Re: [PATCH v2 24/28] target/ppc/mmu_common.c: Remove BookE handling from get_physical_address_wtlb()

["Nicholas Piggin" <npiggin@gmail.com>]

On Wed May 8, 2024 at 9:40 AM AEST, BALATON Zoltan wrote:
> On Tue, 7 May 2024, Nicholas Piggin wrote:
> > On Thu May 2, 2024 at 9:43 AM AEST, BALATON Zoltan wrote:
> >> This function is no longer called for BookE MMU model so remove parts
> >> related to it. This has uncovered a few may be used uninitialised
> >> warnings that are also fixed.
> >>
> >> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> >> ---
> >>  target/ppc/mmu_common.c | 25 +++++--------------------
> >>  1 file changed, 5 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/target/ppc/mmu_common.c b/target/ppc/mmu_common.c
> >> index a1f98f8de4..d61c41d8c9 100644
> >> --- a/target/ppc/mmu_common.c
> >> +++ b/target/ppc/mmu_common.c
> >> @@ -684,12 +684,10 @@ static int mmubooke_get_physical_address(CPUPPCState *env, mmu_ctx_t *ctx,
> >>          ret = mmubooke_check_tlb(env, tlb, &raddr, &ctx->prot, address,
> >>                                   access_type, i);
> >>          if (ret != -1) {
> >> -            if (ret >= 0) {
> >> -                ctx->raddr = raddr;
> >> -            }
> >>              break;
> >>          }
> >>      }
> >> +    ctx->raddr = raddr;
> >>      qemu_log_mask(CPU_LOG_MMU,
> >>                    "%s: access %s " TARGET_FMT_lx " => " HWADDR_FMT_plx
> >>                    " %d %d\n", __func__, ret < 0 ? "refused" : "granted",
> >> @@ -897,9 +895,6 @@ static int mmubooke206_get_physical_address(CPUPPCState *env, mmu_ctx_t *ctx,
> >>              ret = mmubooke206_check_tlb(env, tlb, &raddr, &ctx->prot, address,
> >>                                          access_type, mmu_idx);
> >>              if (ret != -1) {
> >> -                if (ret >= 0) {
> >> -                    ctx->raddr = raddr;
> >> -                }
> >>                  goto found_tlb;
> >>              }
> >>          }
> >> @@ -907,6 +902,7 @@ static int mmubooke206_get_physical_address(CPUPPCState *env, mmu_ctx_t *ctx,
> >>
> >>  found_tlb:
> >>
> >> +    ctx->raddr = raddr;
> >
> > Not sure about the uninitialized warnings here either, caller probably
> > should not be using ctx->raddr unless we returned 0...
> >
> >>      qemu_log_mask(CPU_LOG_MMU, "%s: access %s " TARGET_FMT_lx " => "
> >>                    HWADDR_FMT_plx " %d %d\n", __func__,
> >>                    ret < 0 ? "refused" : "granted", address, raddr,
> >> @@ -1163,20 +1159,9 @@ static int get_physical_address_wtlb(CPUPPCState *env, mmu_ctx_t *ctx,
> >>                                       MMUAccessType access_type, int type,
> >>                                       int mmu_idx)
> >>  {
> >> -    bool real_mode;
> >> -
> >> -    if (env->mmu_model == POWERPC_MMU_BOOKE) {
> >> -        return mmubooke_get_physical_address(env, ctx, eaddr, access_type);
> >> -    } else if (env->mmu_model == POWERPC_MMU_BOOKE206) {
> >> -        return mmubooke206_get_physical_address(env, ctx, eaddr, access_type,
> >> -                                                mmu_idx);
> >> -    }
> >
> > This could just go in the previous patch when you split booke xlate?
>
> Removing this uncovers the warnings so I keep it here to separate it from 
> the previous change. I gave up on trying to resolve these warnings and 
> untangle the embedded functions from mmu_ctx_t which would be needed to 
> move these booke functions out from this file. The other problem is that 
> these booke get_physical_address functions and mmu40x_get_physical_address 
> all use ppcemb_tlb_check which then needs to be in the same file and 
> static to be inlined and not run too slow but 40x is still in jumbo_xlate 
> so I just leave it for now and may return to it later or let somebody else 
> continue from here. I think this series moves forward enough for now and I 
> don't have more time now.

If you can't easily drop the path or solve the problem okay, just put
a comment or something on the zeroing and I'll take a closer look
when I merge.

>
> >> -
> >> -    real_mode = (type == ACCESS_CODE) ? !FIELD_EX64(env->msr, MSR, IR)
> >> -                                      : !FIELD_EX64(env->msr, MSR, DR);
> >> -    if (real_mode && (env->mmu_model == POWERPC_MMU_SOFT_6xx ||
> >> -                      env->mmu_model == POWERPC_MMU_SOFT_4xx ||
> >> -                      env->mmu_model == POWERPC_MMU_REAL)) {
> >> +    bool real_mode = (type == ACCESS_CODE) ? !FIELD_EX64(env->msr, MSR, IR)
> >> +                                           : !FIELD_EX64(env->msr, MSR, DR);
> >> +    if (real_mode) {
> >>          memset(ctx, 0, sizeof(*ctx));
> >>          ctx->raddr = eaddr;
> >>          ctx->prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
> >
> > This still changes beahviour of MPC8xx MMU doesn't it? It's supposed
> > to abort always.
>
> I don't think it can get here because there's still an abort case in 
> ppc_tlb_invalidate_all() which is called from ppc_cpu_reset_hold() so it 
> will likely crash before it could call anything here. But if you think 
> it's necessary I could add a case for it in ppc_xlate() maybe.

I would rather not change it here. You can remove it with another patch.

Thanks,
Nick