Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v15 14/14] KVM: x86: Save/Restore GUEST_SSP to/from SMRAM
To:     Yang Weijiang <weijiang.yang@intel.com>, seanjc@google.com,
        jmattson@google.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     yu.c.zhang@linux.intel.com
References: <20210203113421.5759-1-weijiang.yang@intel.com>
 <20210203113421.5759-15-weijiang.yang@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <55e43685-f4a7-b068-8d4c-931b8789f031@redhat.com>
Date:   Wed, 3 Feb 2021 13:07:53 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.0
MIME-Version: 1.0
In-Reply-To: <20210203113421.5759-15-weijiang.yang@intel.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

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.

Paolo