[RFC PATCH 29/35] target/arm: implements SEV/SEVL for all modes

Alex Bennée posted 35 patches 7 hours ago
Maintainers: Peter Maydell <peter.maydell@linaro.org>, Alexander Graf <agraf@csgraf.de>, Pedro Barbuda <pbarbuda@microsoft.com>, Mohamed Mediouni <mohamed@unpredictable.fr>
[RFC PATCH 29/35] target/arm: implements SEV/SEVL for all modes
Posted by Alex Bennée 7 hours ago
Remove the restrictions that make this a M-profile only operation and
enable the instructions for all Arm instructions.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 target/arm/tcg/a32.decode      |  5 ++---
 target/arm/tcg/a64.decode      |  5 ++---
 target/arm/tcg/t16.decode      |  4 +---
 target/arm/tcg/t32.decode      |  4 +---
 target/arm/tcg/op_helper.c     |  4 +---
 target/arm/tcg/translate-a64.c | 34 ++++++++++++++++++++++++++++++++++
 target/arm/tcg/translate.c     | 19 ++++++++++++++-----
 7 files changed, 55 insertions(+), 20 deletions(-)

diff --git a/target/arm/tcg/a32.decode b/target/arm/tcg/a32.decode
index f2ca4809495..d076681bf97 100644
--- a/target/arm/tcg/a32.decode
+++ b/target/arm/tcg/a32.decode
@@ -192,9 +192,8 @@ SMULTT           .... 0001 0110 .... 0000 .... 1110 ....      @rd0mn
       WFE        ---- 0011 0010 0000 1111 ---- 0000 0010
       WFI        ---- 0011 0010 0000 1111 ---- 0000 0011
 
-      # TODO: Implement SEV, SEVL; may help SMP performance.
-      # SEV      ---- 0011 0010 0000 1111 ---- 0000 0100
-      # SEVL     ---- 0011 0010 0000 1111 ---- 0000 0101
+      SEV      ---- 0011 0010 0000 1111 ---- 0000 0100
+      SEVL     ---- 0011 0010 0000 1111 ---- 0000 0101
 
       ESB        ---- 0011 0010 0000 1111 ---- 0001 0000
     ]
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
index 01b1b3e38be..dcb3099dd5c 100644
--- a/target/arm/tcg/a64.decode
+++ b/target/arm/tcg/a64.decode
@@ -237,9 +237,8 @@ ERETA           1101011 0100 11111 00001 m:1 11111 11111 &reta  # ERETAA, ERETAB
     YIELD       1101 0101 0000 0011 0010 0000 001 11111
     WFE         1101 0101 0000 0011 0010 0000 010 11111
     WFI         1101 0101 0000 0011 0010 0000 011 11111
-    # We implement WFE to never block, so our SEV/SEVL are NOPs
-    # SEV       1101 0101 0000 0011 0010 0000 100 11111
-    # SEVL      1101 0101 0000 0011 0010 0000 101 11111
+    SEV         1101 0101 0000 0011 0010 0000 100 11111
+    SEVL        1101 0101 0000 0011 0010 0000 101 11111
     # Our DGL is a NOP because we don't merge memory accesses anyway.
     # DGL       1101 0101 0000 0011 0010 0000 110 11111
     XPACLRI     1101 0101 0000 0011 0010 0000 111 11111
diff --git a/target/arm/tcg/t16.decode b/target/arm/tcg/t16.decode
index 778fbf16275..9a8f89538ac 100644
--- a/target/arm/tcg/t16.decode
+++ b/target/arm/tcg/t16.decode
@@ -228,10 +228,8 @@ REVSH           1011 1010 11 ... ...            @rdm
     WFE         1011 1111 0010 0000
     WFI         1011 1111 0011 0000
 
-    # M-profile SEV is implemented.
-    # TODO: Implement SEV for other profiles, and SEVL for all profiles; may help SMP performance.
     SEV         1011 1111 0100 0000
-    # SEVL      1011 1111 0101 0000
+    SEVL        1011 1111 0101 0000
 
     # The canonical nop has the second nibble as 0000, but the whole of the
     # rest of the space is a reserved hint, behaves as nop.
diff --git a/target/arm/tcg/t32.decode b/target/arm/tcg/t32.decode
index 49b8d0037ec..8ae277fe112 100644
--- a/target/arm/tcg/t32.decode
+++ b/target/arm/tcg/t32.decode
@@ -369,10 +369,8 @@ CLZ              1111 1010 1011 ---- 1111 .... 1000 ....      @rdm
         WFE      1111 0011 1010 1111 1000 0000 0000 0010
         WFI      1111 0011 1010 1111 1000 0000 0000 0011
 
-        # M-profile SEV is implemented.
-        # TODO: Implement SEV for other profiles, and SEVL for all profiles; may help SMP performance.
         SEV      1111 0011 1010 1111 1000 0000 0000 0100
-        # SEVL   1111 0011 1010 1111 1000 0000 0000 0101
+        SEVL     1111 0011 1010 1111 1000 0000 0000 0101
 
         ESB      1111 0011 1010 1111 1000 0000 0001 0000
       ]
diff --git a/target/arm/tcg/op_helper.c b/target/arm/tcg/op_helper.c
index b5c8024ace7..d513045269c 100644
--- a/target/arm/tcg/op_helper.c
+++ b/target/arm/tcg/op_helper.c
@@ -475,9 +475,7 @@ void HELPER(sev)(CPUARMState *env)
     CPUState *cs = env_cpu(env);
     CPU_FOREACH(cs) {
         ARMCPU *target_cpu = ARM_CPU(cs);
-        if (arm_feature(&target_cpu->env, ARM_FEATURE_M)) {
-            target_cpu->env.event_register.as_bool = true;
-        }
+        target_cpu->env.event_register.as_bool = true;
         if (!qemu_cpu_is_self(cs)) {
             qemu_cpu_kick(cs);
         }
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index d79c8ab431b..c25ff9351b4 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -562,6 +562,23 @@ static void gen_goto_tb(DisasContext *s, unsigned tb_slot_idx, int64_t diff)
     }
 }
 
+/*
+ * Event Register signalling.
+ *
+ * A bunch of activities trigger events, we just need to latch on to
+ * true. The event eventually gets consumed by WFE/WFET.
+ *
+ * user-mode treats these as nops.
+ */
+
+static void gen_event_reg(void)
+{
+#ifndef CONFIG_USER_ONLY
+    TCGv_i32 set_event = tcg_constant_i32(-1);
+    tcg_gen_st_i32(set_event, tcg_env, offsetof(CPUARMState, event_register));
+#endif
+}
+
 /*
  * Register access functions
  *
@@ -2032,6 +2049,23 @@ static bool trans_WFI(DisasContext *s, arg_WFI *a)
     return true;
 }
 
+static bool trans_SEV(DisasContext *s, arg_SEV *a)
+{
+    /*
+     * SEV is a NOP for user-mode emulation.
+     */
+#ifndef CONFIG_USER_ONLY
+    gen_helper_sev(tcg_env);
+#endif
+    return true;
+}
+
+static bool trans_SEVL(DisasContext *s, arg_SEV *a)
+{
+    gen_event_reg();
+    return true;
+}
+
 static bool trans_WFE(DisasContext *s, arg_WFI *a)
 {
     /*
diff --git a/target/arm/tcg/translate.c b/target/arm/tcg/translate.c
index f9d1b8897d2..3707561af0d 100644
--- a/target/arm/tcg/translate.c
+++ b/target/arm/tcg/translate.c
@@ -3244,13 +3244,22 @@ static bool trans_YIELD(DisasContext *s, arg_YIELD *a)
 static bool trans_SEV(DisasContext *s, arg_SEV *a)
 {
     /*
-     * Currently SEV is a NOP for non-M-profile and in user-mode emulation.
-     * For system-mode M-profile, it sets the event register.
+     * SEV is a NOP for user-mode emulation.
      */
 #ifndef CONFIG_USER_ONLY
-    if (arm_dc_feature(s, ARM_FEATURE_M)) {
-        gen_helper_sev(tcg_env);
-    }
+    gen_helper_sev(tcg_env);
+#endif
+    return true;
+}
+
+static bool trans_SEVL(DisasContext *s, arg_SEV *a)
+{
+    /*
+     * SEVL is a NOP for user-mode emulation.
+     */
+#ifndef CONFIG_USER_ONLY
+    TCGv_i32 set_event = tcg_constant_i32(-1);
+    tcg_gen_st_i32(set_event, tcg_env, offsetof(CPUARMState, event_register));
 #endif
     return true;
 }
-- 
2.47.3