Re: [PATCH 3/5] iommu/x86: use full addresses internally for the IVMD/RMRR range checks

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.02.2024 11:37, Roger Pau Monne wrote:
> Adjust the code in the checker to use full addresses rather than frame 
> numbers,
> as it's only page_get_ram_type() that requires an mfn parameter.
> 
> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

In this very shape I'd like to leave this to Paul or Andrew: I'm not outright
opposed, but I think this either goes too far (most type-safety being lost
again), or not far enough (both callers convert addresses to MFNs, just for
them to be converted back here).

Jan

> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -794,28 +794,26 @@ __initcall(adjust_irq_affinities);
>  
>  bool __init iommu_unity_region_ok(const char *prefix, mfn_t start, mfn_t end)
>  {
> -    mfn_t addr;
> +    paddr_t s = mfn_to_maddr(start), e = mfn_to_maddr(end);
>  
> -    if ( e820_all_mapped(mfn_to_maddr(start), mfn_to_maddr(end) + PAGE_SIZE,
> -                         E820_RESERVED) )
> +    if ( e820_all_mapped(s, e + PAGE_SIZE, E820_RESERVED) )
>          return true;
>  
>      printk(XENLOG_WARNING
>             "%s: [%#lx, %#lx] is not (entirely) in reserved memory\n",
> -           prefix, mfn_to_maddr(start), mfn_to_maddr(end));
> +           prefix, s, e);
>  
> -    for ( addr = start; mfn_x(addr) <= mfn_x(end); addr = mfn_add(addr, 1) )
> +    for ( paddr_t addr = s; addr <= e; addr += PAGE_SIZE )
>      {
> -        unsigned int type = page_get_ram_type(addr);
> +        unsigned int type = page_get_ram_type(maddr_to_mfn(addr));
>  
>          if ( type == RAM_TYPE_UNKNOWN )
>          {
> -            if ( e820_add_range(mfn_to_maddr(addr),
> -                                mfn_to_maddr(addr) + PAGE_SIZE, 
> E820_RESERVED) )
> +            if ( e820_add_range(addr, addr + PAGE_SIZE, E820_RESERVED) )
>                  continue;
>              printk(XENLOG_ERR
> -                   "%s: page at %#" PRI_mfn " couldn't be reserved\n",
> -                   prefix, mfn_x(addr));
> +                   "%s: page at %#lx couldn't be reserved\n",
> +                   prefix, paddr_to_pfn(addr));
>              return false;
>          }
>  
> @@ -829,9 +827,8 @@ bool __init iommu_unity_region_ok(const char *prefix, 
> mfn_t start, mfn_t end)
>                       RAM_TYPE_UNUSABLE) )
>              continue;
>  
> -        printk(XENLOG_ERR
> -               "%s: page at %#" PRI_mfn " can't be converted\n",
> -               prefix, mfn_x(addr));
> +        printk(XENLOG_ERR "%s: page at %#lx can't be converted\n",
> +               prefix, paddr_to_pfn(addr));
>          return false;
>      }
>