linux-kernel - RE: [PATCH v1 15/23] KVM: nVMX: Add support for the secondary VM exit controls

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Message-ID: <SA1PR11MB67344F9713F27B95454B73C5A8B4A@SA1PR11MB6734.namprd11.prod.outlook.com>
Date:   Mon, 20 Nov 2023 17:42:21 +0000
From:   "Li, Xin3" <xin3.li@...el.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>
CC:     "seanjc@...gle.com" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "corbet@....net" <corbet@....net>,
        "kys@...rosoft.com" <kys@...rosoft.com>,
        "haiyangz@...rosoft.com" <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        "Cui, Dexuan" <decui@...rosoft.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>
Subject: RE: [PATCH v1 15/23] KVM: nVMX: Add support for the secondary VM exit
 controls

> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h
> > b/arch/x86/include/asm/hyperv-tlfs.h
> > index 2ff26f53cd62..299554708e37 100644
> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > @@ -616,6 +616,7 @@ struct hv_enlightened_vmcs {
> >  	u64 host_ssp;
> >  	u64 host_ia32_int_ssp_table_addr;
> >  	u64 padding64_6;
> > +	u64 secondary_vm_exit_controls;
> 
> (I think Jeremi has asked a similar question but just to be sure)
> 
> This doesn't seem to be present in the currently available TLFS version e.g. here:
> https://learn.microsoft.com/en-us/virtualization/hyper-v-on-
> windows/tlfs/datatypes/hv_vmx_enlightened_vmcs
> 
> That wouldn't be the first time when TLFS lags behind but as I don't see anyone
> from Microsoft signing this off, let me ask: where did you get this information
> and, in case it came from someone @microsoft.com, can we get their sign-off on
> the patch?

This is being worked on.

> > diff --git a/arch/x86/kvm/vmx/hyperv.c b/arch/x86/kvm/vmx/hyperv.c
> > index 313b8bb5b8a7..b8cd53601a00 100644
> > --- a/arch/x86/kvm/vmx/hyperv.c
> > +++ b/arch/x86/kvm/vmx/hyperv.c
> > @@ -477,6 +483,9 @@ static const u32
> evmcs_supported_ctrls[NR_EVMCS_CTRLS][NR_EVMCS_REVISIONS] = {
> >  	[EVMCS_EXIT_CTRLS] = {
> >  		[EVMCSv1_LEGACY] = EVMCS1_SUPPORTED_VMEXIT_CTRL,
> >  	},
> > +	[EVMCS_2NDEXIT] = {
> > +		[EVMCSv1_LEGACY] = EVMCS1_SUPPORTED_VMEXIT_CTRL2,
> > +	},
> >  	[EVMCS_ENTRY_CTRLS] = {
> >  		[EVMCSv1_LEGACY] = EVMCS1_SUPPORTED_VMENTRY_CTRL,
> >  	},
> 
> What's the desired effect here? I.e. why exposing
> VM_EXIT_ACTIVATE_SECONDARY_CONTROLS when none of the controls are
> going to be exposed?
 
This is wrong for evmcs v1, I will drop it.