[PATCH v2] target/mips: Only update MVPControl.EVP bit if executed by master VPE

[Philippe Mathieu-Daudé]

According to the 'MIPS MT Application-Specific Extension' manual:

  If the VPE executing the instruction is not a Master VPE,
  with the MVP bit of the VPEConf0 register set, the EVP bit
  is unchanged by the instruction.

Modify the DVPE/EVPE opcodes to only update the MVPControl.EVP bit
if executed on a master VPE.

Reported-by: Hansni Bu <https://launchpad.net/%7Ehansni/+contactuser>
Buglink: https://bugs.launchpad.net/qemu/+bug/1926277
Fixes: f249412c749 ("mips: Add MT halting and waking of VPEs")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
Supersedes: <20210427103555.112652-1-f4bug@amsat.org>
v2: Check VPEConf0.MVP bit (hansni)
---
 target/mips/cp0_helper.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/target/mips/cp0_helper.c b/target/mips/cp0_helper.c
index aae2af6eccc..d5f274f5cdf 100644
--- a/target/mips/cp0_helper.c
+++ b/target/mips/cp0_helper.c
@@ -1635,12 +1635,14 @@ target_ulong helper_dvpe(CPUMIPSState *env)
     CPUState *other_cs = first_cpu;
     target_ulong prev = env->mvp->CP0_MVPControl;
 
-    CPU_FOREACH(other_cs) {
-        MIPSCPU *other_cpu = MIPS_CPU(other_cs);
-        /* Turn off all VPEs except the one executing the dvpe.  */
-        if (&other_cpu->env != env) {
-            other_cpu->env.mvp->CP0_MVPControl &= ~(1 << CP0MVPCo_EVP);
-            mips_vpe_sleep(other_cpu);
+    if (env->CP0_VPEConf0 & (1 << CP0VPEC0_MVP)) {
+        CPU_FOREACH(other_cs) {
+            MIPSCPU *other_cpu = MIPS_CPU(other_cs);
+            /* Turn off all VPEs except the one executing the dvpe.  */
+            if (&other_cpu->env != env) {
+                other_cpu->env.mvp->CP0_MVPControl &= ~(1 << CP0MVPCo_EVP);
+                mips_vpe_sleep(other_cpu);
+            }
         }
     }
     return prev;
@@ -1651,15 +1653,17 @@ target_ulong helper_evpe(CPUMIPSState *env)
     CPUState *other_cs = first_cpu;
     target_ulong prev = env->mvp->CP0_MVPControl;
 
-    CPU_FOREACH(other_cs) {
-        MIPSCPU *other_cpu = MIPS_CPU(other_cs);
+    if (env->CP0_VPEConf0 & (1 << CP0VPEC0_MVP)) {
+        CPU_FOREACH(other_cs) {
+            MIPSCPU *other_cpu = MIPS_CPU(other_cs);
 
-        if (&other_cpu->env != env
-            /* If the VPE is WFI, don't disturb its sleep.  */
-            && !mips_vpe_is_wfi(other_cpu)) {
-            /* Enable the VPE.  */
-            other_cpu->env.mvp->CP0_MVPControl |= (1 << CP0MVPCo_EVP);
-            mips_vpe_wake(other_cpu); /* And wake it up.  */
+            if (&other_cpu->env != env
+                /* If the VPE is WFI, don't disturb its sleep.  */
+                && !mips_vpe_is_wfi(other_cpu)) {
+                /* Enable the VPE.  */
+                other_cpu->env.mvp->CP0_MVPControl |= (1 << CP0MVPCo_EVP);
+                mips_vpe_wake(other_cpu); /* And wake it up.  */
+            }
         }
     }
     return prev;
-- 
2.26.3