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Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 pti updates from Thomas Gleixner:
 "Three small commits updating the SSB mitigation to take the updated
  AMD mitigation variants into account"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/bugs: Switch the selection of mitigation from CPU vendor to CPU features
  x86/bugs: Add AMD's SPEC_CTRL MSR usage
  x86/bugs: Add AMD's variant of SSB_NO
This commit is contained in:
Linus Torvalds 2018-06-10 09:13:18 -07:00
commit a2211de0f9
5 changed files with 28 additions and 14 deletions
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2
arch/x86/include/asm/cpufeatures.h
View File

@ -282,7 +282,9 @@
#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 */
#define X86_FEATURE_AMD_SSBD (13*32+24) /* "" Speculative Store Bypass Disable */
#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
#define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */
/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */
#define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */

13
arch/x86/kernel/cpu/bugs.c
View File

@ -529,18 +529,15 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
if (mode == SPEC_STORE_BYPASS_DISABLE) {
setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
/*
* Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD uses
* a completely different MSR and bit dependent on family.
* Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
* use a completely different MSR and bit dependent on family.
*/
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_INTEL:
if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
x86_amd_ssb_disable();
else {
x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
x86_spec_ctrl_mask |= SPEC_CTRL_SSBD;
wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
break;
case X86_VENDOR_AMD:
x86_amd_ssb_disable();
break;
}
}

9
arch/x86/kernel/cpu/common.c
View File

@ -803,6 +803,12 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
set_cpu_cap(c, X86_FEATURE_STIBP);
set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
}
if (cpu_has(c, X86_FEATURE_AMD_SSBD)) {
set_cpu_cap(c, X86_FEATURE_SSBD);
set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
clear_cpu_cap(c, X86_FEATURE_VIRT_SSBD);
}
}
void get_cpu_cap(struct cpuinfo_x86 *c)
@ -992,7 +998,8 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
if (!x86_match_cpu(cpu_no_spec_store_bypass) &&
!(ia32_cap & ARCH_CAP_SSB_NO))
!(ia32_cap & ARCH_CAP_SSB_NO) &&
!cpu_has(c, X86_FEATURE_AMD_SSB_NO))
setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
if (x86_match_cpu(cpu_no_meltdown))

10
arch/x86/kvm/cpuid.c
View File

@ -379,7 +379,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
/* cpuid 0x80000008.ebx */
const u32 kvm_cpuid_8000_0008_ebx_x86_features =
F(AMD_IBPB) | F(AMD_IBRS) | F(VIRT_SSBD);
F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
F(AMD_SSB_NO);
/* cpuid 0xC0000001.edx */
const u32 kvm_cpuid_C000_0001_edx_x86_features =
@ -664,7 +665,12 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
entry->ebx |= F(VIRT_SSBD);
entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
/*
* The preference is to use SPEC CTRL MSR instead of the
* VIRT_SPEC MSR.
*/
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
!boot_cpu_has(X86_FEATURE_AMD_SSBD))
entry->ebx |= F(VIRT_SSBD);
break;
}

8
arch/x86/kvm/svm.c
View File

@ -4115,7 +4115,8 @@ 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_AMD_IBRS))
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;
msr_info->data = svm->spec_ctrl;
@ -4217,11 +4218,12 @@ 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_AMD_IBRS))
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;
/* The STIBP bit doesn't fault even if it's not advertised */
if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP))
if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD))
return 1;
svm->spec_ctrl = data;