Re: [Xen-devel] [PATCH v3 5/6] x86/msr: update domain policy on CPUID policy changes

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/10/17 13:35, Sergey Dyasli wrote:
> Availability of some MSRs depends on certain CPUID bits. Add function
> recalculate_domain_msr_policy() which updates availability of per-domain
> MSRs based on current domain's CPUID policy. This function is called
> when CPUID policy is changed from a toolstack.

This is probably acceptable for now.  recalculate_cpuid_policy() is only
a transitory artefact between the current behaviour of the Xen, and the
future behaviour of auditing the toolstack-provided cpuid and msr policy
completely before changing the domains datastructures.

> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 205b4cb685..7e6b15f8d7 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -928,9 +928,8 @@ const char *hvm_efer_valid(const struct vcpu *v, uint64_t 
> value,
>          X86_CR0_CD | X86_CR0_PG)))
>  
>  /* These bits in CR4 can be set by the guest. */
> -unsigned long hvm_cr4_guest_valid_bits(const struct vcpu *v, bool restore)
> +unsigned long hvm_cr4_domain_valid_bits(const struct domain *d, bool restore)
>  {
> -    const struct domain *d = v->domain;
>      const struct cpuid_policy *p;
>      bool mce, vmxe;
>  
> @@ -963,6 +962,11 @@ unsigned long hvm_cr4_guest_valid_bits(const struct vcpu 
> *v, bool restore)
>              (p->feat.pku      ? X86_CR4_PKE               : 0));
>  }
>  
> +unsigned long hvm_cr4_guest_valid_bits(const struct vcpu *v, bool restore)

I'd split this change out into a separate patch and change the existing
guest valid bits to taking a domain *.

It needed to take vcpu in the past because of the old cpuid
infrastructure, but it doesn't need to any more because of the
domain-wide struct cpuid policy.

~Andrew

> +{
> +    return hvm_cr4_domain_valid_bits(v->domain, restore);
> +}
> +
>  static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h)
>  {
>      int vcpuid;
>


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