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From: Sean Christopherson <seanjc@google.com>
To: Kai Huang <kai.huang@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org, linux-sgx@vger.kernel.org, bp@alien8.de,
	jarkko@kernel.org, dave.hansen@intel.com, luto@kernel.org,
	rick.p.edgecombe@intel.com, haitao.huang@intel.com
Subject: Re: [PATCH v5 10/11] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC
Date: Mon, 19 Apr 2021 15:16:38 +0000	[thread overview]
Message-ID: <YH2e1lIckOBY2OGa@google.com> (raw)
In-Reply-To: <3d376fef419077376eecb017ab494ba7ffc393a7.camel@intel.com>

On Mon, Apr 19, 2021, Kai Huang wrote:
> On Sat, 2021-04-17 at 16:11 +0200, Paolo Bonzini wrote:
> > On 12/04/21 06:21, Kai Huang wrote:
> > > @@ -4377,6 +4380,15 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> > >   	if (!vcpu->kvm->arch.bus_lock_detection_enabled)
> > >   		exec_control &= ~SECONDARY_EXEC_BUS_LOCK_DETECTION;
> > >   
> > > 
> > > +	if (cpu_has_vmx_encls_vmexit() && nested) {
> > > +		if (guest_cpuid_has(vcpu, X86_FEATURE_SGX))
> > > +			vmx->nested.msrs.secondary_ctls_high |=
> > > +				SECONDARY_EXEC_ENCLS_EXITING;
> > > +		else
> > > +			vmx->nested.msrs.secondary_ctls_high &=
> > > +				~SECONDARY_EXEC_ENCLS_EXITING;
> > > +	}
> > > +
> > 
> > This is incorrect, I've removed it.  The MSRs can only be written by 
> > userspace.

vmx_compute_secondary_exec_control() violates that left, right, and center, it's
just buried down in vmx_adjust_secondary_exec_control().  This is an open coded
version of that helper, sans the actual update to exec_control since ENCLS needs
to be conditionally intercepted even when it's exposed to the guest.

> > If SGX is disabled in the guest CPUID, nested_vmx_exit_handled_encls can 
> > just do:
> > 
> > 	if (!guest_cpuid_has(vcpu, X86_FEATURE_SGX) ||
> > 	    !nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENCLS_EXITING))
> > 		return false;
> > 
> > and the useless ENCLS exiting bitmap in vmcs12 will be ignored.
> > 
> > Paolo
> > 
> 
> Thanks for queuing this series!
> 
> Looks good to me. However if I read code correctly, in this way a side effect would be
> vmx->nested.msrs.secondary_ctls_high will always have SECONDARY_EXEC_ENCLS_EXITING bit
> set, even SGX is not exposed to guest, which means a guest can set this even SGX is not
> present, but I think it is OK since ENCLS exiting bitmap in vmcs12 will be ignored anyway
> in nested_vmx_exit_handled_encls() as you mentioned above.
> 
> Anyway, I have tested this code and it works at my side (by creating L2 with SGX support
> and running SGX workloads inside it).
> 
> Sean, please also comment if you have any.
> 
> 

  reply	other threads:[~2021-04-19 15:16 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-12  4:21 [PATCH v5 00/11] KVM SGX virtualization support (KVM part) Kai Huang
2021-04-12  4:21 ` [PATCH v5 01/11] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-04-12  4:21 ` [PATCH v5 02/11] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-04-12  4:21 ` [PATCH v5 03/11] KVM: x86: Add support for reverse CPUID lookup of scattered features Kai Huang
2021-04-17 13:39   ` Paolo Bonzini
2021-04-12  4:21 ` [PATCH v5 04/11] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features Kai Huang
2021-04-17 13:39   ` Paolo Bonzini
2021-04-12  4:21 ` [PATCH v5 05/11] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-04-12  4:21 ` [PATCH v5 06/11] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-04-12  4:21 ` [PATCH v5 07/11] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-04-12  4:21 ` [PATCH v5 08/11] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-04-17 13:55   ` Paolo Bonzini
2021-04-12  4:21 ` [PATCH v5 09/11] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-04-12  4:21 ` [PATCH v5 10/11] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-04-12  9:51   ` kernel test robot
2021-04-12 10:47     ` Kai Huang
2021-04-17 14:11   ` Paolo Bonzini
2021-04-19 11:44     ` Kai Huang
2021-04-19 15:16       ` Sean Christopherson [this message]
2021-04-19 17:14         ` Paolo Bonzini
2021-04-12  4:21 ` [PATCH v5 11/11] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-04-12 11:28   ` kernel test robot
2021-04-13 14:51 ` [PATCH v5 00/11] KVM SGX virtualization support (KVM part) Paolo Bonzini
2021-04-13 15:01   ` Borislav Petkov
2021-04-13 21:47     ` Kai Huang
2021-04-17 14:15 ` Paolo Bonzini

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