This is a note to let you know that I've just added the patch titled
KVM: x86: Advertise CPUID.(EAX=7,ECX=2):EDX[5:0] to userspace
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-advertise-cpuid.-eax-7-ecx-2-edx-to-userspace.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From eefe5e6682099445f77f2d97d4c525f9ac9d9b07 Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@xxxxxxxxxx>
Date: Mon, 23 Oct 2023 17:16:35 -0700
Subject: KVM: x86: Advertise CPUID.(EAX=7,ECX=2):EDX[5:0] to userspace
From: Jim Mattson <jmattson@xxxxxxxxxx>
commit eefe5e6682099445f77f2d97d4c525f9ac9d9b07 upstream.
The low five bits {INTEL_PSFD, IPRED_CTRL, RRSBA_CTRL, DDPD_U, BHI_CTRL}
advertise the availability of specific bits in IA32_SPEC_CTRL. Since KVM
dynamically determines the legal IA32_SPEC_CTRL bits for the underlying
hardware, the hard work has already been done. Just let userspace know
that a guest can use these IA32_SPEC_CTRL bits.
The sixth bit (MCDT_NO) states that the processor does not exhibit MXCSR
Configuration Dependent Timing (MCDT) behavior. This is an inherent
property of the physical processor that is inherited by the virtual
CPU. Pass that information on to userspace.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231024001636.890236-1-jmattson@xxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 21 ++++++++++++++++++---
arch/x86/kvm/reverse_cpuid.h | 12 ++++++++++++
2 files changed, 30 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -677,6 +677,11 @@ void kvm_set_cpu_caps(void)
F(AMX_COMPLEX)
);
+ kvm_cpu_cap_init_kvm_defined(CPUID_7_2_EDX,
+ F(INTEL_PSFD) | F(IPRED_CTRL) | F(RRSBA_CTRL) | F(DDPD_U) |
+ F(BHI_CTRL) | F(MCDT_NO)
+ );
+
kvm_cpu_cap_mask(CPUID_D_1_EAX,
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd
);
@@ -956,13 +961,13 @@ static inline int __do_cpuid_func(struct
break;
/* function 7 has additional index. */
case 7:
- entry->eax = min(entry->eax, 1u);
+ max_idx = entry->eax = min(entry->eax, 2u);
cpuid_entry_override(entry, CPUID_7_0_EBX);
cpuid_entry_override(entry, CPUID_7_ECX);
cpuid_entry_override(entry, CPUID_7_EDX);
- /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */
- if (entry->eax == 1) {
+ /* KVM only supports up to 0x7.2, capped above via min(). */
+ if (max_idx >= 1) {
entry = do_host_cpuid(array, function, 1);
if (!entry)
goto out;
@@ -972,6 +977,16 @@ static inline int __do_cpuid_func(struct
entry->ebx = 0;
entry->ecx = 0;
}
+ if (max_idx >= 2) {
+ entry = do_host_cpuid(array, function, 2);
+ if (!entry)
+ goto out;
+
+ cpuid_entry_override(entry, CPUID_7_2_EDX);
+ entry->ecx = 0;
+ entry->ebx = 0;
+ entry->eax = 0;
+ }
break;
case 0xa: { /* Architectural Performance Monitoring */
union cpuid10_eax eax;
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -16,6 +16,7 @@ enum kvm_only_cpuid_leafs {
CPUID_7_1_EDX,
CPUID_8000_0007_EDX,
CPUID_8000_0022_EAX,
+ CPUID_7_2_EDX,
NR_KVM_CPU_CAPS,
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
@@ -46,6 +47,14 @@ enum kvm_only_cpuid_leafs {
#define X86_FEATURE_AMX_COMPLEX KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
+/* Intel-defined sub-features, CPUID level 0x00000007:2 (EDX) */
+#define X86_FEATURE_INTEL_PSFD KVM_X86_FEATURE(CPUID_7_2_EDX, 0)
+#define X86_FEATURE_IPRED_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
+#define KVM_X86_FEATURE_RRSBA_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
+#define X86_FEATURE_DDPD_U KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
+#define X86_FEATURE_BHI_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
+#define X86_FEATURE_MCDT_NO KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
+
/* CPUID level 0x80000007 (EDX). */
#define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
@@ -80,6 +89,7 @@ static const struct cpuid_reg reverse_cp
[CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
[CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
[CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
+ [CPUID_7_2_EDX] = { 7, 2, CPUID_EDX},
};
/*
@@ -116,6 +126,8 @@ static __always_inline u32 __feature_tra
return KVM_X86_FEATURE_CONSTANT_TSC;
else if (x86_feature == X86_FEATURE_PERFMON_V2)
return KVM_X86_FEATURE_PERFMON_V2;
+ else if (x86_feature == X86_FEATURE_RRSBA_CTRL)
+ return KVM_X86_FEATURE_RRSBA_CTRL;
return x86_feature;
}
Patches currently in stable-queue which might be from jmattson@xxxxxxxxxx are
queue-6.6/kvm-x86-advertise-cpuid.-eax-7-ecx-2-edx-to-userspace.patch
