Re: [Xen-devel] [PATCH 04/10] x86/hvm: pkeys, add pkeys support when setting CR4

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxx] On Behalf Of Huaitong Han
> Sent: Monday, November 16, 2015 6:32 PM
> To: jbeulich@xxxxxxxx; andrew.cooper3@xxxxxxxxxx; Nakajima, Jun
> <jun.nakajima@xxxxxxxxx>; Dong, Eddie <eddie.dong@xxxxxxxxx>; Tian,
> Kevin <kevin.tian@xxxxxxxxx>; george.dunlap@xxxxxxxxxxxxx;
> ian.jackson@xxxxxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx;
> ian.campbell@xxxxxxxxxx; wei.liu2@xxxxxxxxxx; keir@xxxxxxx
> Cc: Han, Huaitong <huaitong.han@xxxxxxxxx>; xen-devel@xxxxxxxxxxxxx
> Subject: [Xen-devel] [PATCH 04/10] x86/hvm: pkeys, add pkeys support when
> setting CR4
> 
> This patch adds pkeys support when setting CR4
> 
> Signed-off-by: Huaitong Han <huaitong.han@xxxxxxxxx>
> 
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 66917ff..953047f 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1911,6 +1911,7 @@ static unsigned long
> hvm_cr4_guest_reserved_bits(const struct vcpu *v,
>          leaf1_edx = boot_cpu_data.x86_capability[X86_FEATURE_VME / 32];
>          leaf1_ecx = boot_cpu_data.x86_capability[X86_FEATURE_PCID / 32];
>          leaf7_0_ebx = boot_cpu_data.x86_capability[X86_FEATURE_FSGSBASE /
> 32];
> +        leaf7_0_ecx = boot_cpu_data.x86_capability[X86_FEATURE_PKU / 32];

What is the purpose of the above change?

>      }
> 
>      return ~(unsigned long)
> @@ -1946,7 +1947,9 @@ static unsigned long
> hvm_cr4_guest_reserved_bits(const struct vcpu *v,
>               (leaf7_0_ebx & cpufeat_mask(X86_FEATURE_SMEP) ?
>                X86_CR4_SMEP : 0) |
>               (leaf7_0_ebx & cpufeat_mask(X86_FEATURE_SMAP) ?
> -              X86_CR4_SMAP : 0));
> +              X86_CR4_SMAP : 0) |
> +             (leaf7_0_ecx & cpufeat_mask(X86_FEATURE_PKU) ?
> +              X86_CR4_PKE : 0));
>  }
> 
>  static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h)
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index c1f924e..8101a1b 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1310,6 +1310,8 @@ void __init noreturn __start_xen(unsigned long
> mbi_p)
> 
>      if ( disable_pku )
>          setup_clear_cpu_cap(X86_FEATURE_PKU);
> +    if ( cpu_has_pku )
> +        set_in_cr4(X86_CR4_PKE);

As mentioned in [00/10] of this series, we shouldn't set PKE in CR4 for Xen
itself.

Thanks,
Feng

> 
>      if ( cpu_has_fsgsbase )
>          set_in_cr4(X86_CR4_FSGSBASE);
> --
> 2.4.3
> 
> 
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