linux-kernel - Re: Can't boot as Xen dom0 due to commit fe055896

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Date:   Thu, 15 Dec 2016 18:17:55 +0100
From:   Borislav Petkov <bp@...e.de>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Juergen Gross <jgross@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>
Subject: Re: Can't boot as Xen dom0 due to commit fe055896

On Thu, Dec 15, 2016 at 12:00:22PM -0500, Boris Ostrovsky wrote:
> There is an error on AMD as well. We end up being called at
> load_microcode_amd() with size=0 and crash soon after.

Does that fix it?

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index dd47e60aabf5..e238119b5dff 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1202,6 +1202,7 @@ config X86_REBOOTFIXUPS
 config MICROCODE
 	bool "CPU microcode loading support"
 	default y
+	depends on !XEN
 	depends on CPU_SUP_AMD || CPU_SUP_INTEL
 	select FW_LOADER
 	---help---

> (As a side note, I think verify_and_add_patch() should return error
> codes and not crnt_size, which may be a positive number. Which it was in
> my case.)

It does return negative values when there's some failure. It returns
crnt_size which can be a positive number so that we can advance to the
next patch in the blob.

-- 
Regards/Gruss,
    Boris.

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