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From: Borislav Petkov <bp@alien8.de>
To: X86 ML <x86@kernel.org>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline
Date: Wed, 28 Feb 2018 11:28:43 +0100	[thread overview]
Message-ID: <20180228102846.13447-5-bp@alien8.de> (raw)
In-Reply-To: <20180228102846.13447-1-bp@alien8.de>

From: Ashok Raj <ashok.raj@intel.com>

Avoid loading microcode if any of the CPUs are offline, and issue a
warning. Having different microcode revisions on the system at any time
is outright dangerous.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/1519352533-15992-4-git-send-email-ashok.raj@intel.com
[ Massage it. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/cpu/microcode/core.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 63370651e376..fa32cb3dcca5 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -486,6 +486,16 @@ static void __exit microcode_dev_exit(void)
 /* fake device for request_firmware */
 static struct platform_device	*microcode_pdev;
 
+static int check_online_cpus(void)
+{
+	if (num_online_cpus() == num_present_cpus())
+		return 0;
+
+	pr_err("Not all CPUs online, aborting microcode update.\n");
+
+	return -EINVAL;
+}
+
 static enum ucode_state reload_for_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
@@ -519,7 +529,13 @@ static ssize_t reload_store(struct device *dev,
 		return size;
 
 	get_online_cpus();
+
+	ret = check_online_cpus();
+	if (ret)
+		goto put;
+
 	mutex_lock(&microcode_mutex);
+
 	for_each_online_cpu(cpu) {
 		tmp_ret = reload_for_cpu(cpu);
 		if (tmp_ret > UCODE_NFOUND) {
@@ -538,6 +554,8 @@ static ssize_t reload_store(struct device *dev,
 		microcode_check();
 
 	mutex_unlock(&microcode_mutex);
+
+put:
 	put_online_cpus();
 
 	if (!ret)
-- 
2.13.0

  parent reply	other threads:[~2018-02-28 10:31 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-28 10:28 [PATCH 0/7] x86/microcode: Improve late loading Borislav Petkov
2018-02-28 10:28 ` [PATCH 1/7] x86/microcode: Get rid of struct apply_microcode_ctx Borislav Petkov
2018-03-08  9:25   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 2/7] x86/microcode/intel: Check microcode revision before updating sibling threads Borislav Petkov
2018-03-08  9:25   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` [PATCH 3/7] x86/microcode/intel: Writeback and invalidate caches before updating microcode Borislav Petkov
2018-03-08  9:26   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` Borislav Petkov [this message]
2018-02-28 13:11   ` [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline Henrique de Moraes Holschuh
2018-02-28 13:26     ` Raj, Ashok
2018-02-28 19:07       ` Henrique de Moraes Holschuh
2018-03-05 22:06   ` Tom Lendacky
2018-03-08  9:26   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` [PATCH 5/7] x86/microcode/intel: Look into the patch cache first Borislav Petkov
2018-03-08  9:27   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 6/7] x86/microcode: Request microcode on the BSP Borislav Petkov
2018-03-05 22:08   ` Tom Lendacky
2018-03-08  9:27   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 7/7] x86/microcode: Synchronize late microcode loading Borislav Petkov
2018-02-28 13:59   ` Henrique de Moraes Holschuh
2018-02-28 14:08     ` Borislav Petkov
2018-02-28 17:48       ` Henrique de Moraes Holschuh
2018-03-05 22:09   ` Tom Lendacky
2018-03-08  9:28   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-03-05 22:12 ` [PATCH 0/7] x86/microcode: Improve late loading Tom Lendacky
2018-03-05 23:51   ` Raj, Ashok

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