This is a note to let you know that I've just added the patch titled
KVM: x86: Update KVM-only leaf handling to allow for 100% KVM-only leafs
to the 5.15-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-update-kvm-only-leaf-handling-to-allow-for-100-kvm-only-leafs.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 047c7229906152fb85c23dc18fd25a00cd7cb4de Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Fri, 25 Nov 2022 20:58:39 +0800
Subject: KVM: x86: Update KVM-only leaf handling to allow for 100% KVM-only leafs
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 047c7229906152fb85c23dc18fd25a00cd7cb4de upstream.
Rename kvm_cpu_cap_init_scattered() to kvm_cpu_cap_init_kvm_defined() in
anticipation of adding KVM-only CPUID leafs that aren't recognized by the
kernel and thus not scattered, i.e. for leafs that are 100% KVM-defined.
Adjust/add comments to kvm_only_cpuid_leafs and KVM_X86_FEATURE to
document how to create new kvm_only_cpuid_leafs entries for scattered
features as well as features that are entirely unknown to the kernel.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20221125125845.1182922-3-jiaxi.chen@xxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 8 ++++----
arch/x86/kvm/reverse_cpuid.h | 18 +++++++++++++++---
2 files changed, 19 insertions(+), 7 deletions(-)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -355,9 +355,9 @@ static __always_inline void __kvm_cpu_ca
}
static __always_inline
-void kvm_cpu_cap_init_scattered(enum kvm_only_cpuid_leafs leaf, u32 mask)
+void kvm_cpu_cap_init_kvm_defined(enum kvm_only_cpuid_leafs leaf, u32 mask)
{
- /* Use kvm_cpu_cap_mask for non-scattered leafs. */
+ /* Use kvm_cpu_cap_mask for leafs that aren't KVM-only. */
BUILD_BUG_ON(leaf < NCAPINTS);
kvm_cpu_caps[leaf] = mask;
@@ -367,7 +367,7 @@ void kvm_cpu_cap_init_scattered(enum kvm
static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
{
- /* Use kvm_cpu_cap_init_scattered for scattered leafs. */
+ /* Use kvm_cpu_cap_init_kvm_defined for KVM-only leafs. */
BUILD_BUG_ON(leaf >= NCAPINTS);
kvm_cpu_caps[leaf] &= mask;
@@ -473,7 +473,7 @@ void kvm_set_cpu_caps(void)
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES)
);
- kvm_cpu_cap_init_scattered(CPUID_12_EAX,
+ kvm_cpu_cap_init_kvm_defined(CPUID_12_EAX,
SF(SGX1) | SF(SGX2)
);
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -7,9 +7,9 @@
#include <asm/cpufeatures.h>
/*
- * Hardware-defined CPUID leafs that are scattered in the kernel, but need to
- * be directly used by KVM. Note, these word values conflict with the kernel's
- * "bug" caps, but KVM doesn't use those.
+ * Hardware-defined CPUID leafs that are either scattered by the kernel or are
+ * unknown to the kernel, but need to be directly used by KVM. Note, these
+ * word values conflict with the kernel's "bug" caps, but KVM doesn't use those.
*/
enum kvm_only_cpuid_leafs {
CPUID_12_EAX = NCAPINTS,
@@ -18,6 +18,18 @@ enum kvm_only_cpuid_leafs {
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
};
+/*
+ * Define a KVM-only feature flag.
+ *
+ * For features that are scattered by cpufeatures.h, __feature_translate() also
+ * needs to be updated to translate the kernel-defined feature into the
+ * KVM-defined feature.
+ *
+ * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
+ * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
+ * that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is
+ * needed in this case.
+ */
#define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-5.15/x86-cpu-support-amd-automatic-ibrs.patch
queue-5.15/kvm-x86-advertise-cpuid.-eax-7-ecx-2-edx-to-userspace.patch
queue-5.15/kvm-x86-update-kvm-only-leaf-handling-to-allow-for-100-kvm-only-leafs.patch
