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From: Paolo Bonzini <pbonzini@redhat.com>
To: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm list <kvm@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	lkft-triage@lists.linaro.org, regressions@lists.linux.dev
Subject: Re: [PATCH 3/4] KVM: x86: WARN and reject loading KVM if NX is supported but not enabled
Date: Wed, 7 Jul 2021 16:15:49 +0200	[thread overview]
Message-ID: <40623553-310a-68f7-2981-f8ea9c7bd5b0@redhat.com> (raw)
In-Reply-To: <CA+G9fYsrQo3FvtW1VhXocY2xkaPLNADA4S5f=fBM5uqa=C5LYg@mail.gmail.com>

On 07/07/21 14:09, Naresh Kamboju wrote:
> On Fri, 25 Jun 2021 at 14:35, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 25/06/21 00:33, Sean Christopherson wrote:
>>> On Tue, Jun 15, 2021, Sean Christopherson wrote:
>>>> WARN if NX is reported as supported but not enabled in EFER.  All flavors
>>>> of the kernel, including non-PAE 32-bit kernels, set EFER.NX=1 if NX is
>>>> supported, even if NX usage is disable via kernel command line.
>>>
>>> Ugh, I misread .Ldefault_entry in head_32.S, it skips over the entire EFER code
>>> if PAE=0.  Apparently I didn't test this with non-PAE paging and EPT?
>>>
>>> Paolo, I'll send a revert since it's in kvm/next, but even better would be if
>>> you can drop the patch :-)  Lucky for me you didn't pick up patch 4/4 that
>>> depends on this...
>>>
>>> I'll revisit this mess in a few weeks.
>>
>> Rather, let's keep this, see if anyone complains and possibly add a
>> "depends on X86_PAE || X86_64" to KVM.
> 
> [ please ignore if this is already reported ]
> 
> The following kernel warning noticed while booting linus master branch and
> Linux next 20210707 tag on i386 kernel booting on x86_64 machine.

Ok, so the "depends on" is needed.  Let's add it, I'm getting back to 
KVM work and will send the patch today or tomorrow.

Paolo


  reply	other threads:[~2021-07-07 14:15 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 16:45 [PATCH 0/4] KVM: x86: Require EFER.NX support unless EPT is on Sean Christopherson
2021-06-15 16:45 ` [PATCH 1/4] KVM: VMX: Refuse to load kvm_intel if EPT and NX are disabled Sean Christopherson
2021-06-15 22:26   ` Jim Mattson
2021-06-15 16:45 ` [PATCH 2/4] KVM: SVM: Refuse to load kvm_amd if NX support is not available Sean Christopherson
2021-06-15 22:30   ` Jim Mattson
2021-06-15 16:45 ` [PATCH 3/4] KVM: x86: WARN and reject loading KVM if NX is supported but not enabled Sean Christopherson
2021-06-15 22:39   ` Jim Mattson
2021-06-18 10:27     ` Paolo Bonzini
2021-06-24 22:33   ` Sean Christopherson
2021-06-25  9:04     ` Paolo Bonzini
2021-07-07 12:09       ` Naresh Kamboju
2021-07-07 14:15         ` Paolo Bonzini [this message]
2021-06-15 16:45 ` [PATCH 4/4] KVM: x86: Simplify logic to handle lack of host NX support Sean Christopherson
2021-06-15 22:58   ` Jim Mattson
2021-06-15 23:33     ` Sean Christopherson
2021-06-18 10:31       ` Paolo Bonzini
2021-06-18 10:32 ` [PATCH 0/4] KVM: x86: Require EFER.NX support unless EPT is on Paolo Bonzini

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