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

From: Tom Lendacky
Date: Tue Jul 13 2021 - 09:35:23 EST


On 7/13/21 4:35 AM, Joerg Roedel wrote:
> From: Brijesh Singh <brijesh.singh@xxxxxxx>
>
> Version 2 of the GHCB specification introduced advertisement of features
> that are supported by the Hypervisor.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
> ---
> 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;
>
>