Re: trace_printk() support in trace-cmd

[Avi Kivity <avi@redhat.com>]

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On 12/13/2010 06:28 PM, Steven Rostedt wrote:
> On Mon, 2010-12-13 at 17:43 +0200, Avi Kivity wrote:
>
> >  >    What's your work flow? Do you
> >  >  load kvm modules after you start the trace, or are they always loaded?
> >
> >  Loaded on boot.
>
> Via initramfs?

No, regular printks.

> >
> >  >  Are the trace_printk's in the core kernel too, and not being printed?
> >
> >  I don't have any trace_printk()s in the core kernel, only in modules.
> >  Perhaps module initialization does not communicate trace_printk formats?
>
> They should.
>
> Could you send me a patch that has the trace_printk()s you are using.
>

Attached (with __trace_printk()s, which is what I used).


-- 
error compiling committee.c: too many arguments to function


[-- Attachment #2: trace-printk.patch --]
[-- Type: text/x-patch, Size: 2400 bytes --]

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index d75ba1e..df86917 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1449,6 +1449,10 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
 	if (role.direct)
 		role.cr4_pae = 0;
 	role.access = access;
+	__trace_printk(_THIS_IP_,
+		       "base_role %x access %x role.access %x role %x\n",
+		       vcpu->arch.mmu.base_role, access, role.access,
+		       role.word);
 	if (!vcpu->arch.mmu.direct_map
 	    && vcpu->arch.mmu.root_level <= PT32_ROOT_LEVEL) {
 		quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
@@ -1576,6 +1580,11 @@ static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		if (child->role.access == direct_access)
 			return;
 
+		__trace_printk(_THIS_IP_,
+			       "child->role %x child->role.access %x direct_access %x\n",
+			       child->role.word, child->role.access,
+			       direct_access);
+
 		mmu_page_remove_parent_pte(child, sptep);
 		__set_spte(sptep, shadow_trap_nonpresent_pte);
 		kvm_flush_remote_tlbs(vcpu->kvm);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 4f61fbb..1049729 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -450,6 +450,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 	if (!is_present_gpte(gw->ptes[gw->level - 1]))
 		return NULL;
 
+	__trace_printk(_THIS_IP_, "pt_access %x pte_access %x dirty %d\n",
+		       gw->pt_access, gw->pte_access, dirty);
 	direct_access = gw->pt_access & gw->pte_access;
 	if (!dirty)
 		direct_access &= ~ACC_WRITE_MASK;
@@ -592,6 +594,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 	if (is_error_pfn(pfn))
 		return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
 
+	__trace_printk(_THIS_IP_, "page_fault: map_writeable %x\n",
+		       map_writable);
+
 	spin_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu, mmu_seq))
 		goto out_unlock;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 83f5bf6..05481a3 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1015,6 +1015,8 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
 	if (unlikely(npages != 1) && !atomic) {
 		might_sleep();
 
+		__trace_printk(_THIS_IP_, "%s: addr %lx not writeable\n",
+			       __func__, addr);
 		if (writable)
 			*writable = write_fault;