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x86/microcode/intel: Clear patch pointer before jettisoning the initrd

PATCH New Borislav Petkov 2 participants 2 messages Jun 7, 2017 – Jun 8, 2017

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x86 x86 microcode update support
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Borislav Petkov

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PATCH 1/1 x86/microcode/intel: Clear patch pointer before jettisoning the initrd

From: Dominik Brodowski <[email protected]>

During early boot, load_ucode_intel_ap() uses __load_ucode_intel() to obtain a pointer to the relevant microcode patch (embedded in the initrd), and stores this value in intel_ucode_patch to speed up the microcode patch application for subsequent CPUs.

On resuming from suspend-to-RAM, however, load_ucode_ap() calls load_ucode_intel_ap() for each non-boot-CPU. By then the initramfs is long gone so the pointer stored in intel_ucode_patch no longer points to a valid microcode patch.

Clear that pointer so that we effectively fallback to the CPU hotplug notifier callbacks to update the microcode.

Signed-off-by Dominik Brodowski <[email protected]>
Cc <[email protected]> # 4.10..
[ Edit and massage commit message. ]
Signed-off-by Borislav Petkov <[email protected]>
---
 arch/x86/kernel/cpu/microcode/intel.c | 3 +++
 1 file changed, 3 insertions(+)
arch/x86/kernel/cpu/microcode/intel.c +3 -0
index afdfd237b59f..f522415bf9e5 100644
@@ -619,6 +619,9 @@ int __init save_microcode_in_initrd_intel(void)
 
 	show_saved_mc();
 
+	/* initrd is going away, clear patch ptr. */
+	intel_ucode_patch = NULL;
+
 	return 0;
 }
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2.13.0
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#1 lore raw
x86/microcode/intel: Clear patch pointer before jettisoning the initrd
Commit-ID:  5b0bc9ac2ce4881ee318a21f31140584ce4dbdad
Gitweb:     http://git.kernel.org/tip/5b0bc9ac2ce4881ee318a21f31140584ce4dbdad
Author:     Dominik Brodowski <[email protected]>
AuthorDate: Wed, 7 Jun 2017 11:58:19 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 8 Jun 2017 10:03:05 +0200

x86/microcode/intel: Clear patch pointer before jettisoning the initrd

During early boot, load_ucode_intel_ap() uses __load_ucode_intel() to obtain a pointer to the relevant microcode patch (embedded in the initrd), and stores this value in 'intel_ucode_patch' to speed up the microcode patch application for subsequent CPUs.

On resuming from suspend-to-RAM, however, load_ucode_ap() calls load_ucode_intel_ap() for each non-boot-CPU. By then the initramfs is long gone so the pointer stored in 'intel_ucode_patch' no longer points to a valid microcode patch.

Clear that pointer so that we effectively fall back to the CPU hotplug notifier callbacks to update the microcode.

Signed-off-by Dominik Brodowski <[email protected]>
[ Edit and massage commit message. ]
Signed-off-by Borislav Petkov <[email protected]>
Cc <[email protected]> # 4.10..
Cc Linus Torvalds <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 arch/x86/kernel/cpu/microcode/intel.c | 3 +++
 1 file changed, 3 insertions(+)
arch/x86/kernel/cpu/microcode/intel.c +3 -0
index afdfd23..f522415 100644
@@ -619,6 +619,9 @@ int __init save_microcode_in_initrd_intel(void)
 
 	show_saved_mc();
 
+	/* initrd is going away, clear patch ptr. */
+	intel_ucode_patch = NULL;
+
 	return 0;
 }