linux-kernel - [PATCH 1/4] x86/microcode: Remove unnecessary paravirt

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Message-Id: <1455612202-14414-2-git-send-email-bp@alien8.de>
Date:	Tue, 16 Feb 2016 09:43:19 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/4] x86/microcode: Remove unnecessary paravirt_enabled check

From: Boris Ostrovsky <boris.ostrovsky@...cle.com>

Commit

  a18a0f6850d4 ("x86, microcode: Don't initialize microcode code on paravirt")

added a paravirt test in microcode_init(), primarily to avoid making
mc_bp_resume()->load_ucode_ap()->check_loader_disabled_ap() calls
because on 32-bit kernels this callchain ends up using __pa_nodebug()
macro which is invalid for Xen PV guests.

A subsequent commit

  fbae4ba8c4a3 ("x86, microcode: Reload microcode on resume")

eliminated this callchain thus making a18a0f6850d4 unnecessary.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: david.vrabel@...rix.com
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: konrad.wilk@...cle.com
Cc: mingo@...hat.com
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: x86-ml <x86@...nel.org>
Cc: xen-devel@...ts.xenproject.org
Link: http://lkml.kernel.org/r/1455203598-14378-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/microcode/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index faec7120c508..86ec92a0bbbe 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -630,7 +630,7 @@ int __init microcode_init(void)
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 	int error;
 
-	if (paravirt_enabled() || dis_ucode_ldr)
+	if (dis_ucode_ldr)
 		return -EINVAL;
 
 	if (c->x86_vendor == X86_VENDOR_INTEL)
-- 
2.3.5