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.
Signed-off-by: Jan H. Schönherr <jschoenh@xxxxxxxxx>
---
Note: AMD code paths are only compile tested
---
Documentation/virtual/kvm/api.txt | 8 ++++++++
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 | 5 +++++
arch/x86/kvm/x86.h | 5 +++++
include/uapi/linux/kvm.h | 1 +
7 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c06bb41..42a54d1 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4184,6 +4184,14 @@ This capability indicates that a guest using HLT to stop a virtual CPU will not
cause a VM exit. As such, time spent while a virtual CPU is halted in this way
will then be accounted for as guest running time on the host.
+7.15 KVM_CAP_X86_GUEST_PAUSE
+
+Architectures: x86
+Parameters: none
+Returns: 0 on success
+
+This capability indicates that a guest using PAUSE will not cause a VM exit.
+
8. Other capabilities.
----------------------
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3197c2d..0d4ea32 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -782,6 +782,7 @@ struct kvm_arch {
gpa_t wall_clock;
bool hlt_in_guest;
+ bool pause_in_guest;
bool mwait_in_guest;
bool ept_identity_pagetable_done;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c135b98..a5eb60a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1314,7 +1314,8 @@ 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 1b67433..5f8c33b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5352,7 +5352,7 @@ 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 |
@@ -5519,7 +5519,7 @@ 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;
@@ -6975,7 +6975,7 @@ 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);
/*
@@ -9730,6 +9730,13 @@ 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;
@@ -11793,7 +11800,7 @@ 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);
}
@@ -12152,6 +12159,8 @@ 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 f17c520..e13df00 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2756,6 +2756,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_SPLIT_IRQCHIP:
case KVM_CAP_IMMEDIATE_EXIT:
case KVM_CAP_X86_GUEST_HLT:
+ case KVM_CAP_X86_GUEST_PAUSE:
r = 1;
break;
case KVM_CAP_ADJUST_CLOCK:
@@ -4073,6 +4074,10 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
kvm->arch.hlt_in_guest = true;
r = 0;
break;
+ case KVM_CAP_X86_GUEST_PAUSE:
+ kvm->arch.pause_in_guest = true;
+ r = 0;
+ break;
default:
r = -EINVAL;
break;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index b2066aa..56297c4 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -271,4 +271,9 @@ 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
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index ff8f266..bc2b654 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -933,6 +933,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_HYPERV_VP_INDEX 149
#define KVM_CAP_S390_AIS_MIGRATION 150
#define KVM_CAP_X86_GUEST_HLT 151
+#define KVM_CAP_X86_GUEST_PAUSE 152
#ifdef KVM_CAP_IRQ_ROUTING
--
2.3.1.dirty
