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

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Message-ID: <BYAPR21MB168807498B89953E54CDAE3ED7A09@BYAPR21MB1688.namprd21.prod.outlook.com>
Date:   Thu, 16 Feb 2023 16:04:50 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Borislav Petkov <bp@...en8.de>, Juergen Gross <jgross@...e.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "lists@...dbynature.de" <lists@...dbynature.de>,
        "torvalds@...ux-foundation.org" <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

From: Borislav Petkov <bp@...en8.de> Sent: Thursday, February 16, 2023 4:29 AM
>
> On Thu, Feb 16, 2023 at 01:19:22PM +0100, Juergen Gross wrote:
> > Hmm, I must be blind. I can't spot it.
> >
> > I'm seeing only the feature bit #define and a call of
> > setup_clear_cpu_cap(X86_FEATURE_SEV_SNP) in this patch.
> >
> > Or is it done by hardware or the hypervisor?
> 
> Correction - I meant CC_ATTR_GUEST_SEV_SNP not the CPUID feature flag.
> 

In current upstream code, Hyper-V vTOM VMs aren't participating in
the CC_ATTR_* scheme at all, so CC_ATTR_GUEST_SEV_SNP won't be
set.   Getting Hyper-V vTOM VMs integrated into that scheme is a key
part of my big patch set[1] that we're separately trying to resolve the
last issues with.

Michael

[1] https://lore.kernel.org/linux-hyperv/1673559753-94403-1-git-send-email-mikelley@microsoft.com/