From: Borislav Petkov <bp@alien8.de>
To: "Jörg Otte" <jrg.otte@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre_v2 mitigation.
Date: Fri, 4 May 2018 18:18:15 +0200 [thread overview]
Message-ID: <20180504161815.GG9257@pd.tnic> (raw)
In-Reply-To: <alpine.DEB.2.21.1805021418550.1560@nanos.tec.linutronix.de>
On Wed, May 02, 2018 at 02:20:52PM +0200, Thomas Gleixner wrote:
> Thanks for confirming. Still need to find a way which is less fragile, but
> that's probably too much of churn for rc4....
>
> At least I know exactly what's happening, so I can write a better changelog.
>
> Thanks for testing!
Jörg, can you pls also test this one ontop of Thomas' patch to make
sure it doesn't break your box.
Thx.
---
>From 6857c2ac8e31f4f9b350cfad4f6b6eb831bf57f1 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Wed, 2 May 2018 18:15:14 +0200
Subject: [PATCH] x86/CPU: Use synthetic bits for IBRS/IBPB/STIBP
Intel and AMD have different CPUID bits for those so use synthetic bits
which get set on the respective vendor in init_speculation_control(). So
that debacles like 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>
---
arch/x86/include/asm/cpufeatures.h | 12 ++++++------
arch/x86/kernel/cpu/common.c | 14 ++++++++++----
arch/x86/kvm/svm.c | 6 +++---
arch/x86/kvm/vmx.c | 3 ---
4 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 578793e97431..0482da6d7d6f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -198,7 +198,6 @@
#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 */
@@ -207,13 +206,14 @@
#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */
#define X86_FEATURE_INTEL_PPIN ( 7*32+14) /* Intel Processor Inventory Number */
#define X86_FEATURE_CDP_L2 ( 7*32+15) /* Code and Data Prioritization L2 */
-
+#define X86_FEATURE_IBRS ( 7*32+16) /* Indirect Branch Restricted Speculation */
+#define X86_FEATURE_IBPB ( 7*32+17) /* Indirect Branch Prediction Barrier */
#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_STIBP ( 7*32+23) /* Single Thread Indirect Branch Predictors */
/* Virtualization flags: Linux defined, word 8 */
#define X86_FEATURE_TPR_SHADOW ( 8*32+ 0) /* Intel TPR Shadow */
@@ -274,9 +274,9 @@
#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 */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index ce243f7d2d4e..1831203800d3 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -757,17 +757,23 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
* 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)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1fc05e428aba..71e1d6334f7d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4108,7 +4108,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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;
@@ -4203,7 +4203,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
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 */
@@ -4230,7 +4230,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
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)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c7668806163f..dca7e8b8597b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3523,7 +3523,6 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return kvm_get_msr_common(vcpu, msr_info);
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))
return 1;
@@ -3642,7 +3641,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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))
return 1;
@@ -3673,7 +3671,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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;
--
2.17.0.391.g1f1cddd558b5
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-05-04 16:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-30 15:59 [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre_v2 mitigation Jörg Otte
2018-04-30 19:53 ` Thomas Gleixner
2018-05-01 7:39 ` Jörg Otte
2018-05-01 12:59 ` Thomas Gleixner
2018-05-01 18:27 ` Thomas Gleixner
2018-05-01 23:07 ` Tim Chen
2018-05-01 20:14 ` Linus Torvalds
2018-05-02 7:43 ` Jörg Otte
2018-05-02 9:02 ` Thomas Gleixner
2018-05-02 9:25 ` Jörg Otte
2018-05-02 12:20 ` Thomas Gleixner
2018-05-04 16:18 ` Borislav Petkov [this message]
2018-05-05 9:47 ` Jörg Otte
2018-05-05 9:53 ` Borislav Petkov
2018-05-02 14:48 ` [tip:x86/urgent] x86/cpu: Restore CPUID_8000_0008_EBX reload tip-bot for Thomas Gleixner
2018-05-02 18:08 ` Tim Chen
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