[Bug 1926277] Re: MIPS MT dvpe does not regard VPEConf0.MVP

[Hansni Bu]

Hi Philippe,

Instead of checking with MVPConf0, I think we should check with
VPEConf0.

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https://bugs.launchpad.net/bugs/1926277

Title:
  MIPS MT dvpe does not regard VPEConf0.MVP

Status in QEMU:
  Confirmed

Bug description:
  Hi,

  According to MIPS32® Architecture for Programmers VolumeIV-f: The
  MIPS® MT Application-Specific Extension to the MIPS32® Architecture,
  for instruction: dvpe, evpe:

  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.

  The pseudo code is:

  data ←  MVPControl
  GPR[rt] ←  data
  if(VPEConf0.MVP = 1) then
    MVPControl.EVP ←  sc
  endif

  However the helper functions of dvpe, evpe does not regard the
  VPEConf0.MVP bit, namely, it does not check if the VPE is a master
  VPE. Code is copied below as:

  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);
          }
      }
      return prev;
  }

  Is this a bug?

  QEMU head commit: 0cef06d18762374c94eb4d511717a4735d668a24 is checked.

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