linux-kernel - Re: [PATCH v8 2/7] KVM: VMX: Define CET VMCS fields and #CP flag

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Date:   Wed, 11 Dec 2019 09:45:36 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Yang Weijiang <weijiang.yang@...el.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, pbonzini@...hat.com,
        jmattson@...gle.com, yu.c.zhang@...ux.intel.com,
        yu-cheng.yu@...el.com
Subject: Re: [PATCH v8 2/7] KVM: VMX: Define CET VMCS fields and #CP flag

On Tue, Dec 10, 2019 at 01:00:44PM -0800, Sean Christopherson wrote:
> On Fri, Nov 01, 2019 at 04:52:17PM +0800, Yang Weijiang wrote:
> > CET(Control-flow Enforcement Technology) is an upcoming Intel(R)
> > processor feature that blocks Return/Jump-Oriented Programming(ROP)
> > attacks. It provides the following capabilities to defend
> > against ROP/JOP style control-flow subversion attacks:
> > 
> >  	return (1U << vector) & exception_has_error_code;
> >  }
> > @@ -298,7 +298,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
> >   * Right now, no XSS states are used on x86 platform,
> >   * expand the macro for new features.
> 
> I assume this comment needs to be updated?
>
I'm not sure which features in upstream code are using xsaves bits,
should I go like this:
In future, other XSS state bits can be added here to make them available
to guest? 
> >   */
> > -#define KVM_SUPPORTED_XSS	0
> > +#define KVM_SUPPORTED_XSS	(XFEATURE_MASK_CET_USER \
> > +				| XFEATURE_MASK_CET_KERNEL)
> >  
> >  extern u64 host_xcr0;
> >  
> > -- 
> > 2.17.2
> >