48 lines
1.5 KiB
Diff
48 lines
1.5 KiB
Diff
From abfdcc849a720f36bbb075ee35d64e84314387fe Mon Sep 17 00:00:00 2001
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From: Borislav Petkov <bp@suse.de>
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Date: Wed, 25 May 2022 18:12:31 +0200
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Subject: [PATCH 06/36] x86/microcode: Taint and warn on late loading
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Warn before it is attempted and taint the kernel. Late loading microcode
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can lead to malfunction of the kernel when the microcode update changes
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behaviour. There is no way for the kernel to determine whether its safe or
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not.
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Signed-off-by: Borislav Petkov <bp@suse.de>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Link: https://lore.kernel.org/r/20220525161232.14924-4-bp@alien8.de
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(cherry picked from commit d23d33ea0fcdc4bbb484990bf53867f99c63ccab)
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Signed-off-by: Mridula Shastry <mridula.c.shastry@oracle.com>
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Reviewed-by: Todd Vierling <todd.vierling@oracle.com>
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---
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arch/x86/kernel/cpu/microcode/core.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
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index c4d19f4b7afb..a803b839b16e 100644
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--- a/arch/x86/kernel/cpu/microcode/core.c
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+++ b/arch/x86/kernel/cpu/microcode/core.c
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@@ -513,6 +513,9 @@ static int microcode_reload_late(void)
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{
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int ret;
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+ pr_err("Attempting late microcode loading - it is dangerous and taints the kernel.\n");
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+ pr_err("You should switch to early loading, if possible.\n");
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+
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atomic_set(&late_cpus_in, 0);
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atomic_set(&late_cpus_out, 0);
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@@ -561,6 +564,8 @@ put:
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if (ret >= 0)
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ret = size;
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+ add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
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+
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return ret;
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}
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--
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2.39.3
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