Re: [Qemu-arm] [PATCH 1/6] accel/tcg: Pass read access type through to io_readx()

[Philippe Mathieu-Daudé]

On 07/10/2018 01:00 PM, Peter Maydell wrote:
> The io_readx() function needs to know whether the load it is
> doing is an MMU_DATA_LOAD or an MMU_INST_FETCH, so that it
> can pass the right value to the cpu_transaction_failed()
> function. Plumb this information through from the softmmu
> code.
> 
> This is currently not often going to give the wrong answer,
> because usually instruction fetches go via get_page_addr_code().
> However once we switch over to handling execution from non-RAM by
> creating single-insn TBs, the path for an insn fetch to generate
> a bus error will be through cpu_ld*_code() and io_readx(),
> so without this change we will generate a d-side fault when we
> should generate an i-side fault.
> 
> We also have to pass the access type via a CPU struct global
> down to unassigned_mem_read(), for the benefit of the targets
> which still use the cpu_unassigned_access() hook (m68k, mips,
> sparc, xtensa).
> 
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>  accel/tcg/softmmu_template.h | 11 +++++++----
>  include/qom/cpu.h            |  6 ++++++
>  accel/tcg/cputlb.c           |  5 +++--
>  memory.c                     |  3 ++-
>  4 files changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/accel/tcg/softmmu_template.h b/accel/tcg/softmmu_template.h
> index badbf148803..f060a693d41 100644
> --- a/accel/tcg/softmmu_template.h
> +++ b/accel/tcg/softmmu_template.h
> @@ -99,11 +99,12 @@ static inline DATA_TYPE glue(io_read, 
> SUFFIX)(CPUArchState *env,
>                                                size_t mmu_idx, size_t index,
>                                                target_ulong addr,
>                                                uintptr_t retaddr,
> -                                              bool recheck)
> +                                              bool recheck,
> +                                              MMUAccessType access_type)
>  {
>      CPUIOTLBEntry *iotlbentry = &env->iotlb[mmu_idx][index];
>      return io_readx(env, iotlbentry, mmu_idx, addr, retaddr, recheck,
> -                    DATA_SIZE);
> +                    access_type, DATA_SIZE);
>  }
>  #endif
>  
> @@ -140,7 +141,8 @@ WORD_TYPE helper_le_ld_name(CPUArchState *env, 
> target_ulong addr,
>          /* ??? Note that the io helpers always read data in the target
>             byte ordering.  We should push the LE/BE request down into io.  */
>          res = glue(io_read, SUFFIX)(env, mmu_idx, index, addr, retaddr,
> -                                    tlb_addr & TLB_RECHECK);
> +                                    tlb_addr & TLB_RECHECK,
> +                                    READ_ACCESS_TYPE);
>          res = TGT_LE(res);
>          return res;
>      }
> @@ -207,7 +209,8 @@ WORD_TYPE helper_be_ld_name(CPUArchState *env, 
> target_ulong addr,
>          /* ??? Note that the io helpers always read data in the target
>             byte ordering.  We should push the LE/BE request down into io.  */
>          res = glue(io_read, SUFFIX)(env, mmu_idx, index, addr, retaddr,
> -                                    tlb_addr & TLB_RECHECK);
> +                                    tlb_addr & TLB_RECHECK,
> +                                    READ_ACCESS_TYPE);
>          res = TGT_BE(res);
>          return res;
>      }
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index bd796579ee4..ecf6ed556a9 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -386,6 +386,12 @@ struct CPUState {
>       */
>      uintptr_t mem_io_pc;
>      vaddr mem_io_vaddr;
> +    /*
> +     * This is only needed for the legacy cpu_unassigned_access() hook;
> +     * when all targets using it have been converted to use
> +     * cpu_transaction_failed() instead it can be removed.
> +     */
> +    MMUAccessType mem_io_access_type;
>  
>      int kvm_fd;
>      struct KVMState *kvm_state;
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 20c147d6554..c491703f15f 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -789,7 +789,7 @@ static inline ram_addr_t 
> qemu_ram_addr_from_host_nofail(void *ptr)
>  static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
>                           int mmu_idx,
>                           target_ulong addr, uintptr_t retaddr,
> -                         bool recheck, int size)
> +                         bool recheck, MMUAccessType access_type, int size)
>  {
>      CPUState *cpu = ENV_GET_CPU(env);
>      hwaddr mr_offset;
> @@ -831,6 +831,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry 
> *iotlbentry,
>      }
>  
>      cpu->mem_io_vaddr = addr;
> +    cpu->mem_io_access_type = access_type;
>  
>      if (mr->global_locking && !qemu_mutex_iothread_locked()) {
>          qemu_mutex_lock_iothread();
> @@ -843,7 +844,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry 
> *iotlbentry,
>              section->offset_within_address_space -
>              section->offset_within_region;
>  
> -        cpu_transaction_failed(cpu, physaddr, addr, size, MMU_DATA_LOAD,
> +        cpu_transaction_failed(cpu, physaddr, addr, size, access_type,
>                                 mmu_idx, iotlbentry->attrs, r, retaddr);
>      }
>      if (locked) {
> diff --git a/memory.c b/memory.c
> index e9cd4469688..2ea16e7bfb0 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1249,7 +1249,8 @@ static uint64_t unassigned_mem_read(void *opaque, 
> hwaddr addr,
>      printf("Unassigned mem read " TARGET_FMT_plx "\n", addr);
>  #endif
>      if (current_cpu != NULL) {
> -        cpu_unassigned_access(current_cpu, addr, false, false, 0, size);
> +        bool is_exec = current_cpu->mem_io_access_type == MMU_INST_FETCH;
> +        cpu_unassigned_access(current_cpu, addr, false, is_exec, 0, size);
>      }
>      return 0;
>  }
>