Re: [PATCH v2 2/2] target/m68k: consolidate physical translation offset into get_physical_address()

From: Laurent Vivier <laurent@vivier.eu>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, qemu-devel@nongnu.org
Subject: Re: [PATCH v2 2/2] target/m68k: consolidate physical translation offset into get_physical_address()
Date: Tue, 30 Jun 2020 09:23:00 +0200	[thread overview]
Message-ID: <747ff000-aa47-5f9d-a953-0c503c6be78a@vivier.eu> (raw)
In-Reply-To: <20200630061036.7526-3-mark.cave-ayland@ilande.co.uk>

Le 30/06/2020 à 08:10, Mark Cave-Ayland a écrit :
> Since all callers to get_physical_address() now apply the same page offset to
> the translation result, move the logic into get_physical_address() itself to
> avoid duplication.
> 
> Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
>  target/m68k/helper.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/target/m68k/helper.c b/target/m68k/helper.c
> index 631eab7774..ddd8a2667e 100644
> --- a/target/m68k/helper.c
> +++ b/target/m68k/helper.c
> @@ -771,7 +771,8 @@ static int get_physical_address(CPUM68KState *env, hwaddr *physical,
>      }
>      *page_size = 1 << page_bits;
>      page_mask = ~(*page_size - 1);
> -    *physical = next & page_mask;
> +    address &= TARGET_PAGE_MASK;
> +    *physical = (next & page_mask) + (address & (*page_size - 1));

You didn't update the Transparent Translation Register part.

>  
>      if (access_type & ACCESS_PTEST) {
>          env->mmu.mmusr |= next & M68K_MMU_SR_MASK_040;
> @@ -826,8 +827,6 @@ hwaddr m68k_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
>          return -1;
>      }
>  
> -    addr &= TARGET_PAGE_MASK;
> -    phys_addr += addr & (page_size - 1);
>      return phys_addr;
>  }
>  
> @@ -891,10 +890,7 @@ bool m68k_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>      ret = get_physical_address(&cpu->env, &physical, &prot,
>                                 address, access_type, &page_size);
>      if (likely(ret == 0)) {
> -        address &= TARGET_PAGE_MASK;
> -        physical += address & (page_size - 1);
> -        tlb_set_page(cs, address, physical,
> -                     prot, mmu_idx, TARGET_PAGE_SIZE);
> +        tlb_set_page(cs, address, physical, prot, mmu_idx, page_size);

but now we use "address" which is not the exact virtual address but the
virtual address of the page. According to the name, tlb_set_page(), and
the other users in QEMU, it should be:

 tlb_set_page(cs, address & TARGET_PAGE_MASK,
                  physical & TARGET_PAGE_MASK, prot, mmu_idx,
                  page_size);

Thanks,
Laurent