[PATCH 4/7] KVM: x86: Add intr/vectoring info and error code to kvm_exit tracepoint

Sean Christopherson
2020-07-18T06:39:36Z

Extend the kvm_exit tracepoint to align it with kvm_nested_vmexit in
terms of what information is captured. On SVM, this means adding
interrupt info and error code, and on VMX it means adding ITD vectoring
and error code. This sets the stage for macrofying the kvm_exit
tracepoint definition so that it can be reused for kvm_nested_vmexit
without loss of information (and the nested version is more helpful).

Opportunistically stuff a zero for VM_EXIT_INTR_INFO if the VM-Enter
failed, as the field is guaranteed to be invalid. Note, it'd be
possible to further filter the interrupt/exception fields based on the
VM-Exit reason, but the helper is intended only for tracepoints, i.e.
an extra VMREAD or two is a non-issue, the failed VM-Enter case is just
low hanging fruit.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 7 ++++++-
arch/x86/kvm/svm/svm.c | 9 ++++++++-
arch/x86/kvm/trace.h | 12 +++++++++---
arch/x86/kvm/vmx/vmx.c | 18 ++++++++++++++++--
4 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1bab87a444d78..d8a24252e20e1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1143,7 +1143,12 @@ struct kvm_x86_ops {
/* Returns actual tsc_offset set in active VMCS */
u64 (*write_l1_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);

- void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
+ /*
+ * Retrieve somewhat arbitrary exit information. Intended to be used
+ * only from within tracepoints to avoid VMREADs when tracing is off.
+ */
+ void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2,
+ u32 *exit_int_info, u32 *exit_int_info_err_code);

int (*check_intercept)(struct kvm_vcpu *vcpu,
struct x86_instruction_info *info,
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1fea39ff33077..8ab3413094500 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2917,12 +2917,19 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
"excp_to:", save->last_excp_to);
}

-static void svm_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2)
+static void svm_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2,
+ u32 *intr_info, u32 *error_code)
{
struct vmcb_control_area *control = &to_svm(vcpu)->vmcb->control;

*info1 = control->exit_info_1;
*info2 = control->exit_info_2;
+ *intr_info = control->exit_int_info;
+ if ((*intr_info & SVM_EXITINTINFO_VALID) &&
+ (*intr_info & SVM_EXITINTINFO_VALID_ERR))
+ *error_code = control->exit_int_info_err;
+ else
+ *error_code = 0;
}

static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 00e567378ae1f..4192b72c72fd8 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -248,6 +248,8 @@ TRACE_EVENT(kvm_exit,
__field( u32, isa )
__field( u64, info1 )
__field( u64, info2 )
+ __field( u32, intr_info )
+ __field( u32, error_code )
__field( unsigned int, vcpu_id )
),

@@ -257,13 +259,17 @@ TRACE_EVENT(kvm_exit,
__entry->isa = isa;
__entry->vcpu_id = vcpu->vcpu_id;
kvm_x86_ops.get_exit_info(vcpu, &__entry->info1,
- &__entry->info2);
+ &__entry->info2,
+ &__entry->intr_info,
+ &__entry->error_code);
),

- TP_printk("vcpu %u reason %s%s%s rip 0x%lx info %llx %llx",
+ TP_printk("vcpu %u reason %s%s%s rip 0x%lx info1 0x%016llx "
+ "info2 0x%016llx intr_info 0x%08x error_code 0x%08x",
__entry->vcpu_id,
kvm_print_exit_reason(__entry->exit_reason, __entry->isa),
- __entry->guest_rip, __entry->info1, __entry->info2)
+ __entry->guest_rip, __entry->info1, __entry->info2,
+ __entry->intr_info, __entry->error_code)
);

/*
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1bb59ae5016dc..c1448f42a9522 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5751,10 +5751,24 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
static const int kvm_vmx_max_exit_handlers =
ARRAY_SIZE(kvm_vmx_exit_handlers);

-static void vmx_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2)
+static void vmx_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2,
+ u32 *intr_info, u32 *error_code)
{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
*info1 = vmx_get_exit_qual(vcpu);
- *info2 = vmx_get_intr_info(vcpu);
+ if (!(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY)) {
+ *info2 = vmx->idt_vectoring_info;
+ *intr_info = vmx_get_intr_info(vcpu);
+ if (is_exception_with_error_code(*intr_info))
+ *error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
+ else
+ *error_code = 0;
+ } else {
+ *info2 = 0;
+ *intr_info = 0;
+ *error_code = 0;
+ }
}

static void vmx_destroy_pml_buffer(struct vcpu_vmx *vmx)
--
2.26.0