Re: [Xen-devel] [PATCH 2/2] x86/HVM: fix forwarding of internally cached requests (part 2)

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 28 April 2016 10:33
> To: xen-devel
> Cc: Paul Durrant; Wei Liu
> Subject: [PATCH 2/2] x86/HVM: fix forwarding of internally cached requests
> (part 2)
> 
> Commit 96ae556569 ("x86/HVM: fix forwarding of internally cached
> requests") wasn't quite complete: hvmemul_do_io() also needs to
> propagate up the clipped count. (I really should have re-tested the
> forward port resulting in the earlier change, instead of relying on the
> testing done on the older version of Xen which the fix was first needed
> for.)
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> 
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -137,7 +137,7 @@ static int hvmemul_do_io(
>          if ( (p.type != (is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO)) ||
>               (p.addr != addr) ||
>               (p.size != size) ||
> -             (p.count != *reps) ||
> +             (p.count > *reps) ||
>               (p.dir != dir) ||
>               (p.df != df) ||
>               (p.data_is_ptr != data_is_addr) )
> @@ -145,6 +145,8 @@ static int hvmemul_do_io(
> 
>          if ( data_is_addr )
>              return X86EMUL_UNHANDLEABLE;
> +
> +        *reps = p.count;
>          goto finish_access;
>      default:
>          return X86EMUL_UNHANDLEABLE;
> @@ -162,6 +164,13 @@ static int hvmemul_do_io(
> 
>      rc = hvm_io_intercept(&p);
> 
> +    /*
> +     * p.count may have got reduced (see hvm_process_io_intercept()) -
> inform
> +     * our callers and mirror this into latched state.
> +     */
> +    ASSERT(p.count <= *reps);
> +    *reps = vio->io_req.count = p.count;
> +
>      switch ( rc )
>      {
>      case X86EMUL_OKAY:
> 
> 


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