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  3.   31-x86-speculation-use-synthetic-bits-for-ibrs-ibpb-stibp.patch
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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
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Git-commit: e7c587da125291db39ddf1f49b18e5970adbac17
Patch-mainline: v4.17-rc7
References: bsc#1087082 CVE-2018-3639

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
---
 arch/x86/include/asm/cpufeatures.h |   11 ++++++-----
 arch/x86/kernel/cpu/common.c       |   14 ++++++++++----
 arch/x86/kvm/cpuid.c               |   10 +++++-----
 arch/x86/kvm/svm.c                 |    6 +++---
 arch/x86/kvm/vmx.c                 |    9 ++-------
 5 files changed, 26 insertions(+), 24 deletions(-)

--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -199,7 +199,6 @@
 #define X86_FEATURE_CAT_L2	( 7*32+ 5) /* Cache Allocation Technology L2 */
 #define X86_FEATURE_CDP_L3	( 7*32+ 6) /* Code and Data Prioritization L3 */
 #define X86_FEATURE_INVPCID_SINGLE	( 7*32+ 7) /* Effectively INVPCID && CR4.PCIDE=1 */
-
 #define X86_FEATURE_HW_PSTATE	( 7*32+ 8) /* AMD HW-PState */
 #define X86_FEATURE_PROC_FEEDBACK ( 7*32+ 9) /* AMD ProcFeedbackInterface */
 #define X86_FEATURE_SME		( 7*32+10) /* AMD Secure Memory Encryption */
@@ -212,11 +211,13 @@
 #define X86_FEATURE_MBA         ( 7*32+18) /* Memory Bandwidth Allocation */
 #define X86_FEATURE_RSB_CTXSW		( 7*32+19) /* "" Fill RSB on context switches */
 #define X86_FEATURE_SEV			( 7*32+20) /* AMD Secure Encrypted Virtualization */
-
 #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+24) /* "" Disable Speculative Store Bypass. */
 #define X86_FEATURE_AMD_SSBD		(7*32+25)  /* "" AMD SSBD implementation */
+#define X86_FEATURE_IBRS		( 7*32+26) /* Indirect Branch Restricted Speculation */
+#define X86_FEATURE_IBPB		( 7*32+27) /* Indirect Branch Prediction Barrier */
+#define X86_FEATURE_STIBP		( 7*32+28) /* Single Thread Indirect Branch Predictors */
 
 /* Virtualization flags: Linux defined, word 8 */
 #define X86_FEATURE_TPR_SHADOW  ( 8*32+ 0) /* Intel TPR Shadow */
@@ -277,9 +278,9 @@
 #define X86_FEATURE_CLZERO	(13*32+0) /* CLZERO instruction */
 #define X86_FEATURE_IRPERF	(13*32+1) /* Instructions Retired Count */
 #define X86_FEATURE_XSAVEERPTR		(13*32+ 2) /* Always save/restore FP error pointers */
-#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 */
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -733,17 +733,23 @@ 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
@@ -367,7 +367,7 @@ 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 =
@@ -632,10 +632,10 @@ 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/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4055,7 +4055,7 @@ static int svm_get_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBRS))
+		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS))
 			return 1;
 
 		msr_info->data = svm->spec_ctrl;
@@ -4156,7 +4156,7 @@ static int svm_set_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBRS))
+		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS))
 			return 1;
 
 		/* The STIBP bit doesn't fault even if it's not advertised */
@@ -4183,7 +4183,7 @@ static int svm_set_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_PRED_CMD:
 		if (!msr->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBPB))
+		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB))
 			return 1;
 
 		if (data & ~PRED_CMD_IBPB)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3294,9 +3294,7 @@ static int vmx_get_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBRS) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SSBD))
+		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
 			return 1;
 
 		msr_info->data = to_vmx(vcpu)->spec_ctrl;
@@ -3416,9 +3414,7 @@ static int vmx_set_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBRS) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SSBD))
+		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
 			return 1;
 
 		/* The STIBP bit doesn't fault even if it's not advertised */
@@ -3448,7 +3444,6 @@ static int vmx_set_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_PRED_CMD:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_IBPB) &&
 		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
 			return 1;
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