[PATCH v5 13/14] nEPT: Some additional comments

Gleb Natapov
2013-07-31T14:49:07Z

From: Nadav Har'El <nyh@il.ibm.com>

Some additional comments to preexisting code:
Explain who (L0 or L1) handles EPT violation and misconfiguration exits.
Don't mention "shadow on either EPT or shadow" as the only two options.

Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
---
arch/x86/kvm/vmx.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1336ec0..83d49ff 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6662,7 +6662,20 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
return nested_cpu_has2(vmcs12,
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES);
case EXIT_REASON_EPT_VIOLATION:
+ /*
+ * L0 always deals with the EPT violation. If nested EPT is
+ * used, and the nested mmu code discovers that the address is
+ * missing in the guest EPT table (EPT12), the EPT violation
+ * will be injected with nested_ept_inject_page_fault()
+ */
+ return 0;
case EXIT_REASON_EPT_MISCONFIG:
+ /*
+ * L2 never uses directly L1's EPT, but rather L0's own EPT
+ * table (shadow on EPT) or a merged EPT table that L0 built
+ * (EPT on EPT). So any problems with the structure of the
+ * table is L0's fault.
+ */
return 0;
case EXIT_REASON_PREEMPTION_TIMER:
return vmcs12->pin_based_vm_exec_control &
--
1.7.10.4