Re: [PATCH v4 15/16] cputlb: Pass retaddr to tb_invalidate_phys_page_fast

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Rather than rely on cpu->mem_io_pc, pass retaddr down directly.
>
> Within tb_invalidate_phys_page_range__locked, the is_cpu_write_access
> parameter is non-zero exactly when retaddr would be non-zero, so that
> is a simple replacement.
>
> Recognize that current_tb_not_found is true only when mem_io_pc
> (and now retaddr) are also non-zero, so remove a redundant test.
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  accel/tcg/translate-all.h |  3 ++-
>  accel/tcg/cputlb.c        |  6 +-----
>  accel/tcg/translate-all.c | 39 +++++++++++++++++++--------------------
>  3 files changed, 22 insertions(+), 26 deletions(-)
>
> diff --git a/accel/tcg/translate-all.h b/accel/tcg/translate-all.h
> index 31f2117188..135c1ea96a 100644
> --- a/accel/tcg/translate-all.h
> +++ b/accel/tcg/translate-all.h
> @@ -27,7 +27,8 @@ struct page_collection *page_collection_lock(tb_page_addr_t start,
>                                               tb_page_addr_t end);
>  void page_collection_unlock(struct page_collection *set);
>  void tb_invalidate_phys_page_fast(struct page_collection *pages,
> -                                  tb_page_addr_t start, int len);
> +                                  tb_page_addr_t start, int len,
> +                                  uintptr_t retaddr);
>  void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end);
>  void tb_check_watchpoint(CPUState *cpu);
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 0ca6ee60b3..ea5d12c59d 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -1093,11 +1093,7 @@ static void notdirty_write(CPUState *cpu, vaddr mem_vaddr, unsigned size,
>      if (!cpu_physical_memory_get_dirty_flag(ram_addr, DIRTY_MEMORY_CODE)) {
>          struct page_collection *pages
>              = page_collection_lock(ram_addr, ram_addr + size);
> -
> -        /* We require mem_io_pc in tb_invalidate_phys_page_range.  */
> -        cpu->mem_io_pc = retaddr;
> -
> -        tb_invalidate_phys_page_fast(pages, ram_addr, size);
> +        tb_invalidate_phys_page_fast(pages, ram_addr, size, retaddr);
>          page_collection_unlock(pages);
>      }
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index de4b697163..db77fb221b 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -1889,7 +1889,7 @@ static void
>  tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>                                        PageDesc *p, tb_page_addr_t start,
>                                        tb_page_addr_t end,
> -                                      int is_cpu_write_access)
> +                                      uintptr_t retaddr)
>  {
>      TranslationBlock *tb;
>      tb_page_addr_t tb_start, tb_end;
> @@ -1897,9 +1897,9 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>  #ifdef TARGET_HAS_PRECISE_SMC
>      CPUState *cpu = current_cpu;
>      CPUArchState *env = NULL;
> -    int current_tb_not_found = is_cpu_write_access;
> +    bool current_tb_not_found = retaddr != 0;
> +    bool current_tb_modified = false;
>      TranslationBlock *current_tb = NULL;
> -    int current_tb_modified = 0;
>      target_ulong current_pc = 0;
>      target_ulong current_cs_base = 0;
>      uint32_t current_flags = 0;
> @@ -1931,24 +1931,21 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>          if (!(tb_end <= start || tb_start >= end)) {
>  #ifdef TARGET_HAS_PRECISE_SMC
>              if (current_tb_not_found) {
> -                current_tb_not_found = 0;
> -                current_tb = NULL;
> -                if (cpu->mem_io_pc) {
> -                    /* now we have a real cpu fault */
> -                    current_tb = tcg_tb_lookup(cpu->mem_io_pc);
> -                }
> +                current_tb_not_found = false;
> +                /* now we have a real cpu fault */
> +                current_tb = tcg_tb_lookup(retaddr);
>              }
>              if (current_tb == tb &&
>                  (tb_cflags(current_tb) & CF_COUNT_MASK) != 1) {
> -                /* If we are modifying the current TB, we must stop
> -                its execution. We could be more precise by checking
> -                that the modification is after the current PC, but it
> -                would require a specialized function to partially
> -                restore the CPU state */
> -
> -                current_tb_modified = 1;
> -                cpu_restore_state_from_tb(cpu, current_tb,
> -                                          cpu->mem_io_pc, true);
> +                /*
> +                 * If we are modifying the current TB, we must stop
> +                 * its execution. We could be more precise by checking
> +                 * that the modification is after the current PC, but it
> +                 * would require a specialized function to partially
> +                 * restore the CPU state.
> +                 */
> +                current_tb_modified = true;
> +                cpu_restore_state_from_tb(cpu, current_tb, retaddr, true);
>                  cpu_get_tb_cpu_state(env, &current_pc, &current_cs_base,
>                                       &current_flags);
>              }
> @@ -2042,7 +2039,8 @@ void tb_invalidate_phys_range(target_ulong start, target_ulong end)
>   * Call with all @pages in the range [@start, @start + len[ locked.
>   */
>  void tb_invalidate_phys_page_fast(struct page_collection *pages,
> -                                  tb_page_addr_t start, int len)
> +                                  tb_page_addr_t start, int len,
> +                                  uintptr_t retaddr)
>  {
>      PageDesc *p;
>
> @@ -2069,7 +2067,8 @@ void tb_invalidate_phys_page_fast(struct page_collection *pages,
>          }
>      } else {
>      do_invalidate:
> -        tb_invalidate_phys_page_range__locked(pages, p, start, start + len, 1);
> +        tb_invalidate_phys_page_range__locked(pages, p, start, start + len,
> +                                              retaddr);
>      }
>  }
>  #else


--
Alex Bennée