linux-kernel - Re: [PATCH v15 14/14] KVM: x86: Save/Restore GUEST

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Date:   Wed, 3 Feb 2021 20:59:57 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Yang Weijiang <weijiang.yang@...el.com>, seanjc@...gle.com,
        jmattson@...gle.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, yu.c.zhang@...ux.intel.com
Subject: Re: [PATCH v15 14/14] KVM: x86: Save/Restore GUEST_SSP to/from SMRAM

On Wed, Feb 03, 2021 at 01:07:53PM +0100, Paolo Bonzini wrote:
> On 03/02/21 12:34, Yang Weijiang wrote:
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 22eb6b8626a8..f63b713cd71f 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -8592,6 +8592,16 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, char *buf)
> >   	for (i = 0; i < 6; i++)
> >   		enter_smm_save_seg_64(vcpu, buf, i);
> > +
> > +	if (kvm_cet_supported()) {
> > +		struct msr_data msr;
> > +
> > +		msr.index = MSR_KVM_GUEST_SSP;
> > +		msr.host_initiated = true;
> > +		/* GUEST_SSP is stored in VMCS at vm-exit. */
> > +		kvm_x86_ops.get_msr(vcpu, &msr);
> > +		put_smstate(u64, buf, 0x7ec8, msr.data);
> > +	}
> >   }
> >   #endif
> > 
> 
> 0x7ec8 is used for I/O instruction restart and auto-halt restart. 0x7f08 is
> a free spot.  We should really document the KVM state save area format.
Thanks for catching the documentation error! 
> 
> Paolo