[Qemu-devel] [PATCH 08/15] target-s390x: basic PER event handling

[Aurelien Jarno]

This patch add basic support to generate PER exceptions. It adds two
fields to the cpu structure to record for the PER address and PER
code & ATMID values. When an exception is triggered and a PER event is
pending, the two PER values are copied to the lowcore area.

At the end of an instruction, an helper is checking for a possible
pending PER event and triggers an exception in that case. For that to
work with branches, we need to disable TB chaining when PER is
activated. Fortunately it's already in the TB flags.

Finally in case of a SERVICE CALL exception, we need to trigger the PER
exception immediately after.

Cc: Alexander Graf <address@hidden>
Cc: Richard Henderson <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
 target-s390x/cpu.h         |  3 +++
 target-s390x/helper.c      | 54 ++++++++++++++++++++++++++++++----------------
 target-s390x/helper.h      |  1 +
 target-s390x/misc_helper.c | 15 +++++++++++++
 target-s390x/translate.c   | 18 +++++++++++++++-
 5 files changed, 71 insertions(+), 20 deletions(-)

diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index da60eba..19646b9 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -111,6 +111,9 @@ typedef struct CPUS390XState {
     uint32_t int_svc_code;
     uint32_t int_svc_ilen;
 
+    uint64_t per_address;
+    uint16_t per_perc_atmid;
+
     uint64_t cregs[16]; /* control registers */
 
     ExtQueue ext_queue[MAX_EXT_QUEUE];
diff --git a/target-s390x/helper.c b/target-s390x/helper.c
index 90d273c..ec847a2 100644
--- a/target-s390x/helper.c
+++ b/target-s390x/helper.c
@@ -250,25 +250,6 @@ void do_restart_interrupt(CPUS390XState *env)
     load_psw(env, mask, addr);
 }
 
-static void do_svc_interrupt(CPUS390XState *env)
-{
-    uint64_t mask, addr;
-    LowCore *lowcore;
-
-    lowcore = cpu_map_lowcore(env);
-
-    lowcore->svc_code = cpu_to_be16(env->int_svc_code);
-    lowcore->svc_ilen = cpu_to_be16(env->int_svc_ilen);
-    lowcore->svc_old_psw.mask = cpu_to_be64(get_psw_mask(env));
-    lowcore->svc_old_psw.addr = cpu_to_be64(env->psw.addr + env->int_svc_ilen);
-    mask = be64_to_cpu(lowcore->svc_new_psw.mask);
-    addr = be64_to_cpu(lowcore->svc_new_psw.addr);
-
-    cpu_unmap_lowcore(lowcore);
-
-    load_psw(env, mask, addr);
-}
-
 static void do_program_interrupt(CPUS390XState *env)
 {
     uint64_t mask, addr;
@@ -292,6 +273,14 @@ static void do_program_interrupt(CPUS390XState *env)
 
     lowcore = cpu_map_lowcore(env);
 
+    /* Signal PER events with the exception.  */
+    if (env->per_perc_atmid) {
+        env->int_pgm_code |= PGM_PER;
+        lowcore->per_address = cpu_to_be64(env->per_address);
+        lowcore->per_perc_atmid = cpu_to_be16(env->per_perc_atmid);
+        env->per_perc_atmid = 0;
+    }
+
     lowcore->pgm_ilen = cpu_to_be16(ilen);
     lowcore->pgm_code = cpu_to_be16(env->int_pgm_code);
     lowcore->program_old_psw.mask = cpu_to_be64(get_psw_mask(env));
@@ -308,6 +297,33 @@ static void do_program_interrupt(CPUS390XState *env)
     load_psw(env, mask, addr);
 }
 
+static void do_svc_interrupt(CPUS390XState *env)
+{
+    uint64_t mask, addr;
+    LowCore *lowcore;
+
+    lowcore = cpu_map_lowcore(env);
+
+    lowcore->svc_code = cpu_to_be16(env->int_svc_code);
+    lowcore->svc_ilen = cpu_to_be16(env->int_svc_ilen);
+    lowcore->svc_old_psw.mask = cpu_to_be64(get_psw_mask(env));
+    lowcore->svc_old_psw.addr = cpu_to_be64(env->psw.addr + env->int_svc_ilen);
+    mask = be64_to_cpu(lowcore->svc_new_psw.mask);
+    addr = be64_to_cpu(lowcore->svc_new_psw.addr);
+
+    cpu_unmap_lowcore(lowcore);
+
+    load_psw(env, mask, addr);
+
+    /* When a PER event is pending, the PER exception has to happen
+       immediately after the SERVICE CALL one.  */
+    if (env->per_perc_atmid) {
+        env->int_pgm_code = PGM_PER;
+        env->int_pgm_ilen = env->int_svc_ilen;
+        do_program_interrupt(env);
+    }
+}
+
 #define VIRTIO_SUBCODE_64 0x0D00
 
 static void do_ext_interrupt(CPUS390XState *env)
diff --git a/target-s390x/helper.h b/target-s390x/helper.h
index 7e048ec..37bd4d7 100644
--- a/target-s390x/helper.h
+++ b/target-s390x/helper.h
@@ -116,4 +116,5 @@ DEF_HELPER_FLAGS_2(lura, TCG_CALL_NO_WG, i64, env, i64)
 DEF_HELPER_FLAGS_2(lurag, TCG_CALL_NO_WG, i64, env, i64)
 DEF_HELPER_FLAGS_3(stura, TCG_CALL_NO_WG, void, env, i64, i64)
 DEF_HELPER_FLAGS_3(sturg, TCG_CALL_NO_WG, void, env, i64, i64)
+DEF_HELPER_1(per_check_exception, void, env)
 #endif
diff --git a/target-s390x/misc_helper.c b/target-s390x/misc_helper.c
index b375ab7..d19ae91 100644
--- a/target-s390x/misc_helper.c
+++ b/target-s390x/misc_helper.c
@@ -494,3 +494,18 @@ uint32_t HELPER(sigp)(CPUS390XState *env, uint64_t 
order_code, uint32_t r1,
     return cc;
 }
 #endif
+
+#ifndef CONFIG_USER_ONLY
+void HELPER(per_check_exception)(CPUS390XState *env)
+{
+    CPUState *cs = CPU(s390_env_get_cpu(env));
+
+    if (env->per_perc_atmid) {
+        env->int_pgm_code = PGM_PER;
+        env->int_pgm_ilen = get_ilen(cpu_ldub_code(env, env->per_address));
+
+        cs->exception_index = EXCP_PGM;
+        cpu_loop_exit(cs);
+    }
+}
+#endif
diff --git a/target-s390x/translate.c b/target-s390x/translate.c
index 9b87714..ff2c4bb 100644
--- a/target-s390x/translate.c
+++ b/target-s390x/translate.c
@@ -568,7 +568,8 @@ static int use_goto_tb(DisasContext *s, uint64_t dest)
     return (((dest & TARGET_PAGE_MASK) == (s->tb->pc & TARGET_PAGE_MASK)
              || (dest & TARGET_PAGE_MASK) == ((s->pc - 1) & TARGET_PAGE_MASK))
             && !s->singlestep_enabled
-            && !(s->tb->cflags & CF_LAST_IO));
+            && !(s->tb->cflags & CF_LAST_IO)
+            && !(s->tb->flags & FLAG_MASK_PER));
 }
 
 static void account_noninline_branch(DisasContext *s, int cc_op)
@@ -5138,6 +5139,21 @@ static ExitStatus translate_one(CPUS390XState *env, 
DisasContext *s)
         tcg_temp_free_i64(o.addr1);
     }
 
+#ifndef CONFIG_USER_ONLY
+    if (s->tb->flags & FLAG_MASK_PER) {
+        /* An exception might be triggered, save PSW if not already done.  */
+        if (ret == NO_EXIT || ret == EXIT_PC_STALE) {
+            tcg_gen_movi_i64(psw_addr, s->next_pc);
+        }
+
+        /* Save off cc.  */
+        update_cc_op(s);
+
+        /* Call the helper to check for a possible PER exception.  */
+        gen_helper_per_check_exception(cpu_env);
+    }
+#endif
+
     /* Advance to the next instruction.  */
     s->pc = s->next_pc;
     return ret;
-- 
2.1.4