From: Kai Huang <kai.huang@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@intel.com>,
linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org,
jarkko@kernel.org, luto@kernel.org, haitao.huang@intel.com,
pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com,
hpa@zytor.com
Subject: Re: [RFC PATCH 04/23] x86/cpufeatures: Add SGX1 and SGX2 sub-features
Date: Tue, 12 Jan 2021 15:01:28 +1300 [thread overview]
Message-ID: <20210112150128.1e0d621e053bbbf210bcb946@intel.com> (raw)
In-Reply-To: <X/yk6zcJTLXJwIrJ@google.com>
On Mon, 11 Jan 2021 11:20:11 -0800 Sean Christopherson wrote:
> On Mon, Jan 11, 2021, Borislav Petkov wrote:
> > On Mon, Jan 11, 2021 at 09:54:17AM -0800, Sean Christopherson wrote:
> > > It would be possible for KVM to break the dependency on X86_FEATURE_* bit
> > > offsets by defining a translation layer, but I strongly feel that adding manual
> > > translations will do more harm than good as it increases the odds of us botching
> > > a translation or using the wrong feature flag, creates potential namespace
> > > conflicts, etc...
> >
> > Ok, lemme see if we might encounter more issues down the road...
> >
> > +enum kvm_only_cpuid_leafs {
> > + CPUID_12_EAX = NCAPINTS,
> > + NR_KVM_CPU_CAPS,
> > +
> > + NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
> > +};
> > +
> >
> > What happens when we decide to allocate a separate leaf for CPUID_12_EAX
> > down the road?
>
> Well, mechanically, that would generate a build failure if the kernel does the
> obvious things and names the 'enum cpuid_leafs' entry CPUID_12_EAX. That would
> be an obvious clue that KVM should be updated.
>
> If the kernel named the enum entry something different, and we botched the code
> review, KVM would continue to work, but would unnecessarily copy the bits it
> cares about to its own word. E.g. the boot_cpu_has() checks and translation to
> __X86_FEATURE_* would still be valid. As far as failure modes go, that's not
> terrible.
Should we add a dedicated, i.e. kvm_scattered_cpu_caps[], instead of using
existing kvm_cpu_cap[NCAPINTS]? If so this issue can be avoided??
>
> > You do it already here
> >
> > Subject: [PATCH 04/13] x86/cpufeatures: Assign dedicated feature word for AMD mem encryption
> >
> > for the AMD leaf.
> >
> > I'm thinking this way around - from scattered to a hw one - should be ok
> > because that should work easily. The other way around, taking a hw leaf
> > and scattering it around x86_capability[] array elems would probably be
> > nasty but with your change that should work too.
> >
> > Yah, I'm just hypothesizing here - I don't think this "other way around"
> > will ever happen...
> >
> > Hmm, yap, I can cautiously say that with your change we should be ok...
> >
> > Thx.
> >
> > --
> > Regards/Gruss,
> > Boris.
> >
> > https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-01-12 2:02 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 1:55 [RFC PATCH 00/23] KVM SGX virtualization support Kai Huang
2021-01-06 1:55 ` [RFC PATCH 01/23] x86/sgx: Split out adding EPC page to free list to separate helper Kai Huang
2021-01-11 22:38 ` Jarkko Sakkinen
2021-01-12 0:19 ` Kai Huang
2021-01-12 21:45 ` Sean Christopherson
2021-01-13 1:15 ` Kai Huang
2021-01-13 17:05 ` Jarkko Sakkinen
2021-01-06 1:55 ` [RFC PATCH 02/23] x86/sgx: Add enum for SGX_CHILD_PRESENT error code Kai Huang
2021-01-06 18:28 ` Dave Hansen
2021-01-06 21:40 ` Kai Huang
2021-01-12 0:26 ` Jarkko Sakkinen
2021-01-11 23:32 ` Jarkko Sakkinen
2021-01-12 0:16 ` Kai Huang
2021-01-12 1:46 ` Jarkko Sakkinen
2021-01-06 1:55 ` [RFC PATCH 03/23] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-01-06 19:35 ` Dave Hansen
2021-01-06 20:35 ` Sean Christopherson
2021-01-07 0:47 ` Kai Huang
2021-01-07 0:52 ` Dave Hansen
2021-01-07 1:38 ` Kai Huang
2021-01-07 5:00 ` Dave Hansen
2021-01-07 1:42 ` Kai Huang
2021-01-07 5:02 ` Dave Hansen
2021-01-15 14:07 ` Kai Huang
2021-01-15 15:39 ` Dave Hansen
2021-01-15 21:33 ` Kai Huang
2021-01-15 21:45 ` Sean Christopherson
2021-01-15 22:30 ` Kai Huang
2021-01-11 23:38 ` Jarkko Sakkinen
2021-01-12 0:56 ` Kai Huang
2021-01-12 1:50 ` Jarkko Sakkinen
2021-01-12 2:03 ` Kai Huang
2021-01-06 1:55 ` [RFC PATCH 04/23] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-01-06 19:39 ` Dave Hansen
2021-01-06 22:12 ` Kai Huang
2021-01-06 22:21 ` Dave Hansen
2021-01-06 22:56 ` Kai Huang
2021-01-06 23:19 ` Sean Christopherson
2021-01-06 23:33 ` Dave Hansen
2021-01-06 23:56 ` Kai Huang
2021-01-06 23:40 ` Kai Huang
2021-01-06 23:43 ` Dave Hansen
2021-01-06 23:56 ` Kai Huang
2021-01-06 22:15 ` Borislav Petkov
2021-01-06 23:09 ` Kai Huang
2021-01-07 6:41 ` Borislav Petkov
2021-01-08 2:00 ` Kai Huang
2021-01-08 5:10 ` Dave Hansen
2021-01-08 7:03 ` Kai Huang
2021-01-08 7:17 ` Borislav Petkov
2021-01-08 8:06 ` Kai Huang
2021-01-08 8:13 ` Borislav Petkov
2021-01-08 9:00 ` Kai Huang
2021-01-08 23:55 ` Sean Christopherson
2021-01-09 0:35 ` Borislav Petkov
2021-01-09 1:01 ` Sean Christopherson
2021-01-09 1:19 ` Borislav Petkov
2021-01-11 17:54 ` Sean Christopherson
2021-01-11 19:09 ` Borislav Petkov
2021-01-11 19:20 ` Sean Christopherson
2021-01-12 2:01 ` Kai Huang [this message]
2021-01-12 12:13 ` Borislav Petkov
2021-01-12 17:15 ` Sean Christopherson
2021-01-12 17:51 ` Borislav Petkov
2021-01-12 21:07 ` Kai Huang
2021-01-12 23:17 ` Sean Christopherson
2021-01-13 1:05 ` Kai Huang
2021-01-11 23:39 ` Jarkko Sakkinen
2021-01-06 1:55 ` [RFC PATCH 05/23] x86/cpu/intel: Allow SGX virtualization without Launch Control support Kai Huang
2021-01-06 19:54 ` Dave Hansen
2021-01-06 22:34 ` Kai Huang
2021-01-06 22:38 ` Dave Hansen
2021-01-06 1:56 ` [RFC PATCH 06/23] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-01-06 1:56 ` [RFC PATCH 07/23] x86/sgx: Move ENCLS leaf definitions to sgx_arch.h Kai Huang
2021-01-06 1:56 ` [RFC PATCH 08/23] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-01-06 1:56 ` [RFC PATCH 09/23] x86/sgx: Add encls_faulted() helper Kai Huang
2021-01-06 1:56 ` [RFC PATCH 10/23] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-01-06 19:56 ` Dave Hansen
2021-01-06 1:56 ` [RFC PATCH 11/23] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-01-06 20:12 ` Dave Hansen
2021-01-06 21:04 ` Sean Christopherson
2021-01-06 21:23 ` Dave Hansen
2021-01-06 22:58 ` Kai Huang
2021-01-06 1:56 ` [RFC PATCH 12/23] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-01-06 1:56 ` [RFC PATCH 13/23] KVM: VMX: Convert vcpu_vmx.exit_reason to a union Kai Huang
2021-01-06 1:56 ` [RFC PATCH 14/23] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-01-06 1:56 ` [RFC PATCH 15/23] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-01-06 1:56 ` [RFC PATCH 16/23] KVM: x86: Add SGX feature leaf to reverse CPUID lookup Kai Huang
2021-01-06 1:56 ` [RFC PATCH 17/23] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-01-06 1:56 ` [RFC PATCH 18/23] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-01-06 1:56 ` [RFC PATCH 19/23] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-01-06 1:56 ` [RFC PATCH 20/23] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-01-06 1:56 ` [RFC PATCH 21/23] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-01-06 1:56 ` [RFC PATCH 22/23] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-01-06 1:58 ` [RFC PATCH 23/23] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-01-06 2:22 ` [RFC PATCH 00/23] KVM SGX virtualization support Kai Huang
2021-01-06 17:07 ` Dave Hansen
2021-01-07 0:34 ` Kai Huang
2021-01-07 0:48 ` Dave Hansen
2021-01-07 1:50 ` Kai Huang
2021-01-07 16:14 ` Sean Christopherson
2021-01-08 2:16 ` Kai Huang
2021-01-11 17:20 ` Jarkko Sakkinen
2021-01-11 18:37 ` Sean Christopherson
2021-01-12 1:58 ` Jarkko Sakkinen
2021-01-12 1:14 ` Kai Huang
2021-01-12 2:02 ` Jarkko Sakkinen
2021-01-12 2:07 ` Kai Huang
2021-01-15 14:43 ` Kai Huang
2021-01-16 9:31 ` Jarkko Sakkinen
2021-01-16 9:50 ` Jarkko Sakkinen
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