From: Jarkko Sakkinen <jarkko@kernel.org>
To: Kai Huang <kai.huang@intel.com>
Cc: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org,
seanjc@google.com, luto@kernel.org, dave.hansen@intel.com,
haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de,
tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
jmattson@google.com, joro@8bytes.org, vkuznets@redhat.com,
wanpengli@tencent.com
Subject: Re: [RFC PATCH v3 16/27] KVM: VMX: Convert vcpu_vmx.exit_reason to a union
Date: Wed, 3 Feb 2021 00:41:00 +0200 [thread overview]
Message-ID: <YBnU/PZzKHkOIdW1@kernel.org> (raw)
In-Reply-To: <20210203082340.e808a4d97318e07b265d0326@intel.com>
On Wed, Feb 03, 2021 at 08:23:40AM +1300, Kai Huang wrote:
> On Tue, 2 Feb 2021 19:24:42 +0200 Jarkko Sakkinen wrote:
> > On Mon, Feb 01, 2021 at 01:32:59PM +1300, Kai Huang wrote:
> > > On Sat, 30 Jan 2021 17:00:46 +0200 Jarkko Sakkinen wrote:
> > > > On Tue, Jan 26, 2021 at 10:31:37PM +1300, Kai Huang wrote:
> > > > > From: Sean Christopherson <sean.j.christopherson@intel.com>
> > > > >
> > > > > Convert vcpu_vmx.exit_reason from a u32 to a union (of size u32). The
> > > > > full VM_EXIT_REASON field is comprised of a 16-bit basic exit reason in
> > > > > bits 15:0, and single-bit modifiers in bits 31:16.
> > > > >
> > > > > Historically, KVM has only had to worry about handling the "failed
> > > > > VM-Entry" modifier, which could only be set in very specific flows and
> > > > > required dedicated handling. I.e. manually stripping the FAILED_VMENTRY
> > > > > bit was a somewhat viable approach. But even with only a single bit to
> > > > > worry about, KVM has had several bugs related to comparing a basic exit
> > > > > reason against the full exit reason store in vcpu_vmx.
> > > > >
> > > > > Upcoming Intel features, e.g. SGX, will add new modifier bits that can
> >
> > BTW, SGX is not an upcoming CPU feature.
>
> Probably Sean was implying: "Upcoming CPU features that will be supported by
> Linux". I don't see big deal here.
>
> >
> > Also, broadly speaking of upcoming features is not right thing to do.
> > Better just to scope this down SGX. Theoretically upcoming CPU features
> > can do pretty much anything. This is change is first and foremost done
> > for SGX.
> >
> > > > > be set on more or less any VM-Exit, as opposed to the significantly more
> > > > > restricted FAILED_VMENTRY, i.e. correctly handling everything in one-off
> > > > > flows isn't scalable. Tracking exit reason in a union forces code to
> > > > > explicitly choose between consuming the full exit reason and the basic
> > > > > exit, and is a convenient way to document and access the modifiers.
> > > >
> > > > I *believe* that the change is correct but I dropped in the last paragraph
> > > > - most likely only because of lack of expertise in this area.
> > > >
> > > > I ask the most basic question: why SGX will add new modifier bits?
> > >
> > > Not 100% sure about your question. Assuming you are asking SGX hardware
> > > behavior, SGX architecture adds a new modifier bit (27) to Exit Reason, similar
> > > to new #PF.SGX bit.
> > >
> > > Please refer to SDM Volume 3, Chapter 27.2.1 Basic VM-Exit Information.
> > >
> > > Sean's commit msg already provides significant motivation of the change in this
> > > patch.
> >
> > Just describe why SGX requires this. That's all.
>
> This patch is to change vmexit info from u32 to union, because at least one
> additional modifier is going to be added, due to SGX. So the motivation of this
> patch is the fact that "one or more additional modifier bits will be added",
> and SGX is just example.
>
> So I don't think adding too much SGX backgroud in *THIS* patch is needed.
> And another patch:
>
> [RFC PATCH v3 21/27] KVM: VMX: Add basic handling of VM-Exit from SGX enclave
>
> already has enough information of "why new modifier bit is aadded for SGX".
> Sean also replied to you.
Well it comes after this patch. So you either need to provide the context
here or reorder patches. If latter is impossible, I would just add those
couple of paragraphs that Sean wrote.
> Please look at that patch and see whether it satisfies you.
Well there needs to be causality in patches. I should be able to review
the patches if 17-> did not exist.
>
> >
> > /Jarkko
>
/Jarkko
next prev parent reply other threads:[~2021-02-02 22:41 UTC|newest]
Thread overview: 156+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 10:10 [RFC PATCH v3 00/27] KVM SGX virtualization support Kai Huang
2021-01-26 9:29 ` Kai Huang
2021-01-26 9:30 ` [RFC PATCH v3 01/27] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-01-26 15:34 ` Dave Hansen
2021-01-26 23:18 ` Kai Huang
2021-01-30 13:20 ` Jarkko Sakkinen
2021-02-01 0:01 ` Kai Huang
2021-02-02 17:17 ` Jarkko Sakkinen
2021-02-03 1:09 ` Kai Huang
2021-02-02 17:56 ` Paolo Bonzini
2021-02-02 18:00 ` Dave Hansen
2021-02-02 18:03 ` Paolo Bonzini
2021-02-02 18:42 ` Sean Christopherson
2021-02-03 1:05 ` Kai Huang
2021-01-30 13:11 ` Jarkko Sakkinen
2021-01-26 9:30 ` [RFC PATCH v3 02/27] x86/cpufeatures: Make SGX_LC feature bit depend on SGX bit Kai Huang
2021-01-26 15:35 ` Dave Hansen
2021-01-30 13:22 ` Jarkko Sakkinen
2021-02-01 0:08 ` Kai Huang
2021-01-26 9:30 ` [RFC PATCH v3 03/27] x86/sgx: Remove a warn from sgx_free_epc_page() Kai Huang
2021-01-26 15:39 ` Dave Hansen
2021-01-26 16:30 ` Sean Christopherson
2021-01-27 1:08 ` Kai Huang
2021-01-27 1:12 ` Dave Hansen
2021-01-27 1:26 ` Kai Huang
2021-02-01 0:11 ` Kai Huang
2021-02-03 10:03 ` Jarkko Sakkinen
2021-01-26 9:30 ` [RFC PATCH v3 04/27] x86/sgx: Wipe out EREMOVE " Kai Huang
2021-01-26 16:04 ` Dave Hansen
2021-01-27 1:25 ` Kai Huang
2021-02-02 18:00 ` Paolo Bonzini
2021-02-02 19:25 ` Kai Huang
2021-02-02 19:02 ` Dave Hansen
2021-01-26 9:30 ` [RFC PATCH v3 05/27] x86/sgx: Add SGX_CHILD_PRESENT hardware error code Kai Huang
2021-01-26 15:49 ` Dave Hansen
2021-01-27 0:00 ` Kai Huang
2021-01-27 0:21 ` Dave Hansen
2021-01-27 0:52 ` Kai Huang
2021-01-26 9:30 ` [RFC PATCH v3 06/27] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-01-26 16:19 ` Dave Hansen
2021-01-27 0:16 ` Kai Huang
2021-01-27 0:27 ` Dave Hansen
2021-01-27 0:48 ` Kai Huang
2021-01-30 14:41 ` Jarkko Sakkinen
2021-01-26 9:30 ` [RFC PATCH v3 07/27] x86/cpu/intel: Allow SGX virtualization without Launch Control support Kai Huang
2021-01-26 16:26 ` Dave Hansen
2021-01-26 17:00 ` Sean Christopherson
2021-01-26 23:54 ` Kai Huang
2021-01-26 23:56 ` Kai Huang
2021-01-27 0:18 ` Dave Hansen
2021-01-27 2:02 ` Kai Huang
2021-01-27 17:13 ` Sean Christopherson
2021-01-30 14:42 ` Jarkko Sakkinen
2021-02-01 5:38 ` Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 08/27] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Kai Huang
2021-01-26 17:03 ` Dave Hansen
2021-01-26 18:10 ` Andy Lutomirski
2021-01-26 23:25 ` Kai Huang
2021-01-30 14:45 ` Jarkko Sakkinen
2021-02-01 5:40 ` Kai Huang
2021-02-01 15:25 ` Dave Hansen
2021-02-01 17:23 ` Sean Christopherson
2021-02-02 0:12 ` Kai Huang
2021-02-02 23:10 ` Jarkko Sakkinen
2021-02-02 23:07 ` Jarkko Sakkinen
2021-02-02 17:32 ` Jarkko Sakkinen
2021-02-02 18:20 ` Sean Christopherson
2021-02-02 23:16 ` Jarkko Sakkinen
2021-02-03 0:49 ` Kai Huang
2021-02-03 22:02 ` Jarkko Sakkinen
2021-02-03 22:59 ` Sean Christopherson
2021-02-04 1:39 ` Jarkko Sakkinen
2021-02-04 2:59 ` Kai Huang
2021-02-04 3:05 ` Jarkko Sakkinen
2021-02-04 3:09 ` Jarkko Sakkinen
2021-02-04 3:20 ` Kai Huang
2021-02-04 14:51 ` Jarkko Sakkinen
2021-02-04 22:41 ` Dave Hansen
2021-02-04 22:56 ` Kai Huang
2021-02-05 2:08 ` Jarkko Sakkinen
2021-02-05 3:00 ` Huang, Kai
2021-02-02 18:49 ` Kai Huang
2021-02-02 23:17 ` Jarkko Sakkinen
2021-01-26 9:31 ` [RFC PATCH v3 09/27] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-01-30 14:46 ` Jarkko Sakkinen
2021-01-26 9:31 ` [RFC PATCH v3 10/27] x86/sgx: Move ENCLS leaf definitions to sgx_arch.h Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 11/27] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 12/27] x86/sgx: Add encls_faulted() helper Kai Huang
2021-01-30 14:48 ` Jarkko Sakkinen
2021-01-26 9:31 ` [RFC PATCH v3 13/27] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-01-30 14:49 ` Jarkko Sakkinen
2021-02-01 1:17 ` Kai Huang
2021-02-01 21:22 ` Dave Hansen
2021-01-26 9:31 ` [RFC PATCH v3 14/27] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-01-30 14:51 ` Jarkko Sakkinen
2021-02-01 0:17 ` Kai Huang
2021-02-02 17:20 ` Jarkko Sakkinen
2021-02-02 20:35 ` Kai Huang
2021-02-04 3:53 ` Kai Huang
2021-02-05 0:32 ` Sean Christopherson
2021-02-05 1:39 ` Huang, Kai
2021-01-26 9:31 ` [RFC PATCH v3 15/27] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-01-30 14:52 ` Jarkko Sakkinen
2021-01-26 9:31 ` [RFC PATCH v3 16/27] KVM: VMX: Convert vcpu_vmx.exit_reason to a union Kai Huang
2021-01-30 15:00 ` Jarkko Sakkinen
2021-02-01 0:32 ` Kai Huang
2021-02-02 17:24 ` Jarkko Sakkinen
2021-02-02 19:23 ` Kai Huang
2021-02-02 22:41 ` Jarkko Sakkinen [this message]
2021-02-03 0:42 ` Kai Huang
2021-02-01 17:12 ` Sean Christopherson
2021-02-02 22:38 ` Jarkko Sakkinen
2021-01-26 9:31 ` [RFC PATCH v3 17/27] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 18/27] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 19/27] KVM: x86: Add support for reverse CPUID lookup of scattered features Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 20/27] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 21/27] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 22/27] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 23/27] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-02-03 0:52 ` Edgecombe, Rick P
2021-02-03 1:36 ` Sean Christopherson
2021-02-03 9:11 ` Kai Huang
2021-02-03 17:07 ` Sean Christopherson
2021-02-03 23:11 ` Kai Huang
2021-02-03 18:47 ` Edgecombe, Rick P
2021-02-03 19:36 ` Sean Christopherson
2021-02-03 23:29 ` Kai Huang
2021-02-03 23:36 ` Sean Christopherson
2021-02-03 23:45 ` Kai Huang
2021-02-03 23:59 ` Sean Christopherson
2021-02-04 0:11 ` Kai Huang
2021-02-04 2:01 ` Sean Christopherson
2021-01-26 9:31 ` [RFC PATCH v3 24/27] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 25/27] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-01-26 9:31 ` [RFC PATCH v3 26/27] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-01-26 9:32 ` [RFC PATCH v3 27/27] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-02-02 22:21 ` [RFC PATCH v3 00/27] KVM SGX virtualization support Edgecombe, Rick P
2021-02-02 22:33 ` Sean Christopherson
2021-02-02 23:21 ` Dave Hansen
2021-02-02 23:56 ` Sean Christopherson
2021-02-03 0:43 ` Dave Hansen
2021-02-03 15:10 ` Dave Hansen
2021-02-03 17:36 ` Sean Christopherson
2021-02-03 17:43 ` Paolo Bonzini
2021-02-03 17:46 ` Dave Hansen
2021-02-03 23:09 ` Kai Huang
2021-02-03 23:32 ` Sean Christopherson
2021-02-03 23:37 ` Dave Hansen
2021-02-04 0:04 ` Kai Huang
2021-02-04 0:28 ` Sean Christopherson
2021-02-04 3:18 ` Kai Huang
2021-02-04 16:28 ` Sean Christopherson
2021-02-04 16:48 ` Dave Hansen
2021-02-05 12:32 ` Kai Huang
2021-02-05 16:51 ` Sean Christopherson
2021-02-02 22:36 ` Dave Hansen
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