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Re: [PATCH v1 15/36] target/riscv: Convert mstatus to pointers


From: Alistair Francis
Subject: Re: [PATCH v1 15/36] target/riscv: Convert mstatus to pointers
Date: Fri, 31 Jan 2020 16:09:06 -0800

On Fri, Jan 31, 2020 at 9:31 AM Alistair Francis <address@hidden> wrote:
>
> On Thu, Jan 30, 2020 at 6:48 AM Palmer Dabbelt <address@hidden> wrote:
> >
> > On Tue, 21 Jan 2020 11:02:01 GMT (+0000), address@hidden wrote:
> > > On Wed, Jan 8, 2020 at 11:30 AM Palmer Dabbelt <address@hidden> wrote:
> > >>
> > >> On Mon, 09 Dec 2019 10:11:19 PST (-0800), Alistair Francis wrote:
> > >> > To handle the new Hypervisor CSR register aliasing let's use pointers.
> > >>
> > >> For some reason I thought we were making this explicit?  In other words,
> > >> requiring that all callers provide which privilege mode they're using 
> > >> when
> > >> accessing these CSRs, as opposed to swapping around pointers.  I don't 
> > >> actually
> > >> care that much, but IIRC when we were talking with the ARM guys at 
> > >> Plumbers
> > >> they were pretty adament that would end up being a much cleaner 
> > >> implementation
> > >> as they'd tried this way and later changed over.
> > >
> > > I think their implementation is different so it doesn't apply the same 
> > > here.
> > >
> > > My main concern is that due to the modularity of RISC-V I don't expect
> > > all future developers to keep track of the Hypervisor extensions. This
> > > way we always have the correct state in the registers.
> > >
> > > There is only one pointer variable left, so we could drop the pointer
> > > swapping part, but for now it's still here.
> >
> > OK, so in the interest of moving things forwards let's just
> >
> > Reviewed-by: Palmer Dabbelt <address@hidden>
>
> Thanks
>
> >
> > so we can merge this -- it's too big of a patch set to wait around on 
> > something
> > so small for.  I think that was the last one missing a review, right?
>
> I have made one small change and dismissed your review from a patch,
> it also looks like one patch hasn't been reviewed either.
>
> I'll send a v2 later today that has been rebased on master.

After rebasing everything stopped working. While attempting to fix the
problem I remeoved this patch and managed to get it working again. So
now in v2 there are no CSR pointers, just value swapping for
everything.

I fixed a few bugs that I noticed related to FP, I have cleared your
review Palmer from a few patches. I'll send the v2 for review soon.
It's pretty similar to the v1 so should be easy to review.

Alistair

>
> Alistair
>
> >
> > >
> > > Alistair
> > >
> > >>
> > >> > Signed-off-by: Alistair Francis <address@hidden>
> > >> > ---
> > >> >  target/riscv/cpu.c        | 11 +++++++++--
> > >> >  target/riscv/cpu.h        |  9 ++++++++-
> > >> >  target/riscv/cpu_helper.c | 30 +++++++++++++++---------------
> > >> >  target/riscv/csr.c        | 20 ++++++++++----------
> > >> >  target/riscv/op_helper.c  | 14 +++++++-------
> > >> >  5 files changed, 49 insertions(+), 35 deletions(-)
> > >> >
> > >> > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> > >> > index a07c5689b3..e61cf46a73 100644
> > >> > --- a/target/riscv/cpu.c
> > >> > +++ b/target/riscv/cpu.c
> > >> > @@ -236,7 +236,7 @@ static void riscv_cpu_dump_state(CPUState *cs, 
> > >> > FILE *f, int flags)
> > >> >      qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "pc      ", env->pc);
> > >> >  #ifndef CONFIG_USER_ONLY
> > >> >      qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "mhartid ", 
> > >> > env->mhartid);
> > >> > -    qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "mstatus ", 
> > >> > env->mstatus);
> > >> > +    qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "mstatus ", 
> > >> > *env->mstatus);
> > >> >      if (riscv_has_ext(env, RVH)) {
> > >> >          qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "hstatus ", 
> > >> > env->hstatus);
> > >> >          qemu_fprintf(f, " %s " TARGET_FMT_lx "\n", "vsstatus ", 
> > >> > env->vsstatus);
> > >> > @@ -336,7 +336,7 @@ static void riscv_cpu_reset(CPUState *cs)
> > >> >      mcc->parent_reset(cs);
> > >> >  #ifndef CONFIG_USER_ONLY
> > >> >      env->priv = PRV_M;
> > >> > -    env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
> > >> > +    *env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
> > >> >      env->mcause = 0;
> > >> >      env->pc = env->resetvec;
> > >> >  #endif
> > >> > @@ -465,8 +465,15 @@ static void riscv_cpu_realize(DeviceState *dev, 
> > >> > Error **errp)
> > >> >  static void riscv_cpu_init(Object *obj)
> > >> >  {
> > >> >      RISCVCPU *cpu = RISCV_CPU(obj);
> > >> > +#ifndef CONFIG_USER_ONLY
> > >> > +    CPURISCVState *env = &cpu->env;
> > >> > +#endif
> > >> >
> > >> >      cpu_set_cpustate_pointers(cpu);
> > >> > +
> > >> > +#ifndef CONFIG_USER_ONLY
> > >> > +    env->mstatus = &env->mstatus_novirt;
> > >> > +#endif
> > >> >  }
> > >> >
> > >> >  static const VMStateDescription vmstate_riscv_cpu = {
> > >> > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> > >> > index 21ae5a8b19..9dc8303c62 100644
> > >> > --- a/target/riscv/cpu.h
> > >> > +++ b/target/riscv/cpu.h
> > >> > @@ -122,7 +122,7 @@ struct CPURISCVState {
> > >> >      target_ulong resetvec;
> > >> >
> > >> >      target_ulong mhartid;
> > >> > -    target_ulong mstatus;
> > >> > +    target_ulong *mstatus;
> > >> >
> > >> >      target_ulong mip;
> > >> >      uint32_t miclaim;
> > >> > @@ -145,6 +145,13 @@ struct CPURISCVState {
> > >> >      target_ulong mcause;
> > >> >      target_ulong mtval;  /* since: priv-1.10.0 */
> > >> >
> > >> > +    /* The following registers are the "real" versions that the 
> > >> > pointer
> > >> > +     * versions point to. These should never be used unless you know 
> > >> > what you
> > >> > +     * are doing. To access these use the pointer versions instead. 
> > >> > This is
> > >> > +     * required to handle the Hypervisor register swapping.
> > >> > +     */
> > >> > +    target_ulong mstatus_novirt;
> > >> > +
> > >> >      /* Hypervisor CSRs */
> > >> >      target_ulong hstatus;
> > >> >      target_ulong hedeleg;
> > >> > diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> > >> > index b00f66824a..9684da7f7d 100644
> > >> > --- a/target/riscv/cpu_helper.c
> > >> > +++ b/target/riscv/cpu_helper.c
> > >> > @@ -37,8 +37,8 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool 
> > >> > ifetch)
> > >> >  #ifndef CONFIG_USER_ONLY
> > >> >  static int riscv_cpu_local_irq_pending(CPURISCVState *env)
> > >> >  {
> > >> > -    target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
> > >> > -    target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
> > >> > +    target_ulong mstatus_mie = get_field(*env->mstatus, MSTATUS_MIE);
> > >> > +    target_ulong mstatus_sie = get_field(*env->mstatus, MSTATUS_SIE);
> > >> >      target_ulong pending = env->mip & env->mie;
> > >> >      target_ulong mie = env->priv < PRV_M || (env->priv == PRV_M && 
> > >> > mstatus_mie);
> > >> >      target_ulong sie = env->priv < PRV_S || (env->priv == PRV_S && 
> > >> > mstatus_sie);
> > >> > @@ -75,7 +75,7 @@ bool riscv_cpu_exec_interrupt(CPUState *cs, int 
> > >> > interrupt_request)
> > >> >  /* Return true is floating point support is currently enabled */
> > >> >  bool riscv_cpu_fp_enabled(CPURISCVState *env)
> > >> >  {
> > >> > -    if (env->mstatus & MSTATUS_FS) {
> > >> > +    if (*env->mstatus & MSTATUS_FS) {
> > >> >          return true;
> > >> >      }
> > >> >
> > >> > @@ -198,8 +198,8 @@ static int get_physical_address(CPURISCVState 
> > >> > *env, hwaddr *physical,
> > >> >      int mode = mmu_idx;
> > >> >
> > >> >      if (mode == PRV_M && access_type != MMU_INST_FETCH) {
> > >> > -        if (get_field(env->mstatus, MSTATUS_MPRV)) {
> > >> > -            mode = get_field(env->mstatus, MSTATUS_MPP);
> > >> > +        if (get_field(*env->mstatus, MSTATUS_MPRV)) {
> > >> > +            mode = get_field(*env->mstatus, MSTATUS_MPP);
> > >> >          }
> > >> >      }
> > >> >
> > >> > @@ -213,11 +213,11 @@ static int get_physical_address(CPURISCVState 
> > >> > *env, hwaddr *physical,
> > >> >
> > >> >      hwaddr base;
> > >> >      int levels, ptidxbits, ptesize, vm, sum;
> > >> > -    int mxr = get_field(env->mstatus, MSTATUS_MXR);
> > >> > +    int mxr = get_field(*env->mstatus, MSTATUS_MXR);
> > >> >
> > >> >      if (env->priv_ver >= PRIV_VERSION_1_10_0) {
> > >> >          base = (hwaddr)get_field(env->satp, SATP_PPN) << PGSHIFT;
> > >> > -        sum = get_field(env->mstatus, MSTATUS_SUM);
> > >> > +        sum = get_field(*env->mstatus, MSTATUS_SUM);
> > >> >          vm = get_field(env->satp, SATP_MODE);
> > >> >          switch (vm) {
> > >> >          case VM_1_10_SV32:
> > >> > @@ -237,8 +237,8 @@ static int get_physical_address(CPURISCVState 
> > >> > *env, hwaddr *physical,
> > >> >          }
> > >> >      } else {
> > >> >          base = (hwaddr)(env->sptbr) << PGSHIFT;
> > >> > -        sum = !get_field(env->mstatus, MSTATUS_PUM);
> > >> > -        vm = get_field(env->mstatus, MSTATUS_VM);
> > >> > +        sum = !get_field(*env->mstatus, MSTATUS_PUM);
> > >> > +        vm = get_field(*env->mstatus, MSTATUS_VM);
> > >> >          switch (vm) {
> > >> >          case VM_1_09_SV32:
> > >> >            levels = 2; ptidxbits = 10; ptesize = 4; break;
> > >> > @@ -492,8 +492,8 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr 
> > >> > address, int size,
> > >> >      ret = get_physical_address(env, &pa, &prot, address, access_type, 
> > >> > mmu_idx);
> > >> >
> > >> >      if (mode == PRV_M && access_type != MMU_INST_FETCH) {
> > >> > -        if (get_field(env->mstatus, MSTATUS_MPRV)) {
> > >> > -            mode = get_field(env->mstatus, MSTATUS_MPP);
> > >> > +        if (get_field(*env->mstatus, MSTATUS_MPRV)) {
> > >> > +            mode = get_field(*env->mstatus, MSTATUS_MPP);
> > >> >          }
> > >> >      }
> > >> >
> > >> > @@ -599,12 +599,12 @@ void riscv_cpu_do_interrupt(CPUState *cs)
> > >> >      if (env->priv <= PRV_S &&
> > >> >              cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
> > >> >          /* handle the trap in S-mode */
> > >> > -        target_ulong s = env->mstatus;
> > >> > +        target_ulong s = *env->mstatus;
> > >> >          s = set_field(s, MSTATUS_SPIE, env->priv_ver >= 
> > >> > PRIV_VERSION_1_10_0 ?
> > >> >              get_field(s, MSTATUS_SIE) : get_field(s, MSTATUS_UIE << 
> > >> > env->priv));
> > >> >          s = set_field(s, MSTATUS_SPP, env->priv);
> > >> >          s = set_field(s, MSTATUS_SIE, 0);
> > >> > -        env->mstatus = s;
> > >> > +        *env->mstatus = s;
> > >> >          env->scause = cause | ((target_ulong)async << 
> > >> > (TARGET_LONG_BITS - 1));
> > >> >          env->sepc = env->pc;
> > >> >          env->sbadaddr = tval;
> > >> > @@ -613,12 +613,12 @@ void riscv_cpu_do_interrupt(CPUState *cs)
> > >> >          riscv_cpu_set_mode(env, PRV_S);
> > >> >      } else {
> > >> >          /* handle the trap in M-mode */
> > >> > -        target_ulong s = env->mstatus;
> > >> > +        target_ulong s = *env->mstatus;
> > >> >          s = set_field(s, MSTATUS_MPIE, env->priv_ver >= 
> > >> > PRIV_VERSION_1_10_0 ?
> > >> >              get_field(s, MSTATUS_MIE) : get_field(s, MSTATUS_UIE << 
> > >> > env->priv));
> > >> >          s = set_field(s, MSTATUS_MPP, env->priv);
> > >> >          s = set_field(s, MSTATUS_MIE, 0);
> > >> > -        env->mstatus = s;
> > >> > +        *env->mstatus = s;
> > >> >          env->mcause = cause | ~(((target_ulong)-1) >> async);
> > >> >          env->mepc = env->pc;
> > >> >          env->mbadaddr = tval;
> > >> > diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> > >> > index 74e911af08..a4b598d49a 100644
> > >> > --- a/target/riscv/csr.c
> > >> > +++ b/target/riscv/csr.c
> > >> > @@ -136,7 +136,7 @@ static int write_fflags(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >      if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
> > >> >          return -1;
> > >> >      }
> > >> > -    env->mstatus |= MSTATUS_FS;
> > >> > +    *env->mstatus |= MSTATUS_FS;
> > >> >  #endif
> > >> >      riscv_cpu_set_fflags(env, val & (FSR_AEXC >> FSR_AEXC_SHIFT));
> > >> >      return 0;
> > >> > @@ -159,7 +159,7 @@ static int write_frm(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >      if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
> > >> >          return -1;
> > >> >      }
> > >> > -    env->mstatus |= MSTATUS_FS;
> > >> > +    *env->mstatus |= MSTATUS_FS;
> > >> >  #endif
> > >> >      env->frm = val & (FSR_RD >> FSR_RD_SHIFT);
> > >> >      return 0;
> > >> > @@ -183,7 +183,7 @@ static int write_fcsr(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >      if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
> > >> >          return -1;
> > >> >      }
> > >> > -    env->mstatus |= MSTATUS_FS;
> > >> > +    *env->mstatus |= MSTATUS_FS;
> > >> >  #endif
> > >> >      env->frm = (val & FSR_RD) >> FSR_RD_SHIFT;
> > >> >      riscv_cpu_set_fflags(env, (val & FSR_AEXC) >> FSR_AEXC_SHIFT);
> > >> > @@ -313,7 +313,7 @@ static int read_mhartid(CPURISCVState *env, int 
> > >> > csrno, target_ulong *val)
> > >> >  /* Machine Trap Setup */
> > >> >  static int read_mstatus(CPURISCVState *env, int csrno, target_ulong 
> > >> > *val)
> > >> >  {
> > >> > -    *val = env->mstatus;
> > >> > +    *val = *env->mstatus;
> > >> >      return 0;
> > >> >  }
> > >> >
> > >> > @@ -325,7 +325,7 @@ static int validate_vm(CPURISCVState *env, 
> > >> > target_ulong vm)
> > >> >
> > >> >  static int write_mstatus(CPURISCVState *env, int csrno, target_ulong 
> > >> > val)
> > >> >  {
> > >> > -    target_ulong mstatus = env->mstatus;
> > >> > +    target_ulong mstatus = *env->mstatus;
> > >> >      target_ulong mask = 0;
> > >> >      int dirty;
> > >> >
> > >> > @@ -365,7 +365,7 @@ static int write_mstatus(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >               ((mstatus & MSTATUS_FS) == MSTATUS_FS)) |
> > >> >              ((mstatus & MSTATUS_XS) == MSTATUS_XS);
> > >> >      mstatus = set_field(mstatus, MSTATUS_SD, dirty);
> > >> > -    env->mstatus = mstatus;
> > >> > +    *env->mstatus = mstatus;
> > >> >
> > >> >      return 0;
> > >> >  }
> > >> > @@ -614,7 +614,7 @@ static int read_sstatus(CPURISCVState *env, int 
> > >> > csrno, target_ulong *val)
> > >> >  {
> > >> >      target_ulong mask = ((env->priv_ver >= PRIV_VERSION_1_10_0) ?
> > >> >                           sstatus_v1_10_mask : sstatus_v1_9_mask);
> > >> > -    *val = env->mstatus & mask;
> > >> > +    *val = *env->mstatus & mask;
> > >> >      return 0;
> > >> >  }
> > >> >
> > >> > @@ -622,7 +622,7 @@ static int write_sstatus(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >  {
> > >> >      target_ulong mask = ((env->priv_ver >= PRIV_VERSION_1_10_0) ?
> > >> >                           sstatus_v1_10_mask : sstatus_v1_9_mask);
> > >> > -    target_ulong newval = (env->mstatus & ~mask) | (val & mask);
> > >> > +    target_ulong newval = (*env->mstatus & ~mask) | (val & mask);
> > >> >      return write_mstatus(env, CSR_MSTATUS, newval);
> > >> >  }
> > >> >
> > >> > @@ -737,7 +737,7 @@ static int read_satp(CPURISCVState *env, int 
> > >> > csrno, target_ulong *val)
> > >> >      if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
> > >> >          *val = 0;
> > >> >      } else if (env->priv_ver >= PRIV_VERSION_1_10_0) {
> > >> > -        if (env->priv == PRV_S && get_field(env->mstatus, 
> > >> > MSTATUS_TVM)) {
> > >> > +        if (env->priv == PRV_S && get_field(*env->mstatus, 
> > >> > MSTATUS_TVM)) {
> > >> >              return -1;
> > >> >          } else {
> > >> >              *val = env->satp;
> > >> > @@ -762,7 +762,7 @@ static int write_satp(CPURISCVState *env, int 
> > >> > csrno, target_ulong val)
> > >> >          validate_vm(env, get_field(val, SATP_MODE)) &&
> > >> >          ((val ^ env->satp) & (SATP_MODE | SATP_ASID | SATP_PPN)))
> > >> >      {
> > >> > -        if (env->priv == PRV_S && get_field(env->mstatus, 
> > >> > MSTATUS_TVM)) {
> > >> > +        if (env->priv == PRV_S && get_field(*env->mstatus, 
> > >> > MSTATUS_TVM)) {
> > >> >              return -1;
> > >> >          } else {
> > >> >              if((val ^ env->satp) & SATP_ASID) {
> > >> > diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
> > >> > index 331cc36232..d150551bc9 100644
> > >> > --- a/target/riscv/op_helper.c
> > >> > +++ b/target/riscv/op_helper.c
> > >> > @@ -83,11 +83,11 @@ target_ulong helper_sret(CPURISCVState *env, 
> > >> > target_ulong cpu_pc_deb)
> > >> >      }
> > >> >
> > >> >      if (env->priv_ver >= PRIV_VERSION_1_10_0 &&
> > >> > -        get_field(env->mstatus, MSTATUS_TSR)) {
> > >> > +        get_field(*env->mstatus, MSTATUS_TSR)) {
> > >> >          riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
> > >> >      }
> > >> >
> > >> > -    target_ulong mstatus = env->mstatus;
> > >> > +    target_ulong mstatus = *env->mstatus;
> > >> >      target_ulong prev_priv = get_field(mstatus, MSTATUS_SPP);
> > >> >      mstatus = set_field(mstatus,
> > >> >          env->priv_ver >= PRIV_VERSION_1_10_0 ?
> > >> > @@ -96,7 +96,7 @@ target_ulong helper_sret(CPURISCVState *env, 
> > >> > target_ulong cpu_pc_deb)
> > >> >      mstatus = set_field(mstatus, MSTATUS_SPIE, 0);
> > >> >      mstatus = set_field(mstatus, MSTATUS_SPP, PRV_U);
> > >> >      riscv_cpu_set_mode(env, prev_priv);
> > >> > -    env->mstatus = mstatus;
> > >> > +    *env->mstatus = mstatus;
> > >> >
> > >> >      return retpc;
> > >> >  }
> > >> > @@ -112,7 +112,7 @@ target_ulong helper_mret(CPURISCVState *env, 
> > >> > target_ulong cpu_pc_deb)
> > >> >          riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
> > >> >      }
> > >> >
> > >> > -    target_ulong mstatus = env->mstatus;
> > >> > +    target_ulong mstatus = *env->mstatus;
> > >> >      target_ulong prev_priv = get_field(mstatus, MSTATUS_MPP);
> > >> >      mstatus = set_field(mstatus,
> > >> >          env->priv_ver >= PRIV_VERSION_1_10_0 ?
> > >> > @@ -121,7 +121,7 @@ target_ulong helper_mret(CPURISCVState *env, 
> > >> > target_ulong cpu_pc_deb)
> > >> >      mstatus = set_field(mstatus, MSTATUS_MPIE, 0);
> > >> >      mstatus = set_field(mstatus, MSTATUS_MPP, PRV_U);
> > >> >      riscv_cpu_set_mode(env, prev_priv);
> > >> > -    env->mstatus = mstatus;
> > >> > +    *env->mstatus = mstatus;
> > >> >
> > >> >      return retpc;
> > >> >  }
> > >> > @@ -132,7 +132,7 @@ void helper_wfi(CPURISCVState *env)
> > >> >
> > >> >      if (env->priv == PRV_S &&
> > >> >          env->priv_ver >= PRIV_VERSION_1_10_0 &&
> > >> > -        get_field(env->mstatus, MSTATUS_TW)) {
> > >> > +        get_field(*env->mstatus, MSTATUS_TW)) {
> > >> >          riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
> > >> >      } else {
> > >> >          cs->halted = 1;
> > >> > @@ -147,7 +147,7 @@ void helper_tlb_flush(CPURISCVState *env)
> > >> >      if (!(env->priv >= PRV_S) ||
> > >> >          (env->priv == PRV_S &&
> > >> >           env->priv_ver >= PRIV_VERSION_1_10_0 &&
> > >> > -         get_field(env->mstatus, MSTATUS_TVM))) {
> > >> > +         get_field(*env->mstatus, MSTATUS_TVM))) {
> > >> >          riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
> > >> >      } else {
> > >> >          tlb_flush(cs);



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