linux-kernel - [tip:x86/urgent] x86/microcode/AMD: Use native_cpuid() in load_ucode_amd

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Message-ID: <tip-2b4c91569a40c4512ea1b413e0c817d179ce9868@git.kernel.org>
Date:   Mon, 19 Dec 2016 01:56:53 -0800
From:   tip-bot for Boris Ostrovsky <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, jgross@...e.com, tglx@...utronix.de,
        boris.ostrovsky@...cle.com, mingo@...nel.org, bp@...e.de,
        linux-kernel@...r.kernel.org
Subject: [tip:x86/urgent] x86/microcode/AMD: Use native_cpuid() in
 load_ucode_amd_bsp()

Commit-ID:  2b4c91569a40c4512ea1b413e0c817d179ce9868
Gitweb:     http://git.kernel.org/tip/2b4c91569a40c4512ea1b413e0c817d179ce9868
Author:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
AuthorDate: Sun, 18 Dec 2016 17:44:14 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 19 Dec 2016 10:46:20 +0100

x86/microcode/AMD: Use native_cpuid() in load_ucode_amd_bsp()

When CONFIG_PARAVIRT is selected, cpuid() becomes a call. Since
for 32-bit kernels load_ucode_amd_bsp() is executed before paging
is enabled the call cannot be completed (as kernel virtual addresses
are not reachable yet).

Use native_cpuid() instead which is an asm wrapper for the CPUID
instruction.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Jürgen Gross <jgross@...e.com>
Link: http://lkml.kernel.org/r/1481906392-3847-1-git-send-email-boris.ostrovsky@oracle.com
Link: http://lkml.kernel.org/r/20161218164414.9649-5-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/cpu/microcode/amd.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index dc80acf..6a31e26 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -301,6 +301,7 @@ static bool get_builtin_microcode(struct cpio_data *cp, unsigned int family)
 void __init load_ucode_amd_bsp(unsigned int family)
 {
 	struct ucode_cpu_info *uci;
+	u32 eax, ebx, ecx, edx;
 	struct cpio_data cp;
 	const char *path;
 	bool use_pa;
@@ -322,7 +323,10 @@ void __init load_ucode_amd_bsp(unsigned int family)
 		return;
 
 	/* Get BSP's CPUID.EAX(1), needed in load_microcode_amd() */
-	uci->cpu_sig.sig = cpuid_eax(1);
+	eax = 1;
+	ecx = 0;
+	native_cpuid(&eax, &ebx, &ecx, &edx);
+	uci->cpu_sig.sig = eax;
 
 	apply_microcode_early_amd(cp.data, cp.size, true, NULL);
 }