linux-kernel - Re: [PATCH 2/3] KVM: SVM: Add support for Hypervisor Feature support MSR protocol

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Date:   Tue, 13 Jul 2021 08:35:16 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Joerg Roedel <joro@...tes.org>, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org, x86@...nel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 2/3] KVM: SVM: Add support for Hypervisor Feature support
 MSR protocol

On 7/13/21 4:35 AM, Joerg Roedel wrote:
> From: Brijesh Singh <brijesh.singh@....com>
> 
> Version 2 of the GHCB specification introduced advertisement of features
> that are supported by the Hypervisor.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  arch/x86/include/asm/sev-common.h |  4 ++++
>  arch/x86/include/uapi/asm/svm.h   |  1 +
>  arch/x86/kvm/svm/sev.c            | 12 ++++++++++++
>  arch/x86/kvm/svm/svm.h            |  1 +
>  4 files changed, 18 insertions(+)
> 
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index dda34ecac5c0..0374f5687fc0 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -60,6 +60,10 @@
>  #define GHCB_MSR_HV_FT_REQ			0x080
>  #define GHCB_MSR_HV_FT_RESP			0x081
>  
> +/* GHCB Hypervisor Feature Request/Response */
> +#define GHCB_MSR_HV_FT_REQ			0x080
> +#define GHCB_MSR_HV_FT_RESP			0x081
> +

Looks like some of these definitions are already present, since the new
lines are the same as the lines above it.

Thanks,
Tom

>  #define GHCB_MSR_TERM_REQ		0x100
>  #define GHCB_MSR_TERM_REASON_SET_POS	12
>  #define GHCB_MSR_TERM_REASON_SET_MASK	0xf
> diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
> index efa969325ede..fbb6f8d27a80 100644
> --- a/arch/x86/include/uapi/asm/svm.h
> +++ b/arch/x86/include/uapi/asm/svm.h
> @@ -108,6 +108,7 @@
>  #define SVM_VMGEXIT_AP_JUMP_TABLE		0x80000005
>  #define SVM_VMGEXIT_SET_AP_JUMP_TABLE		0
>  #define SVM_VMGEXIT_GET_AP_JUMP_TABLE		1
> +#define SVM_VMGEXIT_HV_FT			0x8000fffd
>  #define SVM_VMGEXIT_UNSUPPORTED_EVENT		0x8000ffff
>  
>  /* Exit code reserved for hypervisor/software use */
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 0ec88b349799..8121b335651c 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2182,6 +2182,7 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
>  	case SVM_VMGEXIT_AP_HLT_LOOP:
>  	case SVM_VMGEXIT_AP_JUMP_TABLE:
>  	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
> +	case SVM_VMGEXIT_HV_FT:
>  		break;
>  	default:
>  		goto vmgexit_err;
> @@ -2434,6 +2435,11 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
>  				  GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);
>  		break;
>  	}
> +	case GHCB_MSR_HV_FT_REQ: {
> +		set_ghcb_msr_bits(svm, GHCB_HV_FT_SUPPORTED, GHCB_DATA_MASK, GHCB_DATA_LOW);
> +		set_ghcb_msr_bits(svm, GHCB_MSR_HV_FT_RESP, GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);
> +		break;
> +	}
>  	case GHCB_MSR_TERM_REQ: {
>  		u64 reason_set, reason_code;
>  
> @@ -2549,6 +2555,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
>  		ret = 1;
>  		break;
>  	}
> +	case SVM_VMGEXIT_HV_FT: {
> +		ghcb_set_sw_exit_info_2(ghcb, GHCB_HV_FT_SUPPORTED);
> +
> +		ret = 1;
> +		break;
> +	}
>  	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
>  		vcpu_unimpl(vcpu,
>  			    "vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index b21b9df54121..77379e1442cc 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -546,6 +546,7 @@ void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
>  #define GHCB_VERSION_MAX	1ULL
>  #define GHCB_VERSION_MIN	1ULL
>  
> +#define GHCB_HV_FT_SUPPORTED	0
>  
>  extern unsigned int max_sev_asid;
>  
>