linux-kernel - Re: [PATCH Part2 v6 04/49] x86/sev: set SYSCFG.MFMD

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Date:   Thu, 21 Jul 2022 13:29:01 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, jmattson@...gle.com, luto@...nel.org,
        dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
        peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
        rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com,
        michael.roth@....com, vbabka@...e.cz, kirill@...temov.name,
        ak@...ux.intel.com, tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
        dgilbert@...hat.com, jarkko@...nel.org
Subject: Re: [PATCH Part2 v6 04/49] x86/sev: set SYSCFG.MFMD

On Mon, Jun 20, 2022 at 11:02:18PM +0000, Ashish Kalra wrote:
> Subject: [PATCH Part2 v6 04/49] x86/sev: set SYSCFG.MFMD

That subject title needs to be made human readable.

> From: Brijesh Singh <brijesh.singh@....com>
> 
> SEV-SNP FW >= 1.51 requires that SYSCFG.MFMD must be set.

Because?

Also, commit message needs to be human-readable and not pseudocode.

> @@ -2325,6 +2346,9 @@ static __init int __snp_rmptable_init(void)
>  	/* Flush the caches to ensure that data is written before SNP is enabled. */
>  	wbinvd_on_all_cpus();
>  
> +	/* MFDM must be enabled on all the CPUs prior to enabling SNP. */
> +	on_each_cpu(mfdm_enable, NULL, 1);
> +
>  	/* Enable SNP on all CPUs. */
>  	on_each_cpu(snp_enable, NULL, 1);

No, not two IPI generating function calls - one and do everything in it.
I.e., what Marc said.

Thx.

-- 
Regards/Gruss,
    Boris.

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