Re: [PATCH v4 4/9] KVM: nVMX: check GUEST_IA32_PERF_GLOBAL_CTRL on VM-Entry

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Fri, Sep 06, 2019 at 02:03:08PM -0700, Oliver Upton wrote:
> Add condition to nested_vmx_check_guest_state() to check the validity of
> GUEST_IA32_PERF_GLOBAL_CTRL. Per Intel's SDM Vol 3 26.3.1.1:
> 
>   If the "load IA32_PERF_GLOBAL_CTRL" VM-entry control is 1, bits
>   reserved in the IA32_PERF_GLOBAL_CTRL MSR must be 0 in the field for that
>   register.
> 
> Suggested-by: Jim Mattson <jmattson@google.com>
> Co-developed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
> Signed-off-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 9ba90b38d74b..6c3aa3bcede3 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -10,6 +10,7 @@
>  #include "hyperv.h"
>  #include "mmu.h"
>  #include "nested.h"
> +#include "pmu.h"
>  #include "trace.h"
>  #include "x86.h"
>  
> @@ -2732,6 +2733,7 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
>  					u32 *exit_qual)
>  {
>  	bool ia32e;
> +	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

Nit: I wouldn't bother with a local variable, just call vcpu_to_pmu() when
invoking kvm_is_valid_perf_global_ctrl(), especially since you need a line
break anyways.

>  
>  	*exit_qual = ENTRY_FAIL_DEFAULT;
>  
> @@ -2748,6 +2750,11 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
>  		return -EINVAL;
>  	}
>  
> +	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL &&
> +	    !kvm_is_valid_perf_global_ctrl(pmu,
> +					   vmcs12->guest_ia32_perf_global_ctrl))
> +		return -EINVAL;
> +
>  	/*
>  	 * If the load IA32_EFER VM-entry control is 1, the following checks
>  	 * are performed on the field for the IA32_EFER MSR:
> -- 
> 2.23.0.187.g17f5b7556c-goog
>