Re: [Xen-devel] [PATCH 2/4 v2] x86/EPT: refine direct MMIO checking when determining EMT

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Friday, April 25, 2014 8:06 PM
> 
> With need_iommu() only ever true when iommu_enabled is also true, and
> with the former getting set when a PCI device gets added to a guest,
> the checks can be consolidated. The range set check are left in place
> just in case raw MMIO or I/O port ranges get passed to a guest.
> 
> At once drop open-coding of cache_flush_permitted().
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> v2: Also drop open-coding of cache_flush_permitted().
> 
> --- a/xen/arch/x86/hvm/mtrr.c
> +++ b/xen/arch/x86/hvm/mtrr.c
> @@ -20,6 +20,7 @@
>  #include <public/hvm/e820.h>
>  #include <xen/types.h>
>  #include <asm/e820.h>
> +#include <asm/iocap.h>
>  #include <asm/mm.h>
>  #include <asm/paging.h>
>  #include <asm/p2m.h>
> @@ -810,10 +811,7 @@ int epte_get_entry_emt(struct domain *d,
>          return -1;
>      }
> 
> -    if ( !iommu_enabled ||
> -         (rangeset_is_empty(d->iomem_caps) &&
> -          rangeset_is_empty(d->arch.ioport_caps) &&
> -          !has_arch_pdevs(d)) )
> +    if ( !need_iommu(d) && !cache_flush_permitted(d) )

&&->||

>      {
>          ASSERT(!direct_mmio ||
>                 !((mfn_x(mfn) ^
> d->arch.hvm_domain.vmx.apic_access_mfn) >>
> 

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