linux-kernel - Re: [Part2 PATCH v5.2 12.2/31] crypto: ccp: Add Secure Encrypted Virtualization (SEV) command support

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Date:   Thu, 12 Oct 2017 23:41:20 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Gary Hook <gary.hook@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-crypto@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Part2 PATCH v5.2 12.2/31] crypto: ccp: Add Secure Encrypted
 Virtualization (SEV) command support

On Thu, Oct 12, 2017 at 04:11:18PM -0500, Brijesh Singh wrote:
> The sev_exit() will be called for all the psp_device instance. we need
> to set psp_misc_dev = NULL after deregistering the device.
> 
> if (psp_misc_dev) {
>   misc_deregister(psp_misc_dev);
>    psp_misc_dev = NULL;

Right, except we assign that misc device to every psp device:

	psp->sev_misc = psp_misc_dev;

so the question now is, how do you want this to work: the misc device
should be destroyed after the last psp device is destroyed or how?

Because after the first:

	psp_misc_dev = NULL;

the respective psp->sev_misc will still keep references to that device
but the device itself will be already deregistered. And that sounds
strange.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--