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[PATCH v4 2/6] i386: Hyper-V Enlightened MSR bitmap feature
From: |
Vitaly Kuznetsov |
Subject: |
[PATCH v4 2/6] i386: Hyper-V Enlightened MSR bitmap feature |
Date: |
Wed, 25 May 2022 13:59:45 +0200 |
The newly introduced enlightenment allow L0 (KVM) and L1 (Hyper-V)
hypervisors to collaborate to avoid unnecessary updates to L2
MSR-Bitmap upon vmexits.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
docs/hyperv.txt | 9 +++++++++
target/i386/cpu.c | 2 ++
target/i386/cpu.h | 1 +
target/i386/kvm/hyperv-proto.h | 5 +++++
target/i386/kvm/kvm.c | 7 +++++++
5 files changed, 24 insertions(+)
diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 33588a03961f..5d85569b9941 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -239,6 +239,15 @@ This enlightenment requires a VMBus device (-device
vmbus-bridge,irq=15)
and the follow enlightenments to work:
hv-relaxed,hv_time,hv-vapic,hv-vpindex,hv-synic,hv-runtime,hv-stimer
+3.22. hv-emsr-bitmap
+=====================
+The enlightenment is nested specific, it targets Hyper-V on KVM guests. When
+enabled, it allows L0 (KVM) and L1 (Hyper-V) hypervisors to collaborate to
+avoid unnecessary updates to L2 MSR-Bitmap upon vmexits. While the protocol is
+supported for both VMX (Intel) and SVM (AMD), the VMX implementation requires
+Enlightened VMCS ('hv-evmcs') feature to also be enabled.
+
+Recommended: hv-evmcs (Intel)
4. Supplementary features
=========================
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 35c3475e6c90..5aabf0c12e8d 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6960,6 +6960,8 @@ static Property x86_cpu_properties[] = {
HYPERV_FEAT_STIMER_DIRECT, 0),
DEFINE_PROP_BIT64("hv-avic", X86CPU, hyperv_features,
HYPERV_FEAT_AVIC, 0),
+ DEFINE_PROP_BIT64("hv-emsr-bitmap", X86CPU, hyperv_features,
+ HYPERV_FEAT_MSR_BITMAP, 0),
DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU,
hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF),
DEFINE_PROP_BIT64("hv-syndbg", X86CPU, hyperv_features,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 2e918daf6bef..c7882857366d 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1106,6 +1106,7 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
#define HYPERV_FEAT_STIMER_DIRECT 14
#define HYPERV_FEAT_AVIC 15
#define HYPERV_FEAT_SYNDBG 16
+#define HYPERV_FEAT_MSR_BITMAP 17
#ifndef HYPERV_SPINLOCK_NEVER_NOTIFY
#define HYPERV_SPINLOCK_NEVER_NOTIFY 0xFFFFFFFF
diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h
index e40e59411c83..cea18dbc0e23 100644
--- a/target/i386/kvm/hyperv-proto.h
+++ b/target/i386/kvm/hyperv-proto.h
@@ -86,6 +86,11 @@
*/
#define HV_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING (1u << 1)
+/*
+ * HV_CPUID_NESTED_FEATURES.EAX bits
+ */
+#define HV_NESTED_MSR_BITMAP (1u << 19)
+
/*
* Basic virtualized MSRs
*/
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 93bfefa4a79e..82d1f0275c42 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -973,6 +973,13 @@ static struct {
.dependencies = BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_RELAXED)
},
#endif
+ [HYPERV_FEAT_MSR_BITMAP] = {
+ .desc = "enlightened MSR-Bitmap (hv-emsr-bitmap)",
+ .flags = {
+ {.func = HV_CPUID_NESTED_FEATURES, .reg = R_EAX,
+ .bits = HV_NESTED_MSR_BITMAP}
+ }
+ },
};
static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max,
--
2.35.3
- [PATCH v4 0/6] i386: Enable newly introduced KVM Hyper-V enlightenments, Vitaly Kuznetsov, 2022/05/25
- [PATCH v4 2/6] i386: Hyper-V Enlightened MSR bitmap feature,
Vitaly Kuznetsov <=
- [PATCH v4 1/6] i386: Use hv_build_cpuid_leaf() for HV_CPUID_NESTED_FEATURES, Vitaly Kuznetsov, 2022/05/25
- [PATCH v4 3/6] i386: Hyper-V XMM fast hypercall input feature, Vitaly Kuznetsov, 2022/05/25
- [PATCH v4 4/6] i386: Hyper-V Support extended GVA ranges for TLB flush hypercalls, Vitaly Kuznetsov, 2022/05/25
- [PATCH v4 5/6] i386: Hyper-V Direct TLB flush hypercall, Vitaly Kuznetsov, 2022/05/25
- [PATCH v4 6/6] i386: docs: Convert hyperv.txt to rST, Vitaly Kuznetsov, 2022/05/25
- Re: [PATCH v4 0/6] i386: Enable newly introduced KVM Hyper-V enlightenments, Paolo Bonzini, 2022/05/25