Re: [Xen-devel] [PATCH 06/14] Nested Virtualization: CRn & paged real mode

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

> Allow paged real mode during vmrun emulation.
> Emulate cr0 and cr4 when guest does not intercept them.

I understand the paged-real-mode case, but why do you also allow CR0.CD
and CR0.NW for nested VMs?

Cheers,

Tim.

> diff -r 917f9eb07fc3 -r b1a356e5658d xen/arch/x86/hvm/hvm.c
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -54,6 +54,7 @@
>  #include <asm/hvm/support.h>
>  #include <asm/hvm/cacheattr.h>
>  #include <asm/hvm/trace.h>
> +#include <asm/hvm/nestedhvm.h>
>  #include <asm/mtrr.h>
>  #include <asm/apic.h>
>  #include <public/sched.h>
> @@ -1105,7 +1106,8 @@ int hvm_set_cr0(unsigned long value)
>      /* ET is reserved and should be always be 1. */
>      value |= X86_CR0_ET;
>  
> -    if ( (value & (X86_CR0_PE | X86_CR0_PG)) == X86_CR0_PG )
> +    if ( !nestedhvm_vmentry_emulate(v) &&
> +         (value & (X86_CR0_PE | X86_CR0_PG)) == X86_CR0_PG )
>          goto gpf;
>  
>      if ( (value & X86_CR0_PG) && !(old_value & X86_CR0_PG) )
> @@ -1159,7 +1161,7 @@ int hvm_set_cr0(unsigned long value)
>          }
>      }
>  
> -    if ( has_arch_mmios(v->domain) )
> +    if ( !nestedhvm_vmentry_emulate(v) && has_arch_mmios(v->domain) )
>      {
>          if ( (value & X86_CR0_CD) && !(value & X86_CR0_NW) )
>          {

Content-Description: ATT00001..txt
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-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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