linux-kernel - Re: [PATCH Part2 v5 20/45] KVM: SVM: Provide the Hypervisor Feature support VMGEXIT

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Date:   Tue, 12 Oct 2021 20:38:23 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH Part2 v5 20/45] KVM: SVM: Provide the Hypervisor Feature
 support VMGEXIT

On Fri, Aug 20, 2021, Brijesh Singh wrote:
> Version 2 of the GHCB specification introduced advertisement of features
> that are supported by the Hypervisor.
> 
> Now that KVM supports version 2 of the GHCB specification, bump the
> maximum supported protocol version.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/include/asm/sev-common.h |  2 ++
>  arch/x86/kvm/svm/sev.c            | 14 ++++++++++++++
>  arch/x86/kvm/svm/svm.h            |  3 ++-
>  3 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index d70a19000953..779c7e8f836c 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -97,6 +97,8 @@ enum psc_op {
>  /* GHCB Hypervisor Feature Request/Response */
>  #define GHCB_MSR_HV_FT_REQ		0x080
>  #define GHCB_MSR_HV_FT_RESP		0x081
> +#define GHCB_MSR_HV_FT_POS		12
> +#define GHCB_MSR_HV_FT_MASK		GENMASK_ULL(51, 0)
>  #define GHCB_MSR_HV_FT_RESP_VAL(v)			\
>  	/* GHCBData[63:12] */				\
>  	(((u64)(v) & GENMASK_ULL(63, 12)) >> 12)
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 0ca5b5b9aeef..1644da5fc93f 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2184,6 +2184,7 @@ 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_FEATURES:
>  		break;
>  	default:
>  		goto vmgexit_err;
> @@ -2438,6 +2439,13 @@ 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: {

Unnecessary braces.

> +		set_ghcb_msr_bits(svm, GHCB_HV_FT_SUPPORTED,
> +				  GHCB_MSR_HV_FT_MASK, GHCB_MSR_HV_FT_POS);
> +		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;
>  
> @@ -2553,6 +2561,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
>  		ret = 1;
>  		break;
>  	}
> +	case SVM_VMGEXIT_HV_FEATURES: {

Same here.

> +		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",