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From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 6/6] x86/microcode/amd: Do not overwrite final patch levels
Date: Mon, 12 Oct 2015 11:22:42 +0200	[thread overview]
Message-ID: <1444641762-9437-7-git-send-email-bp@alien8.de> (raw)
In-Reply-To: <1444641762-9437-1-git-send-email-bp@alien8.de>

From: Borislav Petkov <bp@suse.de>

A certain number of patch levels of applied microcode should not be
overwritten by the microcode loader, otherwise bad things will happen.

Check those and abort update if the current core has one of those final
patch levels applied by the BIOS. 32-bit needs special handling, of
course.

See https://bugzilla.suse.com/show_bug.cgi?id=913996 for more info.

Tested-by: Peter Kirchgeßner <pkirchgessner@t-online.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/include/asm/microcode_amd.h      |  2 +-
 arch/x86/kernel/cpu/microcode/amd.c       | 38 +++++++++++++++++++++++++++----
 arch/x86/kernel/cpu/microcode/amd_early.c | 13 ++++++++---
 3 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/microcode_amd.h b/arch/x86/include/asm/microcode_amd.h
index 9b214e10d499..d3e86cfd08fe 100644
--- a/arch/x86/include/asm/microcode_amd.h
+++ b/arch/x86/include/asm/microcode_amd.h
@@ -76,5 +76,5 @@ static inline int __init save_microcode_in_initrd_amd(void) { return -EINVAL; }
 void reload_ucode_amd(void) {}
 #endif
 
-extern bool check_current_patch_level(u32 *rev);
+extern bool check_current_patch_level(u32 *rev, bool early);
 #endif /* _ASM_X86_MICROCODE_AMD_H */
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 2d630138bf3e..da922d1e2f71 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -178,6 +178,16 @@ static unsigned int verify_patch_size(u8 family, u32 patch_size,
 }
 
 /*
+ * Those patch levels cannot be updated to newer ones and thus should be final.
+ */
+static u32 final_levels[] = {
+	0x01000098,
+	0x0100009f,
+	0x010000af,
+	0, /* T-101 terminator */
+};
+
+/*
  * 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
@@ -187,13 +197,31 @@ static unsigned int verify_patch_size(u8 family, u32 patch_size,
  *  - true: if update should stop
  *  - false: otherwise
  */
-bool check_current_patch_level(u32 *rev)
+bool check_current_patch_level(u32 *rev, bool early)
 {
-	u32 dummy;
+	u32 lvl, dummy, i;
+	bool ret = false;
+	u32 *levels;
+
+	native_rdmsr(MSR_AMD64_PATCH_LEVEL, lvl, dummy);
+
+	if (IS_ENABLED(CONFIG_X86_32) && early)
+		levels = (u32 *)__pa_nodebug(&final_levels);
+	else
+		levels = final_levels;
+
+	for (i = 0; levels[i]; i++) {
+		if (lvl == levels[i]) {
+			lvl = 0;
+			ret = true;
+			break;
+		}
+	}
 
-	native_rdmsr(MSR_AMD64_PATCH_LEVEL, *rev, dummy);
+	if (rev)
+		*rev = lvl;
 
-	return false;
+	return ret;
 }
 
 int __apply_microcode_amd(struct microcode_amd *mc_amd)
@@ -229,7 +257,7 @@ int apply_microcode_amd(int cpu)
 	mc_amd  = p->data;
 	uci->mc = p->data;
 
-	if (check_current_patch_level(&rev))
+	if (check_current_patch_level(&rev, false))
 		return -1;
 
 	/* need to apply patch? */
diff --git a/arch/x86/kernel/cpu/microcode/amd_early.c b/arch/x86/kernel/cpu/microcode/amd_early.c
index abb90097582f..a54a47b9d8ea 100644
--- a/arch/x86/kernel/cpu/microcode/amd_early.c
+++ b/arch/x86/kernel/cpu/microcode/amd_early.c
@@ -196,7 +196,7 @@ static void apply_ucode_in_initrd(void *ucode, size_t size, bool save_patch)
 		return;
 	}
 
-	if (check_current_patch_level(&rev))
+	if (check_current_patch_level(&rev, true))
 		return;
 
 	while (left > 0) {
@@ -330,7 +330,10 @@ void load_ucode_amd_ap(void)
 	if (!container)
 		return;
 
-	if (check_current_patch_level(&rev))
+	/*
+	 * 64-bit runs with paging enabled, thus early==false.
+	 */
+	if (check_current_patch_level(&rev, false))
 		return;
 
 	eax = cpuid_eax(0x00000001);
@@ -422,7 +425,11 @@ void reload_ucode_amd(void)
 	struct microcode_amd *mc;
 	u32 rev;
 
-	if (check_current_patch_level(&rev))
+	/*
+	 * early==false because this is a syscore ->resume path and by
+	 * that time paging is long enabled.
+	 */
+	if (check_current_patch_level(&rev, false))
 		return;
 
 	mc = (struct microcode_amd *)amd_ucode_patch;
-- 
2.3.5


  parent reply	other threads:[~2015-10-12  9:23 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-12  9:22 [PATCH 0/6] tip-queue 2015-10-12 Borislav Petkov
2015-10-12  9:22 ` [PATCH 1/6] x86/mce: Don't clear shared banks on Intel when offlining CPUs Borislav Petkov
2015-10-12  9:22 ` [PATCH 2/6] x86/ras/mce_amd_inj: Return early on invalid input Borislav Petkov
2015-10-12 14:31   ` [tip:ras/core] " tip-bot for Aravind Gopalakrishnan
2015-10-12  9:22 ` [PATCH 3/6] x86/ras/mce_amd_inj: Trigger deferred and thresholding errors interrupts Borislav Petkov
2015-10-12 14:31   ` [tip:ras/core] " tip-bot for Aravind Gopalakrishnan
2015-10-12  9:22 ` [PATCH 4/6] x86/ras/mce_amd_inj: Inject bank 4 errors on the NBC Borislav Petkov
2015-10-12 14:31   ` [tip:ras/core] " tip-bot for Aravind Gopalakrishnan
2015-10-12  9:22 ` [PATCH 5/6] x86/microcode/amd: Extract current patch level read to a function Borislav Petkov
2015-10-12 14:32   ` [tip:ras/core] " tip-bot for Borislav Petkov
2015-10-12  9:22 ` Borislav Petkov [this message]
2015-10-12 14:32   ` [tip:ras/core] x86/microcode/amd: Do not overwrite final patch levels tip-bot for Borislav Petkov
  -- strict thread matches above, loose matches on Subject: below --
2015-09-25 14:20 [PATCH V2 0/3] Updates to mce_amd_inj module Aravind Gopalakrishnan
2015-09-25 14:20 ` [PATCH V2 1/3] RAS, mce_amd_inj: Return early on invalid input Aravind Gopalakrishnan
2015-09-25 14:20 ` [PATCH V2 2/3] RAS, mce_amd_inj: Add capability to trigger apic interrupts Aravind Gopalakrishnan
2015-09-25 14:20 ` [PATCH V2 3/3] RAS, mce_amd_inj: Inject errors on NBC for bank 4 errors Aravind Gopalakrishnan
2015-09-28  9:06 ` [PATCH V2 0/3] Updates to mce_amd_inj module Borislav Petkov

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