From: lantianyu1986@gmail.com
To: pbonzini@redhat.com, rkrcmar@redhat.com, corbet@lwn.net,
kys@microsoft.com, haiyangz@microsoft.com,
sthemmin@microsoft.com, sashal@kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
michael.h.kelley@microsoft.com
Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
vkuznets@redhat.com
Subject: [PATCH V3 2/3] KVM/Hyper-V: Add new KVM cap KVM_CAP_HYPERV_DIRECT_TLBFLUSH
Date: Mon, 19 Aug 2019 21:17:36 +0800 [thread overview]
Message-ID: <20190819131737.26942-3-Tianyu.Lan@microsoft.com> (raw)
In-Reply-To: <20190819131737.26942-1-Tianyu.Lan@microsoft.com>
From: Tianyu Lan <Tianyu.Lan@microsoft.com>
This patch adds new KVM cap KVM_CAP_HYPERV_DIRECT_TLBFLUSH and let
user space to enable direct tlb flush function when only Hyper-V
hypervsior capability is exposed to VM. This patch also adds
enable_direct_tlbflush callback in the struct kvm_x86_ops and
platforms may use it to implement direct tlb flush support.
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
Change since v1:
Update description of KVM_CAP_HYPERV_DIRECT_TLBFLUSH
in the KVM API doc.
---
Documentation/virtual/kvm/api.txt | 13 +++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/x86.c | 8 ++++++++
include/uapi/linux/kvm.h | 1 +
4 files changed, 24 insertions(+)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 2cd6250b2896..0c6e1b25d0c8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -5289,3 +5289,16 @@ Architectures: x86
This capability indicates that KVM supports paravirtualized Hyper-V IPI send
hypercalls:
HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx.
+8.21 KVM_CAP_HYPERV_DIRECT_TLBFLUSH
+
+Architecture: x86
+
+This capability indicates that KVM running on top of Hyper-V hypervisor
+enables Direct TLB flush for its guests meaning that TLB flush
+hypercalls are handled by Level 0 hypervisor (Hyper-V) bypassing KVM.
+Due to the different ABI for hypercall parameters between Hyper-V and
+KVM, enabling this capability effectively disables all hypercall
+handling by KVM (as some KVM hypercall may be mistakenly treated as TLB
+flush hypercalls by Hyper-V) so userspace should disable KVM identification
+in CPUID and only exposes Hyper-V identification. In this case, guest
+thinks it's running on Hyper-V and only use Hyper-V hypercalls.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0cc5b611a113..667d154e89d4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1205,6 +1205,8 @@ struct kvm_x86_ops {
uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);
bool (*need_emulation_on_page_fault)(struct kvm_vcpu *vcpu);
+
+ int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu);
};
struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9d7b9e6a0939..a9d8ee7f7bf0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3183,6 +3183,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = kvm_x86_ops->get_nested_state ?
kvm_x86_ops->get_nested_state(NULL, NULL, 0) : 0;
break;
+ case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
+ r = kvm_x86_ops->enable_direct_tlbflush ? 1 : 0;
+ break;
default:
break;
}
@@ -3953,6 +3956,11 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
r = -EFAULT;
}
return r;
+ case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
+ if (!kvm_x86_ops->enable_direct_tlbflush)
+ return -ENOTTY;
+
+ return kvm_x86_ops->enable_direct_tlbflush(vcpu);
default:
return -EINVAL;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a7c19540ce21..cb959bc925b1 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -996,6 +996,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_ARM_PTRAUTH_ADDRESS 171
#define KVM_CAP_ARM_PTRAUTH_GENERIC 172
#define KVM_CAP_PMU_EVENT_FILTER 173
+#define KVM_CAP_HYPERV_DIRECT_TLBFLUSH 174
#ifdef KVM_CAP_IRQ_ROUTING
--
2.14.5
next prev parent reply other threads:[~2019-08-19 13:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 13:17 [PATCH V3 0/3] KVM/Hyper-V: Add Hyper-V direct tlb flush support lantianyu1986
2019-08-19 13:17 ` [PATCH V3 1/3] x86/Hyper-V: Fix definition of struct hv_vp_assist_page lantianyu1986
2019-08-19 13:30 ` Thomas Gleixner
2019-08-19 13:17 ` lantianyu1986 [this message]
2019-08-19 13:27 ` [PATCH V3 2/3] KVM/Hyper-V: Add new KVM cap KVM_CAP_HYPERV_DIRECT_TLBFLUSH Thomas Gleixner
2019-08-20 12:38 ` Tianyu Lan
2019-08-19 13:17 ` [PATCH V3 3/3] KVM/Hyper-V/VMX: Add direct tlb flush support lantianyu1986
2019-08-19 13:29 ` Thomas Gleixner
2019-08-27 6:41 ` [PATCH V3 0/3] KVM/Hyper-V: Add Hyper-V " Vitaly Kuznetsov
2019-08-27 12:17 ` Tianyu Lan
2019-08-27 12:33 ` Tianyu Lan
2019-08-27 12:38 ` Vitaly Kuznetsov
2019-08-27 13:07 ` Tianyu Lan
2019-08-27 13:29 ` Vitaly Kuznetsov
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