From: Kai Huang <kai.huang@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: 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, bp@alien8.de, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com
Subject: Re: [RFC PATCH 04/23] x86/cpufeatures: Add SGX1 and SGX2 sub-features
Date: Thu, 7 Jan 2021 12:56:15 +1300 [thread overview]
Message-ID: <20210107125615.f11d6498ba119a6e2e7adacb@intel.com> (raw)
In-Reply-To: <X/ZFjUO83lDdQBPL@google.com>
On Wed, 6 Jan 2021 15:19:41 -0800 Sean Christopherson wrote:
> On Thu, Jan 07, 2021, Kai Huang wrote:
> > On Wed, 6 Jan 2021 14:21:39 -0800 Dave Hansen wrote:
> > > On 1/6/21 2:12 PM, Kai Huang wrote:
> > > > On Wed, 6 Jan 2021 11:39:46 -0800 Dave Hansen wrote:
> > > >> On 1/5/21 5:55 PM, Kai Huang wrote:
> > > >>> --- a/arch/x86/kernel/cpu/feat_ctl.c
> > > >>> +++ b/arch/x86/kernel/cpu/feat_ctl.c
> > > >>> @@ -97,6 +97,8 @@ static void clear_sgx_caps(void)
> > > >>> {
> > > >>> setup_clear_cpu_cap(X86_FEATURE_SGX);
> > > >>> setup_clear_cpu_cap(X86_FEATURE_SGX_LC);
> > > >>> + setup_clear_cpu_cap(X86_FEATURE_SGX1);
> > > >>> + setup_clear_cpu_cap(X86_FEATURE_SGX2);
> > > >>> }
> > > >> Logically, I think you want this *after* the "Allow SGX virtualization
> > > >> without Launch Control support" patch. As it stands, this will totally
> > > >> disable SGX (including virtualization) if launch control is unavailable.
> > > >>
> > > > To me it is better to be here, since clear_sgx_caps(), which disables SGX
> > > > totally, should logically clear all SGX feature bits, no matter later patch's
> > > > behavior. So when new SGX bits are introduced, clear_sgx_caps() should clear
> > > > them too. Otherwise the logic of this patch (adding new SGX feature bits) is
> > > > not complete IMHO.
> > > >
> > > > And actually in later patch "Allow SGX virtualization without Launch Control
> > > > support", a new clear_sgx_lc() is added, and is called when LC is not
> > > > available but SGX virtualization is enabled, to make sure only SGX_LC bit is
> > > > cleared in this case. I don't quite understand why we need to clear SGX1 and
> > > > SGX2 in clear_sgx_caps() after the later patch.
> > >
> > > I was talking about patch ordering. It could be argued that this goes
> > > after the content of patch 05/23. Please _consider_ changing the ordering.
> > >
> > > If that doesn't work for some reason, please at least call out in the
> > > changelog that it leaves a temporarily funky situation.
> > >
> >
> > The later patch currently uses SGX1 bit, which is the reason that this patch
> > needs be before later patch.
> >
> > Sean,
> >
> > I think it is OK to remove SGX1 bit check in later patch, since I have
> > never seen a machine with SGX bit in CPUID, but w/o SGX1.
>
> The SGX1 check is "needed" to handle the case where SGX is supported but was
> soft-disabled, e.g. because software disable a machine check bank by writing an
> MCi_CTL MSR.
>
> > If we remove SGX1 bit check in later, we can put this patch after the later
> > patch.
> >
> > Do you have comment here? If you are OK, I'll remove SGX1 bit check in later
> > patch and reorder the patch.
>
> Hmm, I'm not sure why the SGX driver was merged without explicitly checking for
> SGX1 support. I'm pretty sure we had an explicit SGX1 check in the driver path
> at some point. My guess is that the SGX1 change ended up in the KVM series
> through a mishandled rebase.
>
> Moving the check later won't break anything that's not already broken. But,
> arguably checking SGX1 is a bug fix of sorts, e.g. to guard against broken
> firmware, and should go in as a standalone patch destined for stable. The
> kernel can't prevent SGX from being soft-disabled after boot, but IMO it should
> cleanly handle the case where SGX was soft-disabled _before_ boot.
It seems I need to dig some history. Thanks Sean for the info!
next prev parent reply other threads:[~2021-01-06 23:57 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210107125615.f11d6498ba119a6e2e7adacb@intel.com \
--to=kai.huang@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@intel.com \
--cc=haitao.huang@intel.com \
--cc=hpa@zytor.com \
--cc=jarkko@kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-sgx@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).