linux-kernel - Re: [PATCHv2 0/4] x86/tdx: Adjust TD settings on boot

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Message-ID: <gpqnnq6zubgltybaruzbpvdd3k27exylp3bzmz6cqpvhx5ee5e@vto2bmdz7kji>
Date: Fri, 12 Apr 2024 18:01:58 +0300
From: "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc: "tglx@...utronix.de" <tglx@...utronix.de>, 
	"mingo@...hat.com" <mingo@...hat.com>, "Hansen, Dave" <dave.hansen@...el.com>, 
	"bp@...en8.de" <bp@...en8.de>, 
	"sathyanarayanan.kuppuswamy@...ux.intel.com" <sathyanarayanan.kuppuswamy@...ux.intel.com>, "hpa@...or.com" <hpa@...or.com>, 
	"Reshetova, Elena" <elena.reshetova@...el.com>, "seanjc@...gle.com" <seanjc@...gle.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCHv2 0/4] x86/tdx: Adjust TD settings on boot

On Wed, Apr 10, 2024 at 02:41:13PM +0000, Edgecombe, Rick P wrote:
> On Wed, 2024-04-10 at 17:37 +0300, Kirill A. Shutemov wrote:
> > On Mon, Mar 25, 2024 at 12:46:03PM +0200, Kirill A. Shutemov wrote:
> > > Adjust TD setting on boot:
> > > 
> > >    - Disable EPT violation #VE on private memory if TD can
> > >      control it;
> > > 
> > >    - Enable virtualization of topology-related CPUID leafs
> > >      X2APIC_APICID MSR;
> > 
> > Any feedback?
> 
> It is missing a lot of the normal things that come in coverletters like what is
> the problem and importance. It might help attract more review.

What about this:

The patchset adjusts a few TD settings on boot for the optimal functioning
of the system:

  - Disable EPT violation #VE on private memory if TD can control it

    The newer TDX module allows the guest to control whether it wants to
    see #VE on EPT violation on private memory. The Linux kernel does not
    want such #VEs and needs to disable them.

  - Enable virtualization of topology-related CPUID leafs X2APIC_APICID MSR;

    The ENUM_TOPOLOGY feature allows the VMM to provide topology
    information to the guest. Enabling the feature eliminates
    topology-related #VEs: the TDX module virtualizes accesses to the
    CPUID leafs and the MSR.

    It allows TDX guest to run with non-trivial topology configuration.
-- 
  Kiryl Shutsemau / Kirill A. Shutemov