linux-kernel - Re: [PATCH v2 14/25] KVM: VMX: Disable FRED if FRED consistency checks fail

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Message-ID: <ZmszxgbIbYSaXyjW@google.com>
Date: Thu, 13 Jun 2024 11:00:38 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Chao Gao <chao.gao@...el.com>
Cc: Xin Li <xin3.li@...el.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, 
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, 
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>, 
	"pbonzini@...hat.com" <pbonzini@...hat.com>, "corbet@....net" <corbet@....net>, 
	"tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>, 
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, 
	"hpa@...or.com" <hpa@...or.com>, "shuah@...nel.org" <shuah@...nel.org>, 
	"vkuznets@...hat.com" <vkuznets@...hat.com>, "peterz@...radead.org" <peterz@...radead.org>, 
	Ravi V Shankar <ravi.v.shankar@...el.com>, "xin@...or.com" <xin@...or.com>
Subject: Re: [PATCH v2 14/25] KVM: VMX: Disable FRED if FRED consistency
 checks fail

On Tue, Apr 30, 2024, Chao Gao wrote:
> On Thu, Feb 08, 2024 at 01:26:34AM +0800, Xin Li wrote:
> >Refuse to virtualize FRED if FRED consistency checks fail.
> 
> After reading this, I realize some consistency checks are missing in
> setup_vmcs_config(). Actually Sean requested some infrastructure for
> vmcs_entry_exit_pairs to deal with secondary_vmexit_ctrl.

Yeah, this belongs in setup_vmcs_config(), e.g. to guarantee that discrepancies
between CPUs are detected.  I would also strongly prefer this be squashed with
the patch(es) that introduce recognition of the FRED fields, if only so that we
can avoid "consistency checks" in the shortlog (I thought this patch was going
to disable FRED if a VM-Enter consistency check failed, which would be... interesting).