Date:   Tue, 25 Apr 2017 13:45:41 +0200
From:   Denys Vlasenko <dvlasenk@...hat.com>
To:     Ingo Molnar <mingo@...hat.com>
Cc:     Denys Vlasenko <dvlasenk@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "H. Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86, msr: Better document AMD "tweak MSRs", rename MSR_F15H_IC_CFG

Before this patch, we have a define for MSR 0xc0011021: MSR_F15H_IC_CFG.
But it exists starting from K8, so it's not really a Fam15h MSR only.

Lat's call it MSR_AMD64_IC_CFG.

In fact, there is a whole bunch of similar "CFG" registers in this range,
and they are rather sparsely documented by AMD.

Let's have a comment about that.

MSRs in 0xC001102x range (and a few close to this range)
allow to modify some internal actions of the pipeline.
(There is one non-debug MSR in this range, introduced in Fam15h:
MSR 0xC0011027 Address Mask For DR0 Breakpoints, aka DR0_ADDR_MASK).

Sometimes these MSRs are used to fix erratas. Here is a little
compilation from about a dozen documents.

C001_1000:
15h Errata 608 "P-state Limit Changes May Not Generate Interrupts"
	- worked around by setting bit 16.
15h Errata 671 "Debug Breakpoint on Misaligned Store May Cause System Hang"
	- worked around by setting bit 17 to 0.
	- AMD is really reluctant to this workaround, must be painful
15h Errata 727 "Processor Core May Hang During CC6 Resume"
	- worked around by setting bit 15.
	- HW fixed in models 10h?

C001_1020:
K8 Errata 106
"Potential Deadlock with Tightly Coupled Semaphores in an MP System"
	- worked around by setting bit 25.
10h,12h Errata 670
"Segment Load May Cause System Hang or Fault After State Change"
	- worked around by setting bit 8.
	- this bit has something to do with handling of LOCK prefix.
14h Errata 530
"Potential Violation of Read Ordering Rules Between Semaphore Operation
and Subsequent Load Operations"
	- worked around by setting bit 36.
14h Errata 551
"Processor May Not Forward Data From Store to a Page Crossing
Read-Modify-Write Operation"
	- worked around by setting bit 25.
14h Errata 560
"Processor May Incorrectly Forward Data with Non-cacheable Floating-Point
128-bit SSE Operation"
	-  worked around by setting bit 18.
16h Errata 793
"Specific Combination of Writes to Write Combined Memory Types and Locked
Instructions May Cause Core Hang"
	- worked around by setting bit 15.

C001_1021:
K8 Errata 94
"Sequential Prefetch Feature May Cause Incorrect Processor Operation"
	- worked around by setting bit 11.
14h Errata 688
"Processor May Cause Unpredictable Program Behavior Under Highly Specific
Branch Conditions"
	- worked around by setting bits 14 and 3.
16h Errata 776
"Incorrect Processor Branch Prediction for Two Consecutive Linear Pages"
	- worked around by setting bit 26.
	- HW fixed in models 30h?

C001_1022:
K8 Errata 97 "128-Bit Streaming Stores May Cause Coherency Failure"
	- worked around by setting bit 3.
K8 Errata 81
"Cache Coherency Problem with Hardware Prefetching and Streaming Stores"
	- worked around by setting bit 10.
10h Errata 261
"Processor May Stall Entering Stop-Grant Due to Pending Data Cache Scrub"
	- worked around by setting bit 24.
10h Errata 326 "Misaligned Load Operation May Cause Processor Core Hang"
	- worked around by setting bits 43:42 to 00.
10h Errata 383
"CPU Core May Machine Check When System Software Changes Page Tables
Dynamically"
	- worked around by setting bit 47.
15h Errata 674
"Processor May Cache Prefetched Data from Remapped Memory Region"
	- worked around by setting bit 13.

C001_1023:
K8 Errata 69
"Multiprocessor Coherency Problem with Hardware Prefetch Mechanism"
	- worked around by setting bit 45.
K8 Errata 113 "Enhanced Write-Combining Feature Causes System Hang"
	- worked around by setting bit 48.
10h Errata 254 "Internal Resource Livelock Involving Cached TLB Reload"
	- worked around by setting bit 21.
10h Errata 298
"L2 Eviction May Occur During Processor Operation To Set Accessed or Dirty Bit"
	- worked around by setting bit 1.
10h Errata 309
"Processor Core May Execute Incorrect Instructions on Concurrent L2 and
Northbridge Response"
	- worked around by setting bit 23.

C001_1029:
10h,12h Errata 721 "Processor May Incorrectly Update Stack Pointer"
	- worked around by setting bit 0.
12h Errata 665 "Integer Divide Instruction May Cause Unpredictable Behavior"
	- worked around by setting bit 31.
Bit 23 serializes CLFLUSH instruction.

C001_102A:
15h Errata 503 "APIC Task-Priority Register May Be Incorrect"
	- worked around by setting bit 11.

K8_BKDG documents none of these registers, but Revision Guide mentions them a lot.

10h_BKDG documents them as:
MSRC001_1021 Instruction Cache Configuration Register (IC_CFG)
MSRC001_1022 Data Cache Configuration (DC_CFG)
MSRC001_1023 Bus Unit Configuration Register (BU_CFG)
MSRC001_102A Bus Unit Configuration 2 (BU_CFG2)

11h_BKDG documents:
MSRC001_1022 Data Cache Configuration (DC_CFG)
MSRC001_1023 Bus Unit Configuration Register (BU_CFG)

12h_BKDG documents:
MSRC001_1020 Load-Store Configuration (LS_CFG)
MSRC001_1021 Instruction Cache Configuration (IC_CFG)
MSRC001_1022 Data Cache Configuration (DC_CFG)
MSRC001_1029 Decode Configuration (DE_CFG)
MSRC001_102A Combined Unit Configuration 2 (CU_CFG2) - name change since 10h

14h_Mod_00h-0Fh_BKDG documents only:
MSRC001_1020 Load-Store Configuration (LS_CFG)
MSRC001_1021 Instruction Cache Configuration (IC_CFG)
MSRC001_1022 Data Cache Configuration (DC_CFG)

15h_Mod_00h-0Fh_BKDG documents more:
MSRC001_1020 Load-Store Configuration (LS_CFG)
MSRC001_1021 Instruction Cache Configuration (IC_CFG)
MSRC001_1022 Data Cache Configuration (DC_CFG)
MSRC001_1023 Combined Unit Configuration (CU_CFG) - name change since 11h
MSRC001_1028 Floating Point Configuration (FP_CFG)
MSRC001_1029 Decode Configuration (DE_CFG)
MSRC001_102A Combined Unit Configuration 2 (CU_CFG2)
MSRC001_102B Combined Unit Configuration 3 (CU_CFG3)
MSRC001_102C Execution Unit Configuration (EX_CFG)
MSRC001_102D Load-Store Configuration 2 (LS_CFG2)

15h_Mod_10h-1Fh_BKDG: does not mention MSRC001_1029 and MSRC001_102C.

15h_Mod_30h-3Fh_BKDG: does not mention MSRC001_1029, MSRC001_102C
and MSRC001_102D, adds new one:
MSRC001_102F Prefetch Throttling Configuration (CU_PFTCFG)

15h_Mod_60h-6Fh_BKDG: also fails to mention MSRC001_1029, MSRC001_102C
and MSRC001_102D, but has new ones:
MSRC001_101C Load-Store Configuration 3 (LS_CFG3)
MSRC001_1090 Processor Feedback Constants 0
MSRC001_10A1 Contention Blocking Buffer Control (CU_CBBCFG)

16h_Mod_00h-0Fh_BKDG: stuff disappeared or got renamed
(1023 and 102A are "Bus Unit Configuration" again):
MSRC001_1020 Load-Store Configuration (LS_CFG)
MSRC001_1021 Instruction Cache Configuration (IC_CFG)
MSRC001_1022 Data Cache Configuration (DC_CFG)
MSRC001_1023 Bus Unit Configuration (BU_CFG)
MSRC001_1028 Floating Point Configuration (FP_CFG) - all bits are "reserved"
MSRC001_102A Bus Unit Configuration 2 (BU_CFG2)

16h_Mod_30h-3Fh_BKDG: FP_CFG now has one documented field

CC: Ingo Molnar <mingo@...hat.com>
CC: Andy Lutomirski <luto@...nel.org>
CC: Borislav Petkov <bp@...en8.de>
CC: Brian Gerst <brgerst@...il.com>
CC: Peter Zijlstra <peterz@...radead.org>
CC: "H. Peter Anvin" <hpa@...ux.intel.com>
CC: x86@...nel.org
CC: linux-kernel@...r.kernel.org
Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
---
 arch/x86/include/asm/msr-index.h | 20 +++++++++++++++++++-
 arch/x86/kernel/cpu/amd.c        |  4 ++--
 arch/x86/kvm/svm.c               |  2 +-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index d8b5f8a..4195681 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -293,9 +293,28 @@
 #define MSR_AMD64_PATCH_LOADER		0xc0010020
 #define MSR_AMD64_OSVW_ID_LENGTH	0xc0010140
 #define MSR_AMD64_OSVW_STATUS		0xc0010141
+/*
+ * MSRs in 0xc001101c-0xc001102f range are sparsely documented in BKDGs,
+ * but sometimes they can be found in errata documents.
+ * Registers 1020..1023 exist since K8. Fam10h and later have regs 1028..102d.
+ * Fam15h BKDGs document registers 102f, 101c, 1090, 10a1.
+ * Registers 1023 and 102a are called "Combined Unit Cfg" in Fam12h-15h,
+ * but "Bus Unit Cfg" in K8, Fam10h, 11h and 16h. Other "CU_" registers
+ * might also be "BU_" (did not find them in docs for these families).
+ */
+#define MSR_AMD64_LS_CFG3		0xc001101c
 #define MSR_AMD64_LS_CFG		0xc0011020
+#define MSR_AMD64_IC_CFG		0xc0011021
 #define MSR_AMD64_DC_CFG		0xc0011022
+#define MSR_AMD64_BU_CFG		0xc0011023
+#define MSR_AMD64_FP_CFG 		0xc0011028
+#define MSR_AMD64_DE_CFG 		0xc0011029
 #define MSR_AMD64_BU_CFG2		0xc001102a
+#define MSR_AMD64_CU_CFG3		0xc001102b
+#define MSR_AMD64_EX_CFG 		0xc001102c
+#define MSR_AMD64_LS_CFG2		0xc001102d
+#define MSR_AMD64_CU_PFTCFG		0xc001102f
+
 #define MSR_AMD64_IBSFETCHCTL		0xc0011030
 #define MSR_AMD64_IBSFETCHLINAD		0xc0011031
 #define MSR_AMD64_IBSFETCHPHYSAD	0xc0011032
@@ -332,7 +351,6 @@
 #define MSR_F15H_NB_PERF_CTL		0xc0010240
 #define MSR_F15H_NB_PERF_CTR		0xc0010241
 #define MSR_F15H_PTSC			0xc0010280
-#define MSR_F15H_IC_CFG			0xc0011021
 
 /* Fam 10h MSRs */
 #define MSR_FAM10H_MMIO_CONF_BASE	0xc0010058
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index c36140d..7d4a5bf 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -720,9 +720,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
 	 * Disable it on the affected CPUs.
 	 */
 	if ((c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
-		if (!rdmsrl_safe(MSR_F15H_IC_CFG, &value) && !(value & 0x1E)) {
+		if (!rdmsrl_safe(MSR_AMD64_IC_CFG, &value) && !(value & 0x1E)) {
 			value |= 0x1E;
-			wrmsrl_safe(MSR_F15H_IC_CFG, value);
+			wrmsrl_safe(MSR_AMD64_IC_CFG, value);
 		}
 	}
 }
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 5fba706..1e0b19e 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3476,7 +3476,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_UCODE_REV:
 		msr_info->data = 0x01000065;
 		break;
-	case MSR_F15H_IC_CFG: {
+	case MSR_AMD64_IC_CFG: {
 
 		int family, model;
 
-- 
2.9.2

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