linux-kernel - Re: [PATCH v2 2/8] x86/mtrr: support setting MTRR state for software defined MTRRs

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Message-ID: <20230214004510.4qfcsxjy3sqbzl5z@box.shutemov.name>
Date:   Tue, 14 Feb 2023 03:45:10 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Juergen Gross <jgross@...e.com>
Cc:     Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
        x86@...nel.org, lists@...dbynature.de, mikelley@...rosoft.com,
        torvalds@...ux-foundation.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 2/8] x86/mtrr: support setting MTRR state for software
 defined MTRRs

On Mon, Feb 13, 2023 at 03:07:07PM +0100, Juergen Gross wrote:
> > So this here needs to check:
> > 
> > 	if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR) &&
> > 	    !(cpu_feature_enabled(X86_FEATURE_SEV_SNP) ||
> > 	      cpu_feature_enabled(X86_FEATURE_XENPV))) {
> > 		WARN_ON_ONCE(1);
> > 		return;
> > 	}
> > 
> > as we don't want this to be called somewhere or by something else.
> 
> Wouldn't !cpu_feature_enabled(X86_FEATURE_HYPERVISOR) be enough?
> 
> I'm not sure we won't need that for TDX guests, too.

TDX guests are covered by X86_FEATURE_HYPERVISOR.


-- 
  Kiryl Shutsemau / Kirill A. Shutemov