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Date:   Wed, 6 Dec 2023 18:08:07 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     "Kalra, Ashish" <ashish.kalra@amd.com>
Cc:     Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org,
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Subject: Re: [PATCH v10 14/50] crypto: ccp: Add support to initialize the
 AMD-SP for SEV-SNP
Message-ID: <20231206170807.GBZXCqd0z8uu2rlhpn@fat_crate.local>
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On Wed, Nov 29, 2023 at 08:13:52PM -0600, Kalra, Ashish wrote:
> It surely seems hard to follow up, so i am anyway going to clean it up by:
> 
> Adding the "probe" parameter to sev_platform_init() where the parameter
> being true indicates that we only want to do SNP initialization on probe,
> the same parameter will get passed on to
> __sev_platform_init_locked().

That's exactly what you should *not* do - the probe parameter controls
whether

	if (psp_init_on_probe)
		__sev_platform_init_locked(error);

and so on should get executed or not.

If it is unclear, lemme know and I'll do a diff to show you what I mean.
	
> > > +	/* Prepare for first SNP guest launch after INIT */
> > > +	wbinvd_on_all_cpus();
> > 
> > Why is that WBINVD needed?
> 
> As the comment above mentions, WBINVD + DF_FLUSH is needed before the first
> guest launch.

Lemme see if I get this straight. The correct order is:

	WBINVD
	SNP_INIT_*
	WBINVD
	DF_FLUSH

If so, do a comment which goes like this:

	/*
	 * The order of commands to execute before the first guest
	 * launch is the following:
	 *
	 * bla...
	 */


> In the latest code base, _sev_snp_shutdown_locked() is called from
> __sev_firmware_shutdown().

Then carve that function out only when needed - do not do changes
preemptively. This is not helping during review.

Thx.

-- 
Regards/Gruss,
    Boris.

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