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From: tip-bot for Borislav Petkov <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: arjan@linux.intel.com, dan.j.williams@intel.com,
	mingo@kernel.org, luto@kernel.org, bp@alien8.de,
	gregkh@linuxfoundation.org, hpa@zytor.com, dwmw2@infradead.org,
	linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
	ashok.raj@intel.com, dave.hansen@linux.intel.com, bp@suse.de,
	peterz@infradead.org, jpoimboe@redhat.com, tglx@linutronix.de
Subject: [tip:x86/pti] x86/CPU: Check CPU feature bits after microcode upgrade
Date: Sat, 17 Feb 2018 02:13:02 -0800	[thread overview]
Message-ID: <tip-42ca8082e260dcfd8afa2afa6ec1940b9d41724c@git.kernel.org> (raw)
In-Reply-To: <20180216112640.11554-4-bp@alien8.de>

Commit-ID:  42ca8082e260dcfd8afa2afa6ec1940b9d41724c
Gitweb:     https://git.kernel.org/tip/42ca8082e260dcfd8afa2afa6ec1940b9d41724c
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Fri, 16 Feb 2018 12:26:40 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 17 Feb 2018 08:43:55 +0100

x86/CPU: Check CPU feature bits after microcode upgrade

With some microcode upgrades, new CPUID features can become visible on
the CPU. Check what the kernel has mirrored now and issue a warning
hinting at possible things the user/admin can do to make use of the
newly visible features.

Originally-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180216112640.11554-4-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/cpu/common.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 84f1cd8..348cf48 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1757,5 +1757,25 @@ core_initcall(init_cpu_syscore);
  */
 void microcode_check(void)
 {
+	struct cpuinfo_x86 info;
+
 	perf_check_microcode();
+
+	/* Reload CPUID max function as it might've changed. */
+	info.cpuid_level = cpuid_eax(0);
+
+	/*
+	 * Copy all capability leafs to pick up the synthetic ones so that
+	 * memcmp() below doesn't fail on that. The ones coming from CPUID will
+	 * get overwritten in get_cpu_cap().
+	 */
+	memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+
+	get_cpu_cap(&info);
+
+	if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
+		return;
+
+	pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
+	pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
 }

      reply	other threads:[~2018-02-17 10:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-16 11:26 [PATCH 0/3] x86/microcode: Add a microcode loader callback Borislav Petkov
2018-02-16 11:26 ` [PATCH 1/3] x86/microcode: Propagate return value from updating functions Borislav Petkov
2018-02-17 10:12   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-16 11:26 ` [PATCH 2/3] x86/CPU: Add a microcode loader callback Borislav Petkov
2018-02-17 10:12   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-17 13:07   ` [PATCH 2/3] " Raj, Ashok
2018-02-17 13:28     ` Borislav Petkov
2018-02-17 17:06       ` Raj, Ashok
2018-02-16 11:26 ` [PATCH 3/3] x86/CPU: Check CPU feature bits after microcode upgrade Borislav Petkov
2018-02-17 10:13   ` tip-bot for Borislav Petkov [this message]

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