Re: [PATCH] hw/i386/intel_iommu: Simplify vtd_find_as_from_bus_num() logic

[Peter Xu]

On Wed, Feb 26, 2020 at 06:49:56PM +0100, Philippe Mathieu-Daudé wrote:
> Reorder the if() statement to simplify the function.
> This avoid bugs like the one fixed by commit a2e1cd41ccf.

This seems to hint that this patch fixes a problem, but it's pure
refactoring, right?

And I'm not sure about git-diff -w or so, but... I can't apply such a
patch cleanly using "git am".  Are you sure a patch like this would
work (without space change information)?

Thanks,

> 
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  hw/i386/intel_iommu.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 6258c58ac9..e720a8939c 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -987,14 +987,17 @@ static bool vtd_slpte_nonzero_rsvd(uint64_t slpte, 
> uint32_t level)
>  static VTDBus *vtd_find_as_from_bus_num(IntelIOMMUState *s, uint8_t bus_num)
>  {
>      VTDBus *vtd_bus = s->vtd_as_by_bus_num[bus_num];
> -    if (!vtd_bus) {
> +    GHashTableIter iter;
> +
> +    if (vtd_bus) {
> +        return vtd_bus;
> +    }
> +
>      /*
>       * Iterate over the registered buses to find the one which
>       * currently hold this bus number, and update the bus_num
>       * lookup table:
>       */
> -        GHashTableIter iter;
> -
>      g_hash_table_iter_init(&iter, s->vtd_as_by_busptr);
>      while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_bus)) {
>          if (pci_bus_num(vtd_bus->bus) == bus_num) {
> @@ -1002,9 +1005,8 @@ static VTDBus *vtd_find_as_from_bus_num(IntelIOMMUState 
> *s, uint8_t bus_num)
>              return vtd_bus;
>          }
>      }
> -        vtd_bus = NULL;
> -    }
> -    return vtd_bus;
> +
> +    return NULL;
>  }
>  
>  /* Given the @iova, get relevant @slptep. @slpte_level will be the last level
> -- 
> 2.21.1
> 

-- 
Peter Xu