linux-kernel - Re: [PATCH 40/70] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

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Date:   Wed, 15 Apr 2020 17:53:02 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Mike Stunes <mstunes@...are.com>
Cc:     Joerg Roedel <joro@...tes.org>, "x86@...nel.org" <x86@...nel.org>,
        "hpa@...or.com" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 40/70] x86/sev-es: Setup per-cpu GHCBs for the runtime
 handler

Hi Mike,

On Tue, Apr 14, 2020 at 07:03:44PM +0000, Mike Stunes wrote:
> set_memory_decrypted needs to check the return value. I see it
> consistently return ENOMEM. I've traced that back to split_large_page
> in arch/x86/mm/pat/set_memory.c.

I agree that the return code needs to be checked. But I wonder why this
happens. The split_large_page() function returns -ENOMEM when
alloc_pages() fails. Do you boot the guest with minal RAM assigned?

Regards,

	Joerg