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Subject[PATCH] KVM: nVMX: remove side effects from nested_vmx_exit_reflected
Date
The name of nested_vmx_exit_reflected suggests that it's purely
a test, but it actually marks VMCS12 pages as dirty. Move this to
vmx_handle_exit, observing that the initial nested_run_pending check in
nested_vmx_exit_reflected is pointless---nested_run_pending has just
been cleared in vmx_vcpu_run and won't be set until handle_vmlaunch
or handle_vmresume.

Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/nested.c | 18 ++----------------
arch/x86/kvm/vmx/nested.h | 1 +
arch/x86/kvm/vmx/vmx.c | 19 +++++++++++++++++--
3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8578513907d7..4ff859c99946 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3527,7 +3527,7 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
}


-static void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu)
+void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
gfn_t gfn;
@@ -5543,8 +5543,7 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);

- if (vmx->nested.nested_run_pending)
- return false;
+ WARN_ON_ONCE(vmx->nested.nested_run_pending);

if (unlikely(vmx->fail)) {
trace_kvm_nested_vmenter_failed(
@@ -5553,19 +5552,6 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
return true;
}

- /*
- * The host physical addresses of some pages of guest memory
- * are loaded into the vmcs02 (e.g. vmcs12's Virtual APIC
- * Page). The CPU may write to these pages via their host
- * physical address while L2 is running, bypassing any
- * address-translation-based dirty tracking (e.g. EPT write
- * protection).
- *
- * Mark them dirty on every exit from L2 to prevent them from
- * getting out of sync with dirty tracking.
- */
- nested_mark_vmcs12_pages_dirty(vcpu);
-
trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason,
vmcs_readl(EXIT_QUALIFICATION),
vmx->idt_vectoring_info,
diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index 21d36652f213..f70968b76d33 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -33,6 +33,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
u32 vmx_instruction_info, bool wr, int len, gva_t *ret);
void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu);
+void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu);
bool nested_vmx_check_io_bitmaps(struct kvm_vcpu *vcpu, unsigned int port,
int size);

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b447d66f44e6..07299a957d4a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5851,8 +5851,23 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
if (vmx->emulation_required)
return handle_invalid_guest_state(vcpu);

- if (is_guest_mode(vcpu) && nested_vmx_exit_reflected(vcpu, exit_reason))
- return nested_vmx_reflect_vmexit(vcpu, exit_reason);
+ if (is_guest_mode(vcpu)) {
+ /*
+ * The host physical addresses of some pages of guest memory
+ * are loaded into the vmcs02 (e.g. vmcs12's Virtual APIC
+ * Page). The CPU may write to these pages via their host
+ * physical address while L2 is running, bypassing any
+ * address-translation-based dirty tracking (e.g. EPT write
+ * protection).
+ *
+ * Mark them dirty on every exit from L2 to prevent them from
+ * getting out of sync with dirty tracking.
+ */
+ nested_mark_vmcs12_pages_dirty(vcpu);
+
+ if (nested_vmx_exit_reflected(vcpu, exit_reason))
+ return nested_vmx_reflect_vmexit(vcpu, exit_reason);
+ }

if (exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) {
dump_vmcs();
--
1.8.3.1
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