not
purely KVM.

Directly pass the retaddr we already have available in these functions.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20171130162744.25442-8-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

hw/s390x/s390-pci-inst.c

@@ -163,6 +163,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t ra)
     }
 
     if (s390_cpu_virt_mem_read(cpu, env->regs[r2], r2, buffer, sizeof(*reqh))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
     reqh = (ClpReqHdr *)buffer;
@@ -174,6 +175,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t ra)
 
     if (s390_cpu_virt_mem_read(cpu, env->regs[r2], r2, buffer,
                                req_len + sizeof(*resh))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
     resh = (ClpRspHdr *)(buffer + req_len);
@@ -189,6 +191,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t ra)
 
     if (s390_cpu_virt_mem_read(cpu, env->regs[r2], r2, buffer,
                                req_len + res_len)) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
 
@@ -308,6 +311,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t ra)
 out:
     if (s390_cpu_virt_mem_write(cpu, env->regs[r2], r2, buffer,
                                 req_len + res_len)) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
     setcc(cpu, cc);
@@ -692,6 +696,7 @@ int pcistb_service_call(S390CPU *cpu, uint8_t r1, uint8_t r3, uint64_t gaddr,
     }
 
     if (s390_cpu_virt_mem_read(cpu, gaddr, ar, buffer, len)) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
 
@@ -848,6 +853,7 @@ int mpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar,
     }
 
     if (s390_cpu_virt_mem_read(cpu, fiba, ar, (uint8_t *)&fib, sizeof(fib))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
 
@@ -1029,6 +1035,7 @@ int stpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar,
 
 out:
     if (s390_cpu_virt_mem_write(cpu, fiba, ar, (uint8_t *)&fib, sizeof(fib))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return 0;
     }
 

target/s390x/cpu.h

@@ -736,6 +736,7 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, uint8_t ar, void *hostbuf,
         s390_cpu_virt_mem_rw(cpu, laddr, ar, dest, len, true)
 #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);
 
 
 /* sigp.c */

target/s390x/ioinst.c

@@ -120,6 +120,7 @@ void ioinst_handle_msch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
         return;
     }
     if (s390_cpu_virt_mem_read(cpu, addr, ar, &schib, sizeof(schib))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return;
     }
     if (ioinst_disassemble_sch_ident(reg1, &m, &cssid, &ssid, &schid) ||
@@ -176,6 +177,7 @@ void ioinst_handle_ssch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
         return;
     }
     if (s390_cpu_virt_mem_read(cpu, addr, ar, &orig_orb, sizeof(orb))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return;
     }
     copy_orb_from_guest(&orb, &orig_orb);
@@ -212,9 +214,12 @@ void ioinst_handle_stcrw(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
 
     if (s390_cpu_virt_mem_write(cpu, addr, ar, &crw, sizeof(crw)) == 0) {
         setcc(cpu, cc);
-    } else if (cc == 0) {
-        /* Write failed: requeue CRW since STCRW is a suppressing instruction */
-        css_undo_stcrw(&crw);
+    } else {
+        if (cc == 0) {
+            /* Write failed: requeue CRW since STCRW is suppressing */
+            css_undo_stcrw(&crw);
+        }
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
     }
 }
 
@@ -243,6 +248,8 @@ void ioinst_handle_stsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb,
          */
         if (!s390_cpu_virt_mem_check_write(cpu, addr, ar, sizeof(schib))) {
             s390_program_interrupt(env, PGM_OPERAND, 4, ra);
+        } else {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
         }
         return;
     }
@@ -268,11 +275,13 @@ void ioinst_handle_stsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb,
     if (cc != 3) {
         if (s390_cpu_virt_mem_write(cpu, addr, ar, &schib,
                                     sizeof(schib)) != 0) {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
             return;
         }
     } else {
         /* Access exceptions have a higher priority than cc3 */
         if (s390_cpu_virt_mem_check_write(cpu, addr, ar, sizeof(schib)) != 0) {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
             return;
         }
     }
@@ -309,6 +318,7 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
     /* 0 - status pending, 1 - not status pending, 3 - not operational */
     if (cc != 3) {
         if (s390_cpu_virt_mem_write(cpu, addr, ar, &irb, irb_len) != 0) {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
             return -EFAULT;
         }
         css_do_tsch_update_subch(sch);
@@ -316,6 +326,7 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
         irb_len = sizeof(irb) - sizeof(irb.emw);
         /* Access exceptions have a higher priority than cc3 */
         if (s390_cpu_virt_mem_check_write(cpu, addr, ar, irb_len) != 0) {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
             return -EFAULT;
         }
     }
@@ -611,6 +622,7 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
      * care of req->len here first.
      */
     if (s390_cpu_virt_mem_read(cpu, addr, reg, buf, sizeof(ChscReq))) {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
         return;
     }
     req = (ChscReq *)buf;
@@ -645,6 +657,8 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
     if (!s390_cpu_virt_mem_write(cpu, addr + len, reg, res,
                                  be16_to_cpu(res->len))) {
         setcc(cpu, 0);    /* Command execution complete */
+    } else {
+        s390_cpu_virt_mem_handle_exc(cpu, ra);
     }
 }
 

target/s390x/mmu_helper.c

@@ -22,6 +22,7 @@
 #include "internal.h"
 #include "kvm_s390x.h"
 #include "sysemu/kvm.h"
+#include "exec/exec-all.h"
 #include "trace.h"
 #include "hw/s390x/storage-keys.h"
 
@@ -478,6 +479,9 @@ static int translate_pages(S390CPU *cpu, vaddr addr, int nr_pages,
  *
  * Copy from/to guest memory using logical addresses. Note that we inject a
  * program interrupt in case there is an error while accessing the memory.
+ *
+ * This function will always return (also for TCG), make sure to call
+ * s390_cpu_virt_mem_handle_exc() to properly exit the CPU loop.
  */
 int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, uint8_t ar, void *hostbuf,
                          int len, bool is_write)
@@ -514,6 +518,16 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, uint8_t ar, void *hostbuf,
     return ret;
 }
 
+void s390_cpu_virt_mem_handle_exc(S390CPU *cpu, uintptr_t ra)
+{
+    /* KVM will handle the interrupt automatically, TCG has to exit the TB */
+#ifdef CONFIG_TCG
+    if (tcg_enabled()) {
+        cpu_loop_exit_restore(CPU(cpu), ra);
+    }
+#endif
+}
+
 /**
  * Translate a real address into a physical (absolute) address.
  * @param raddr  the real address