diff mbox series

[v3,3/5] KVM: LAPIC: Expose per-vCPU timer_advance_ns to userspace

Message ID 1557975980-9875-4-git-send-email-wanpengli@tencent.com (mailing list archive)
State New, archived
Headers show
Series KVM: LAPIC: Optimize timer latency further | expand

Commit Message

Wanpeng Li May 16, 2019, 3:06 a.m. UTC 
From: Wanpeng Li <wanpengli@tencent.com>

Expose per-vCPU timer_advance_ns to userspace, so it is able to 
query the auto-adjusted value.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
 arch/x86/kvm/debugfs.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Sean Christopherson May 17, 2019, 8:05 p.m. UTC | #1 
On Thu, May 16, 2019 at 11:06:18AM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Expose per-vCPU timer_advance_ns to userspace, so it is able to 
> query the auto-adjusted value.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Liran Alon <liran.alon@oracle.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
>  arch/x86/kvm/debugfs.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
> index c19c7ed..a6f1f93 100644
> --- a/arch/x86/kvm/debugfs.c
> +++ b/arch/x86/kvm/debugfs.c
> @@ -9,12 +9,22 @@
>   */
>  #include <linux/kvm_host.h>
>  #include <linux/debugfs.h>
> +#include "lapic.h"
>  
>  bool kvm_arch_has_vcpu_debugfs(void)
>  {
>  	return true;
>  }
>  
> +static int vcpu_get_timer_advance_ns(void *data, u64 *val)
> +{
> +	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
> +	*val = vcpu->arch.apic->lapic_timer.timer_advance_ns;

This needs to ensure to check lapic_in_kernel() to ensure apic isn't NULL.
Actually, I think we can skip creation of the parameter entirely if
lapic_in_kernel() is false.  VMX and SVM both instantiate the lapic
during kvm_arch_vcpu_create(), which is (obviously) called before
kvm_arch_create_vcpu_debugfs().

> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
> +
>  static int vcpu_get_tsc_offset(void *data, u64 *val)
>  {
>  	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
> @@ -51,6 +61,12 @@ int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
>  	if (!ret)
>  		return -ENOMEM;
>  
> +	ret = debugfs_create_file("lapic_timer_advance_ns", 0444,
> +							vcpu->debugfs_dentry,
> +							vcpu, &vcpu_timer_advance_ns_fops);
> +	if (!ret)
> +		return -ENOMEM;
> +
>  	if (kvm_has_tsc_control) {
>  		ret = debugfs_create_file("tsc-scaling-ratio", 0444,
>  							vcpu->debugfs_dentry,
> -- 
> 2.7.4
>
Wanpeng Li May 20, 2019, 8:43 a.m. UTC | #2 
On Sat, 18 May 2019 at 04:05, Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> On Thu, May 16, 2019 at 11:06:18AM +0800, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > Expose per-vCPU timer_advance_ns to userspace, so it is able to
> > query the auto-adjusted value.
> >
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Radim Krčmář <rkrcmar@redhat.com>
> > Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> > Cc: Liran Alon <liran.alon@oracle.com>
> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> > ---
> >  arch/x86/kvm/debugfs.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
> > index c19c7ed..a6f1f93 100644
> > --- a/arch/x86/kvm/debugfs.c
> > +++ b/arch/x86/kvm/debugfs.c
> > @@ -9,12 +9,22 @@
> >   */
> >  #include <linux/kvm_host.h>
> >  #include <linux/debugfs.h>
> > +#include "lapic.h"
> >
> >  bool kvm_arch_has_vcpu_debugfs(void)
> >  {
> >       return true;
> >  }
> >
> > +static int vcpu_get_timer_advance_ns(void *data, u64 *val)
> > +{
> > +     struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
> > +     *val = vcpu->arch.apic->lapic_timer.timer_advance_ns;
>
> This needs to ensure to check lapic_in_kernel() to ensure apic isn't NULL.
> Actually, I think we can skip creation of the parameter entirely if
> lapic_in_kernel() is false.  VMX and SVM both instantiate the lapic
> during kvm_arch_vcpu_create(), which is (obviously) called before
> kvm_arch_create_vcpu_debugfs().

Handle this in v4.

>
> > +     return 0;
> > +}
> > +
> > +DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
> > +
> >  static int vcpu_get_tsc_offset(void *data, u64 *val)
> >  {
> >       struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
> > @@ -51,6 +61,12 @@ int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
> >       if (!ret)
> >               return -ENOMEM;
> >
> > +     ret = debugfs_create_file("lapic_timer_advance_ns", 0444,
> > +                                                     vcpu->debugfs_dentry,
> > +                                                     vcpu, &vcpu_timer_advance_ns_fops);
> > +     if (!ret)
> > +             return -ENOMEM;
> > +
> >       if (kvm_has_tsc_control) {
> >               ret = debugfs_create_file("tsc-scaling-ratio", 0444,
> >                                                       vcpu->debugfs_dentry,
> > --
> > 2.7.4
> >
diff mbox series

Patch

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index c19c7ed..a6f1f93 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -9,12 +9,22 @@ 
  */
 #include <linux/kvm_host.h>
 #include <linux/debugfs.h>
+#include "lapic.h"
 
 bool kvm_arch_has_vcpu_debugfs(void)
 {
 	return true;
 }
 
+static int vcpu_get_timer_advance_ns(void *data, u64 *val)
+{
+	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
+	*val = vcpu->arch.apic->lapic_timer.timer_advance_ns;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
+
 static int vcpu_get_tsc_offset(void *data, u64 *val)
 {
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
@@ -51,6 +61,12 @@  int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
 	if (!ret)
 		return -ENOMEM;
 
+	ret = debugfs_create_file("lapic_timer_advance_ns", 0444,
+							vcpu->debugfs_dentry,
+							vcpu, &vcpu_timer_advance_ns_fops);
+	if (!ret)
+		return -ENOMEM;
+
 	if (kvm_has_tsc_control) {
 		ret = debugfs_create_file("tsc-scaling-ratio", 0444,
 							vcpu->debugfs_dentry,