releases/4.9.102/x86-speculation-use-synthetic-bits-for-ibrs-ibpb-stibp.patch

From foo@baz Mon May 21 22:23:33 CEST 2018
From: Borislav Petkov <bp@suse.de>
Date: Wed, 2 May 2018 18:15:14 +0200
Subject: x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP

From: Borislav Petkov <bp@suse.de>

commit e7c587da125291db39ddf1f49b18e5970adbac17 upstream

Intel and AMD have different CPUID bits hence for those use synthetic bits
which get set on the respective vendor's in init_speculation_control(). So
that debacles like what the commit message of

  c65732e4f721 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")

talks about don't happen anymore.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Jörg Otte <jrg.otte@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20180504161815.GG9257@pd.tnic
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/cpufeatures.h |   12 ++++++++----
 arch/x86/kernel/cpu/common.c       |   14 ++++++++++----
 arch/x86/kvm/cpuid.c               |   10 +++++-----
 arch/x86/kvm/cpuid.h               |    4 ++--
 4 files changed, 25 insertions(+), 15 deletions(-)

--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -205,7 +205,10 @@
 #define X86_FEATURE_USE_IBPB	( 7*32+21) /* "" Indirect Branch Prediction Barrier enabled */
 #define X86_FEATURE_USE_IBRS_FW	( 7*32+22) /* "" Use IBRS during runtime firmware calls */
 #define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* "" Disable Speculative Store Bypass. */
-#define X86_FEATURE_AMD_SSBD	(7*32+24)  /* "" AMD SSBD implementation */
+#define X86_FEATURE_AMD_SSBD	( 7*32+24) /* "" AMD SSBD implementation */
+#define X86_FEATURE_IBRS	( 7*32+25) /* Indirect Branch Restricted Speculation */
+#define X86_FEATURE_IBPB	( 7*32+26) /* Indirect Branch Prediction Barrier */
+#define X86_FEATURE_STIBP	( 7*32+27) /* Single Thread Indirect Branch Predictors */
 
 /* Virtualization flags: Linux defined, word 8 */
 #define X86_FEATURE_TPR_SHADOW  ( 8*32+ 0) /* Intel TPR Shadow */
@@ -263,9 +266,9 @@
 /* AMD-defined CPU features, CPUID level 0x80000008 (ebx), word 13 */
 #define X86_FEATURE_CLZERO	(13*32+0) /* CLZERO instruction */
 #define X86_FEATURE_IRPERF	(13*32+1) /* Instructions Retired Count */
-#define X86_FEATURE_IBPB	(13*32+12) /* Indirect Branch Prediction Barrier */
-#define X86_FEATURE_IBRS	(13*32+14) /* Indirect Branch Restricted Speculation */
-#define X86_FEATURE_STIBP	(13*32+15) /* Single Thread Indirect Branch Predictors */
+#define X86_FEATURE_AMD_IBPB	(13*32+12) /* Indirect Branch Prediction Barrier */
+#define X86_FEATURE_AMD_IBRS	(13*32+14) /* Indirect Branch Restricted Speculation */
+#define X86_FEATURE_AMD_STIBP	(13*32+15) /* Single Thread Indirect Branch Predictors */
 
 /* Thermal and Power Management Leaf, CPUID level 0x00000006 (eax), word 14 */
 #define X86_FEATURE_DTHERM	(14*32+ 0) /* Digital Thermal Sensor */
@@ -301,6 +304,7 @@
 #define X86_FEATURE_SUCCOR	(17*32+1) /* Uncorrectable error containment and recovery */
 #define X86_FEATURE_SMCA	(17*32+3) /* Scalable MCA */
 
+
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (EDX), word 18 */
 #define X86_FEATURE_AVX512_4VNNIW	(18*32+ 2) /* AVX-512 Neural Network Instructions */
 #define X86_FEATURE_AVX512_4FMAPS	(18*32+ 3) /* AVX-512 Multiply Accumulation Single precision */
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -725,17 +725,23 @@ static void init_speculation_control(str
 	 * and they also have a different bit for STIBP support. Also,
 	 * a hypervisor might have set the individual AMD bits even on
 	 * Intel CPUs, for finer-grained selection of what's available.
-	 *
-	 * We use the AMD bits in 0x8000_0008 EBX as the generic hardware
-	 * features, which are visible in /proc/cpuinfo and used by the
-	 * kernel. So set those accordingly from the Intel bits.
 	 */
 	if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) {
 		set_cpu_cap(c, X86_FEATURE_IBRS);
 		set_cpu_cap(c, X86_FEATURE_IBPB);
 	}
+
 	if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
 		set_cpu_cap(c, X86_FEATURE_STIBP);
+
+	if (cpu_has(c, X86_FEATURE_AMD_IBRS))
+		set_cpu_cap(c, X86_FEATURE_IBRS);
+
+	if (cpu_has(c, X86_FEATURE_AMD_IBPB))
+		set_cpu_cap(c, X86_FEATURE_IBPB);
+
+	if (cpu_has(c, X86_FEATURE_AMD_STIBP))
+		set_cpu_cap(c, X86_FEATURE_STIBP);
 }
 
 void get_cpu_cap(struct cpuinfo_x86 *c)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -357,7 +357,7 @@ static inline int __do_cpuid_ent(struct
 
 	/* cpuid 0x80000008.ebx */
 	const u32 kvm_cpuid_8000_0008_ebx_x86_features =
-		F(IBPB) | F(IBRS);
+		F(AMD_IBPB) | F(AMD_IBRS);
 
 	/* cpuid 0xC0000001.edx */
 	const u32 kvm_cpuid_C000_0001_edx_x86_features =
@@ -619,10 +619,10 @@ static inline int __do_cpuid_ent(struct
 		entry->eax = g_phys_as | (virt_as << 8);
 		entry->edx = 0;
 		/* IBRS and IBPB aren't necessarily present in hardware cpuid */
-		if (boot_cpu_has(X86_FEATURE_IBPB))
-			entry->ebx |= F(IBPB);
-		if (boot_cpu_has(X86_FEATURE_IBRS))
-			entry->ebx |= F(IBRS);
+		if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
+			entry->ebx |= F(AMD_IBPB);
+		if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
+			entry->ebx |= F(AMD_IBRS);
 		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
 		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
 		break;
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -165,7 +165,7 @@ static inline bool guest_cpuid_has_ibpb(
 	struct kvm_cpuid_entry2 *best;
 
 	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
-	if (best && (best->ebx & bit(X86_FEATURE_IBPB)))
+	if (best && (best->ebx & bit(X86_FEATURE_AMD_IBPB)))
 		return true;
 	best = kvm_find_cpuid_entry(vcpu, 7, 0);
 	return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
@@ -176,7 +176,7 @@ static inline bool guest_cpuid_has_spec_
 	struct kvm_cpuid_entry2 *best;
 
 	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
-	if (best && (best->ebx & bit(X86_FEATURE_IBRS)))
+	if (best && (best->ebx & bit(X86_FEATURE_AMD_IBRS)))
 		return true;
 	best = kvm_find_cpuid_entry(vcpu, 7, 0);
 	return best && (best->edx & (bit(X86_FEATURE_SPEC_CTRL) | bit(X86_FEATURE_SSBD)));