[PATCH v4 0/4] KVM: X86: Some tracepoint enhancements

[PATCH v4 0/4] KVM: X86: Some tracepoint enhancements

[Peter Xu]

v4:
- pick r-b
- swap the last two patches [Sean]

v3:
- use unsigned int for vcpu id [Sean]
- a new patch to fix ple_window type [Sean]

v2:
- fix commit messages, change format of ple window tracepoint [Sean]
- rebase [Wanpeng]

Each small patch explains itself.  I noticed them when I'm tracing
some IRQ paths and I found them helpful at least to me.

Please have a look.  Thanks,

Peter Xu (4):
  KVM: X86: Trace vcpu_id for vmexit
  KVM: X86: Remove tailing newline for tracepoints
  KVM: VMX: Change ple_window type to unsigned int
  KVM: X86: Tune PLE Window tracepoint

 arch/x86/kvm/svm.c     | 16 ++++++++--------
 arch/x86/kvm/trace.h   | 34 ++++++++++++++--------------------
 arch/x86/kvm/vmx/vmx.c | 18 ++++++++++--------
 arch/x86/kvm/vmx/vmx.h |  2 +-
 arch/x86/kvm/x86.c     |  2 +-
 5 files changed, 34 insertions(+), 38 deletions(-)

-- 
2.21.0

[PATCH v4 1/4] KVM: X86: Trace vcpu_id for vmexit

[Peter Xu]

Tracing the ID helps to pair vmenters and vmexits for guests with
multiple vCPUs.

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/x86/kvm/trace.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index b5c831e79094..20d6cac9f157 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -232,17 +232,20 @@ TRACE_EVENT(kvm_exit,
 		__field(	u32,	        isa             )
 		__field(	u64,	        info1           )
 		__field(	u64,	        info2           )
+		__field(	unsigned int,	vcpu_id         )
 	),
 
 	TP_fast_assign(
 		__entry->exit_reason	= exit_reason;
 		__entry->guest_rip	= kvm_rip_read(vcpu);
 		__entry->isa            = isa;
+		__entry->vcpu_id        = vcpu->vcpu_id;
 		kvm_x86_ops->get_exit_info(vcpu, &__entry->info1,
 					   &__entry->info2);
 	),
 
-	TP_printk("reason %s rip 0x%lx info %llx %llx",
+	TP_printk("vcpu %u reason %s rip 0x%lx info %llx %llx",
+		  __entry->vcpu_id,
 		 (__entry->isa == KVM_ISA_VMX) ?
 		 __print_symbolic(__entry->exit_reason, VMX_EXIT_REASONS) :
 		 __print_symbolic(__entry->exit_reason, SVM_EXIT_REASONS),
-- 
2.21.0

[PATCH v4 2/4] KVM: X86: Remove tailing newline for tracepoints

[Peter Xu]

It's done by TP_printk() already.

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/x86/kvm/trace.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 20d6cac9f157..8a7570f8c943 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1323,7 +1323,7 @@ TRACE_EVENT(kvm_avic_incomplete_ipi,
 		__entry->index = index;
 	),
 
-	TP_printk("vcpu=%u, icrh:icrl=%#010x:%08x, id=%u, index=%u\n",
+	TP_printk("vcpu=%u, icrh:icrl=%#010x:%08x, id=%u, index=%u",
 		  __entry->vcpu, __entry->icrh, __entry->icrl,
 		  __entry->id, __entry->index)
 );
@@ -1348,7 +1348,7 @@ TRACE_EVENT(kvm_avic_unaccelerated_access,
 		__entry->vec = vec;
 	),
 
-	TP_printk("vcpu=%u, offset=%#x(%s), %s, %s, vec=%#x\n",
+	TP_printk("vcpu=%u, offset=%#x(%s), %s, %s, vec=%#x",
 		  __entry->vcpu,
 		  __entry->offset,
 		  __print_symbolic(__entry->offset, kvm_trace_symbol_apic),
-- 
2.21.0

[PATCH v4 3/4] KVM: VMX: Change ple_window type to unsigned int

[Peter Xu]

The VMX ple_window is 32 bits wide, so logically it can overflow with
an int.  The module parameter is declared as unsigned int which is
good, however the dynamic variable is not.  Switching all the
ple_window references to use unsigned int.

The tracepoint changes will also affect SVM, but SVM is using an even
smaller width (16 bits) so it's always fine.

Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/x86/kvm/trace.h   | 9 +++++----
 arch/x86/kvm/vmx/vmx.c | 4 ++--
 arch/x86/kvm/vmx/vmx.h | 2 +-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 8a7570f8c943..afe8d269c16c 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -891,14 +891,15 @@ TRACE_EVENT(kvm_pml_full,
 );
 
 TRACE_EVENT(kvm_ple_window,
-	TP_PROTO(bool grow, unsigned int vcpu_id, int new, int old),
+	TP_PROTO(bool grow, unsigned int vcpu_id, unsigned int new,
+		 unsigned int old),
 	TP_ARGS(grow, vcpu_id, new, old),
 
 	TP_STRUCT__entry(
 		__field(                bool,      grow         )
 		__field(        unsigned int,   vcpu_id         )
-		__field(                 int,       new         )
-		__field(                 int,       old         )
+		__field(        unsigned int,       new         )
+		__field(        unsigned int,       old         )
 	),
 
 	TP_fast_assign(
@@ -908,7 +909,7 @@ TRACE_EVENT(kvm_ple_window,
 		__entry->old            = old;
 	),
 
-	TP_printk("vcpu %u: ple_window %d (%s %d)",
+	TP_printk("vcpu %u: ple_window %u (%s %u)",
 	          __entry->vcpu_id,
 	          __entry->new,
 	          __entry->grow ? "grow" : "shrink",
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 42ed3faa6af8..b172b675d420 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5227,7 +5227,7 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
 static void grow_ple_window(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	int old = vmx->ple_window;
+	unsigned int old = vmx->ple_window;
 
 	vmx->ple_window = __grow_ple_window(old, ple_window,
 					    ple_window_grow,
@@ -5242,7 +5242,7 @@ static void grow_ple_window(struct kvm_vcpu *vcpu)
 static void shrink_ple_window(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	int old = vmx->ple_window;
+	unsigned int old = vmx->ple_window;
 
 	vmx->ple_window = __shrink_ple_window(old, ple_window,
 					      ple_window_shrink,
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 82d0bc3a4d52..64d5a4890aa9 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -253,7 +253,7 @@ struct vcpu_vmx {
 	struct nested_vmx nested;
 
 	/* Dynamic PLE window. */
-	int ple_window;
+	unsigned int ple_window;
 	bool ple_window_dirty;
 
 	bool req_immediate_exit;
-- 
2.21.0

Re: [PATCH v4 3/4] KVM: VMX: Change ple_window type to unsigned int

[Sean Christopherson]

On Fri, Sep 06, 2019 at 10:17:21AM +0800, Peter Xu wrote:
> The VMX ple_window is 32 bits wide, so logically it can overflow with
> an int.  The module parameter is declared as unsigned int which is
> good, however the dynamic variable is not.  Switching all the
> ple_window references to use unsigned int.
> 
> The tracepoint changes will also affect SVM, but SVM is using an even
> smaller width (16 bits) so it's always fine.
> 
> Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

[PATCH v4 4/4] KVM: X86: Tune PLE Window tracepoint

[Peter Xu]

The PLE window tracepoint triggers even if the window is not changed,
and the wording can be a bit confusing too.  One example line:

  kvm_ple_window: vcpu 0: ple_window 4096 (shrink 4096)

It easily let people think of "the window now is 4096 which is
shrinked", but the truth is the value actually didn't change (4096).

Let's only dump this message if the value really changed, and we make
the message even simpler like:

  kvm_ple_window: vcpu 4 old 4096 new 8192 (growed)

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/x86/kvm/svm.c     | 16 ++++++++--------
 arch/x86/kvm/trace.h   | 22 ++++++----------------
 arch/x86/kvm/vmx/vmx.c | 14 ++++++++------
 arch/x86/kvm/x86.c     |  2 +-
 4 files changed, 23 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d685491fce4d..d5cb6b5a9254 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1269,11 +1269,11 @@ static void grow_ple_window(struct kvm_vcpu *vcpu)
 							pause_filter_count_grow,
 							pause_filter_count_max);
 
-	if (control->pause_filter_count != old)
+	if (control->pause_filter_count != old) {
 		mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
-
-	trace_kvm_ple_window_grow(vcpu->vcpu_id,
-				  control->pause_filter_count, old);
+		trace_kvm_ple_window_update(vcpu->vcpu_id,
+					    control->pause_filter_count, old);
+	}
 }
 
 static void shrink_ple_window(struct kvm_vcpu *vcpu)
@@ -1287,11 +1287,11 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu)
 						    pause_filter_count,
 						    pause_filter_count_shrink,
 						    pause_filter_count);
-	if (control->pause_filter_count != old)
+	if (control->pause_filter_count != old) {
 		mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
-
-	trace_kvm_ple_window_shrink(vcpu->vcpu_id,
-				    control->pause_filter_count, old);
+		trace_kvm_ple_window_update(vcpu->vcpu_id,
+					    control->pause_filter_count, old);
+	}
 }
 
 static __init int svm_hardware_setup(void)
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index afe8d269c16c..ae924566c401 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -890,37 +890,27 @@ TRACE_EVENT(kvm_pml_full,
 	TP_printk("vcpu %d: PML full", __entry->vcpu_id)
 );
 
-TRACE_EVENT(kvm_ple_window,
-	TP_PROTO(bool grow, unsigned int vcpu_id, unsigned int new,
-		 unsigned int old),
-	TP_ARGS(grow, vcpu_id, new, old),
+TRACE_EVENT(kvm_ple_window_update,
+	TP_PROTO(unsigned int vcpu_id, unsigned int new, unsigned int old),
+	TP_ARGS(vcpu_id, new, old),
 
 	TP_STRUCT__entry(
-		__field(                bool,      grow         )
 		__field(        unsigned int,   vcpu_id         )
 		__field(        unsigned int,       new         )
 		__field(        unsigned int,       old         )
 	),
 
 	TP_fast_assign(
-		__entry->grow           = grow;
 		__entry->vcpu_id        = vcpu_id;
 		__entry->new            = new;
 		__entry->old            = old;
 	),
 
-	TP_printk("vcpu %u: ple_window %u (%s %u)",
-	          __entry->vcpu_id,
-	          __entry->new,
-	          __entry->grow ? "grow" : "shrink",
-	          __entry->old)
+	TP_printk("vcpu %u old %u new %u (%s)",
+	          __entry->vcpu_id, __entry->old, __entry->new,
+		  __entry->old < __entry->new ? "growed" : "shrinked")
 );
 
-#define trace_kvm_ple_window_grow(vcpu_id, new, old) \
-	trace_kvm_ple_window(true, vcpu_id, new, old)
-#define trace_kvm_ple_window_shrink(vcpu_id, new, old) \
-	trace_kvm_ple_window(false, vcpu_id, new, old)
-
 TRACE_EVENT(kvm_pvclock_update,
 	TP_PROTO(unsigned int vcpu_id, struct pvclock_vcpu_time_info *pvclock),
 	TP_ARGS(vcpu_id, pvclock),
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b172b675d420..1dbb63ffdd6d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5233,10 +5233,11 @@ static void grow_ple_window(struct kvm_vcpu *vcpu)
 					    ple_window_grow,
 					    ple_window_max);
 
-	if (vmx->ple_window != old)
+	if (vmx->ple_window != old) {
 		vmx->ple_window_dirty = true;
-
-	trace_kvm_ple_window_grow(vcpu->vcpu_id, vmx->ple_window, old);
+		trace_kvm_ple_window_update(vcpu->vcpu_id,
+					    vmx->ple_window, old);
+	}
 }
 
 static void shrink_ple_window(struct kvm_vcpu *vcpu)
@@ -5248,10 +5249,11 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu)
 					      ple_window_shrink,
 					      ple_window);
 
-	if (vmx->ple_window != old)
+	if (vmx->ple_window != old) {
 		vmx->ple_window_dirty = true;
-
-	trace_kvm_ple_window_shrink(vcpu->vcpu_id, vmx->ple_window, old);
+		trace_kvm_ple_window_update(vcpu->vcpu_id,
+					    vmx->ple_window, old);
+	}
 }
 
 /*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 93b0bd45ac73..69ad184edc90 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10082,7 +10082,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_invlpga);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_skinit);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_intercepts);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_write_tsc_offset);
-EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_ple_window);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_ple_window_update);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_pml_full);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_pi_irte_update);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_unaccelerated_access);
-- 
2.21.0

Re: [PATCH v4 4/4] KVM: X86: Tune PLE Window tracepoint

[Sean Christopherson]

On Fri, Sep 06, 2019 at 10:17:22AM +0800, Peter Xu wrote:
> The PLE window tracepoint triggers even if the window is not changed,
> and the wording can be a bit confusing too.  One example line:
> 
>   kvm_ple_window: vcpu 0: ple_window 4096 (shrink 4096)
> 
> It easily let people think of "the window now is 4096 which is
> shrinked", but the truth is the value actually didn't change (4096).
> 
> Let's only dump this message if the value really changed, and we make
> the message even simpler like:
> 
>   kvm_ple_window: vcpu 4 old 4096 new 8192 (growed)
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

Re: [PATCH v4 0/4] KVM: X86: Some tracepoint enhancements

[Paolo Bonzini]

On 06/09/19 04:17, Peter Xu wrote:
> v4:
> - pick r-b
> - swap the last two patches [Sean]
> 
> v3:
> - use unsigned int for vcpu id [Sean]
> - a new patch to fix ple_window type [Sean]
> 
> v2:
> - fix commit messages, change format of ple window tracepoint [Sean]
> - rebase [Wanpeng]
> 
> Each small patch explains itself.  I noticed them when I'm tracing
> some IRQ paths and I found them helpful at least to me.
> 
> Please have a look.  Thanks,
> 
> Peter Xu (4):
>   KVM: X86: Trace vcpu_id for vmexit
>   KVM: X86: Remove tailing newline for tracepoints
>   KVM: VMX: Change ple_window type to unsigned int
>   KVM: X86: Tune PLE Window tracepoint
> 
>  arch/x86/kvm/svm.c     | 16 ++++++++--------
>  arch/x86/kvm/trace.h   | 34 ++++++++++++++--------------------
>  arch/x86/kvm/vmx/vmx.c | 18 ++++++++++--------
>  arch/x86/kvm/vmx/vmx.h |  2 +-
>  arch/x86/kvm/x86.c     |  2 +-
>  5 files changed, 34 insertions(+), 38 deletions(-)
> 

Queued, thanks.

Paolo