linux-kernel - [PATCH 3.2 03/46] x86/microcode/amd: Extract current patch level read to a function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1465767281.462780722@decadent.org.uk>
Date:	Sun, 12 Jun 2016 22:34:41 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Ingo Molnar" <mingo@...nel.org>, "Borislav Petkov" <bp@...en8.de>,
	"Borislav Petkov" <bp@...e.de>, "H. Peter Anvin" <hpa@...or.com>,
	"Henrique de Moraes Holschuh" <hmh@....eng.br>,
	"Peter Zijlstra" <peterz@...radead.org>,
	"Takashi Iwai" <tiwai@...e.com>, "Tony Luck" <tony.luck@...el.com>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.2 03/46] x86/microcode/amd: Extract current patch level
 read to a  function

3.2.81-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Borislav Petkov <bp@...e.de>

commit 2eff73c0a11f19ff082a566e3429fbaaca7b8e7b upstream.

Pave the way for checking the current patch level of the
microcode in a core. We want to be able to do stuff depending on
the patch level - in this case decide whether to update or not.
But that will be added in a later patch.

Drop unused local var uci assignment, while at it.

Integrate a fix for 32-bit and CONFIG_PARAVIRT from Takashi Iwai:

 Use native_rdmsr() in check_current_patch_level() because with
 CONFIG_PARAVIRT enabled and on 32-bit, where we run before
 paging has been enabled, we cannot deref pv_info yet. Or we
 could, but we'd need to access its physical address. This way of
 fixing it is simpler. See:

   https://bugzilla.suse.com/show_bug.cgi?id=943179 for the background.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Takashi Iwai <tiwai@...e.com>:
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>
Link: http://lkml.kernel.org/r/1444641762-9437-6-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Henrique de Moraes Holschuh <hmh@....eng.br>
---
 arch/x86/include/asm/microcode.h      |  1 +
 arch/x86/kernel/microcode_amd.c       | 24 ++++++++++++++++++++++--
 3 files changed, 30 insertions(+), 12 deletions(-)

--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -61,4 +61,5 @@ static inline struct microcode_ops * __i
 }
 #endif
 
+extern bool check_current_patch_level(u32 *rev);
 #endif /* _ASM_X86_MICROCODE_H */
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -123,13 +123,32 @@ static int get_matching_microcode(int cp
 	return 1;
 }
 
+/*
+ * Check the current patch level on this CPU.
+ *
+ * @rev: Use it to return the patch level. It is set to 0 in the case of
+ * error.
+ *
+ * Returns:
+ *  - true: if update should stop
+ *  - false: otherwise
+ */
+bool check_current_patch_level(u32 *rev)
+{
+	u32 dummy;
+
+	rdmsr(MSR_AMD64_PATCH_LEVEL, *rev, dummy);
+
+	return false;
+}
+
 static int apply_microcode_amd(int cpu)
 {
-	u32 rev, dummy;
 	int cpu_num = raw_smp_processor_id();
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
 	struct microcode_amd *mc_amd = uci->mc;
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
+	u32 dummy, rev;
 
 	/* We should bind the task to the CPU */
 	BUG_ON(cpu_num != cpu);
@@ -137,6 +156,9 @@ static int apply_microcode_amd(int cpu)
 	if (mc_amd == NULL)
 		return 0;
 
+	if (check_current_patch_level(&rev))
+		return -1;
+
 	wrmsrl(MSR_AMD64_PATCH_LOADER, (u64)(long)&mc_amd->hdr.data_code);
 	/* get patch id after patching */
 	rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);