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KVM: X86: Provide a capability to disable PAUSE intercepts 

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@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Wanpeng Li 2018-03-12 04:53:04 -07:00 committed by Paolo Bonzini
parent caa057a2ca
commit b31c114b82
5 changed files with 27 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/kvm_host.h
View File

@ -813,6 +813,7 @@ struct kvm_arch {
bool mwait_in_guest; bool mwait_in_guest;
bool hlt_in_guest; bool hlt_in_guest;
bool pause_in_guest;
bool ept_identity_pagetable_done; bool ept_identity_pagetable_done;
gpa_t ept_identity_map_addr; gpa_t ept_identity_map_addr;

3
arch/x86/kvm/svm.c
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@ -1460,7 +1460,8 @@ static void init_vmcb(struct vcpu_svm *svm)
svm->nested.vmcb = 0; svm->nested.vmcb = 0;
svm->vcpu.arch.hflags = 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; control->pause_filter_count = 3000;
set_intercept(svm, INTERCEPT_PAUSE); set_intercept(svm, INTERCEPT_PAUSE);
} }

17
arch/x86/kvm/vmx.c
View File

@ -5595,7 +5595,7 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
} }
if (!enable_unrestricted_guest) if (!enable_unrestricted_guest)
exec_control &= ~SECONDARY_EXEC_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; exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;
if (!kvm_vcpu_apicv_active(vcpu)) if (!kvm_vcpu_apicv_active(vcpu))
exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT | exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |
@ -5758,7 +5758,7 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmcs_write64(POSTED_INTR_DESC_ADDR, __pa((&vmx->pi_desc))); 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); vmcs_write32(PLE_GAP, ple_gap);
vmx->ple_window = ple_window; vmx->ple_window = ple_window;
vmx->ple_window_dirty = true; vmx->ple_window_dirty = true;
@ -7207,7 +7207,7 @@ static __exit void hardware_unsetup(void)
*/ */
static int handle_pause(struct kvm_vcpu *vcpu) static int handle_pause(struct kvm_vcpu *vcpu)
{ {
if (ple_gap) if (!kvm_pause_in_guest(vcpu->kvm))
grow_ple_window(vcpu); grow_ple_window(vcpu);
/* /*
@ -9903,6 +9903,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
return ERR_PTR(err); 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) static void __init vmx_check_processor_compat(void *rtn)
{ {
struct vmcs_config vmcs_conf; struct vmcs_config vmcs_conf;
@ -12052,7 +12059,7 @@ static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu)
static void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu) 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); shrink_ple_window(vcpu);
} }
@ -12412,6 +12419,8 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_accelerated_tpr = report_flexpriority, .cpu_has_accelerated_tpr = report_flexpriority,
.cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase, .cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase,
.vm_init = vmx_vm_init,
.vcpu_create = vmx_create_vcpu, .vcpu_create = vmx_create_vcpu,
.vcpu_free = vmx_free_vcpu, .vcpu_free = vmx_free_vcpu,
.vcpu_reset = vmx_vcpu_reset, .vcpu_reset = vmx_vcpu_reset,

4
arch/x86/kvm/x86.c
View File

@ -2878,7 +2878,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = KVM_CLOCK_TSC_STABLE; r = KVM_CLOCK_TSC_STABLE;
break; break;
case KVM_CAP_X86_DISABLE_EXITS: 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()) if(kvm_can_mwait_in_guest())
r |= KVM_X86_DISABLE_EXITS_MWAIT; r |= KVM_X86_DISABLE_EXITS_MWAIT;
break; break;
@ -4235,6 +4235,8 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
kvm->arch.mwait_in_guest = true; kvm->arch.mwait_in_guest = true;
if (cap->args[0] & KVM_X86_DISABLE_EXITS_HTL) if (cap->args[0] & KVM_X86_DISABLE_EXITS_HTL)
kvm->arch.hlt_in_guest = true; kvm->arch.hlt_in_guest = true;
if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE)
kvm->arch.pause_in_guest = true;
r = 0; r = 0;
break; break;
default: default:

9
arch/x86/kvm/x86.h
View File

@ -266,8 +266,10 @@ 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_MWAIT (1 << 0)
#define KVM_X86_DISABLE_EXITS_HTL (1 << 1) #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 | \ #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) static inline bool kvm_mwait_in_guest(struct kvm *kvm)
{ {
@ -279,4 +281,9 @@ static inline bool kvm_hlt_in_guest(struct kvm *kvm)
return kvm->arch.hlt_in_guest; return kvm->arch.hlt_in_guest;
} }
static inline bool kvm_pause_in_guest(struct kvm *kvm)
{
return kvm->arch.pause_in_guest;
}
#endif #endif