linux-kernel - Re: [PATCH v9 05/43] x86/compressed/64: Detect/setup SEV/SME features earlier in boot

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Date:   Wed, 2 Feb 2022 07:09:24 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Roth <michael.roth@....com>
Cc:     Brijesh Singh <brijesh.singh@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        brijesh.ksingh@...il.com, tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v9 05/43] x86/compressed/64: Detect/setup SEV/SME
 features earlier in boot

On Tue, Feb 01, 2022 at 06:52:12PM -0600, Michael Roth wrote:
> Since the kernel proper rdmsr()/wrmsr() definitions are getting pulled in via
> misc.h, I have to use a different name to avoid compiler errors. For now I've
> gone with rd_msr()/wr_msr(), but no problem changing those if needed.

Does that fix it too?

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 16ed360b6692..346c46d072c8 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -21,7 +21,6 @@
 
 #include <linux/linkage.h>
 #include <linux/screen_info.h>
-#include <linux/elf.h>
 #include <linux/io.h>
 #include <asm/page.h>
 #include <asm/boot.h>
---

This is exactly what I mean with a multi-year effort of untangling what
has been mindlessly mixed in over the years...

> Since the rd_msr/wr_msr are oneliners, it seemed like it might be a
> little cleaner to just define them in boot/msr.h as static inline and
> include them directly as part of the header.

Ok, that's fine too.

> Here's what it looks like on top of this tree, and roughly how I plan to
> split the patches for v10:
> 
> - define the rd_msr/wr_msr helpers
>   https://github.com/mdroth/linux/commit/982c6c5741478c8f634db8ac0ba36575b5eff946
> 
> - use the helpers in boot/compressed/sev.c and boot/cpucheck.c
>   https://github.com/mdroth/linux/commit/a16e11f727c01fc478d3b741e1bdd2fd44975d7c
> 
> For v10 though I'll likely just drop rd_sev_status_msr() completely and use
> rd_msr() directly.
> 
> Let me know if I should make any changes and I'll make sure to get those in for
> the next spin.

Yap, looks good.

Thanks for doing that!

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette