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Message-Id: <1520855584-10079-4-git-send-email-wanpengli@tencent.com>
Date: Mon, 12 Mar 2018 04:53:04 -0700
From: Wanpeng Li <kernellwp@...il.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Jan H . Schönherr <jschoenh@...zon.de>
Subject: [PATCH v2 3/3] KVM: X86: Provides userspace with a capability to not intercept PAUSE
From: Wanpeng Li <wanpengli@...cent.com>
Allow to disable pause loop exit/pause filtering on a per VM basis.
If some VMs have dedicated host CPUs, they won't be negatively affected
due to needlessly intercepted PAUSE instructions.
Thanks to Jan H. Schönherr's initial patch.
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Jan H. Schönherr <jschoenh@...zon.de>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 3 ++-
arch/x86/kvm/vmx.c | 17 +++++++++++++----
arch/x86/kvm/x86.c | 4 +++-
arch/x86/kvm/x86.h | 9 ++++++++-
5 files changed, 27 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1a79065..d73ca26 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -813,6 +813,7 @@ struct kvm_arch {
bool mwait_in_guest;
bool hlt_in_guest;
+ bool pause_in_guest;
bool ept_identity_pagetable_done;
gpa_t ept_identity_map_addr;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0b2e7af..ddc705c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1452,7 +1452,8 @@ static void init_vmcb(struct vcpu_svm *svm)
svm->nested.vmcb = 0;
svm->vcpu.arch.hflags = 0;
- if (boot_cpu_has(X86_FEATURE_PAUSEFILTER)) {
+ if (boot_cpu_has(X86_FEATURE_PAUSEFILTER) &&
+ !kvm_pause_in_guest(svm->vcpu.kvm)) {
control->pause_filter_count = 3000;
set_intercept(svm, INTERCEPT_PAUSE);
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fa0c5e1..400f9d1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5582,7 +5582,7 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
}
if (!enable_unrestricted_guest)
exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
- if (!ple_gap)
+ if (kvm_pause_in_guest(vmx->vcpu.kvm))
exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;
if (!kvm_vcpu_apicv_active(vcpu))
exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |
@@ -5745,7 +5745,7 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmcs_write64(POSTED_INTR_DESC_ADDR, __pa((&vmx->pi_desc)));
}
- if (ple_gap) {
+ if (!kvm_pause_in_guest(vmx->vcpu.kvm)) {
vmcs_write32(PLE_GAP, ple_gap);
vmx->ple_window = ple_window;
vmx->ple_window_dirty = true;
@@ -7182,7 +7182,7 @@ static __exit void hardware_unsetup(void)
*/
static int handle_pause(struct kvm_vcpu *vcpu)
{
- if (ple_gap)
+ if (!kvm_pause_in_guest(vcpu->kvm))
grow_ple_window(vcpu);
/*
@@ -9878,6 +9878,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
return ERR_PTR(err);
}
+static int vmx_vm_init(struct kvm *kvm)
+{
+ if (!ple_gap)
+ kvm->arch.pause_in_guest = true;
+ return 0;
+}
+
static void __init vmx_check_processor_compat(void *rtn)
{
struct vmcs_config vmcs_conf;
@@ -12019,7 +12026,7 @@ static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu)
static void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu)
{
- if (ple_gap)
+ if (!kvm_pause_in_guest(vcpu->kvm))
shrink_ple_window(vcpu);
}
@@ -12379,6 +12386,8 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_accelerated_tpr = report_flexpriority,
.cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase,
+ .vm_init = vmx_vm_init,
+
.vcpu_create = vmx_create_vcpu,
.vcpu_free = vmx_free_vcpu,
.vcpu_reset = vmx_vcpu_reset,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 73255e6..8060f27 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2874,7 +2874,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = KVM_CLOCK_TSC_STABLE;
break;
case KVM_CAP_X86_DISABLE_EXITS:
- r |= KVM_X86_DISABLE_EXITS_HTL;
+ r |= KVM_X86_DISABLE_EXITS_HTL | KVM_X86_DISABLE_EXITS_PAUSE;
if(kvm_can_mwait_in_guest())
r |= KVM_X86_DISABLE_EXITS_MWAIT;
break;
@@ -4231,6 +4231,8 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
kvm->arch.mwait_in_guest = true;
if (cap->args[0] & KVM_X86_DISABLE_EXITS_HTL)
kvm->arch.hlt_in_guest = true;
+ if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE)
+ kvm->arch.pause_in_guest = true;
r = 0;
break;
default:
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index d4ddb00..658ea9a 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -264,8 +264,10 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
#define KVM_X86_DISABLE_EXITS_HTL (1 << 1)
+#define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2)
#define KVM_X86_DISABLE_VALID_EXITS (KVM_X86_DISABLE_EXITS_MWAIT | \
- KVM_X86_DISABLE_EXITS_HTL)
+ KVM_X86_DISABLE_EXITS_HTL | \
+ KVM_X86_DISABLE_EXITS_PAUSE)
static inline bool kvm_mwait_in_guest(struct kvm *kvm)
{
@@ -277,4 +279,9 @@ static inline bool kvm_hlt_in_guest(struct kvm *kvm)
return kvm->arch.hlt_in_guest;
}
+static inline bool kvm_pause_in_guest(struct kvm *kvm)
+{
+ return kvm->arch.pause_in_guest;
+}
+
#endif
--
2.7.4
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