[PATCH v2 3/7] KVM: nVMX: Ignore 'hv_clean_fields' data when eVMCS data is copied in vmx_get_nested_state()

Vitaly Kuznetsov
2021-05-17T13:51:20Z

'Clean fields' data from enlightened VMCS is only valid upon vmentry: L1
hypervisor is not obliged to keep it up-to-date while it is mangling L2's
state, KVM_GET_NESTED_STATE request may come at a wrong moment when actual
eVMCS changes are unsynchronized with 'hv_clean_fields'. As upon migration
VMCS12 is used as a source of ultimate truth, we must make sure we pick all
the changes to eVMCS and thus 'clean fields' data must be ignored.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/vmx/nested.c | 49 +++++++++++++++++++++++----------------
1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ea2869d8b823..ec476f64df73 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1607,7 +1607,7 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
vmcs_load(vmx->loaded_vmcs->vmcs);
}

-static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
+static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx, u32 hv_clean_fields)
{
struct vmcs12 *vmcs12 = vmx->nested.cached_vmcs12;
struct hv_enlightened_vmcs *evmcs = vmx->nested.hv_evmcs;
@@ -1616,7 +1616,7 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
vmcs12->tpr_threshold = evmcs->tpr_threshold;
vmcs12->guest_rip = evmcs->guest_rip;

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_BASIC))) {
vmcs12->guest_rsp = evmcs->guest_rsp;
vmcs12->guest_rflags = evmcs->guest_rflags;
@@ -1624,23 +1624,23 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
evmcs->guest_interruptibility_info;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_PROC))) {
vmcs12->cpu_based_vm_exec_control =
evmcs->cpu_based_vm_exec_control;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_EXCPN))) {
vmcs12->exception_bitmap = evmcs->exception_bitmap;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_ENTRY))) {
vmcs12->vm_entry_controls = evmcs->vm_entry_controls;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_EVENT))) {
vmcs12->vm_entry_intr_info_field =
evmcs->vm_entry_intr_info_field;
@@ -1650,7 +1650,7 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
evmcs->vm_entry_instruction_len;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_HOST_GRP1))) {
vmcs12->host_ia32_pat = evmcs->host_ia32_pat;
vmcs12->host_ia32_efer = evmcs->host_ia32_efer;
@@ -1670,7 +1670,7 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
vmcs12->host_tr_selector = evmcs->host_tr_selector;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_GRP1))) {
vmcs12->pin_based_vm_exec_control =
evmcs->pin_based_vm_exec_control;
@@ -1679,18 +1679,18 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
evmcs->secondary_vm_exec_control;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_IO_BITMAP))) {
vmcs12->io_bitmap_a = evmcs->io_bitmap_a;
vmcs12->io_bitmap_b = evmcs->io_bitmap_b;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP))) {
vmcs12->msr_bitmap = evmcs->msr_bitmap;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2))) {
vmcs12->guest_es_base = evmcs->guest_es_base;
vmcs12->guest_cs_base = evmcs->guest_cs_base;
@@ -1730,14 +1730,14 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
vmcs12->guest_tr_selector = evmcs->guest_tr_selector;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_GRP2))) {
vmcs12->tsc_offset = evmcs->tsc_offset;
vmcs12->virtual_apic_page_addr = evmcs->virtual_apic_page_addr;
vmcs12->xss_exit_bitmap = evmcs->xss_exit_bitmap;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CRDR))) {
vmcs12->cr0_guest_host_mask = evmcs->cr0_guest_host_mask;
vmcs12->cr4_guest_host_mask = evmcs->cr4_guest_host_mask;
@@ -1749,7 +1749,7 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
vmcs12->guest_dr7 = evmcs->guest_dr7;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_HOST_POINTER))) {
vmcs12->host_fs_base = evmcs->host_fs_base;
vmcs12->host_gs_base = evmcs->host_gs_base;
@@ -1759,13 +1759,13 @@ static int copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx)
vmcs12->host_rsp = evmcs->host_rsp;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_XLAT))) {
vmcs12->ept_pointer = evmcs->ept_pointer;
vmcs12->virtual_processor_id = evmcs->virtual_processor_id;
}

- if (unlikely(!(evmcs->hv_clean_fields &
+ if (unlikely(!(hv_clean_fields &
HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1))) {
vmcs12->vmcs_link_pointer = evmcs->vmcs_link_pointer;
vmcs12->guest_ia32_debugctl = evmcs->guest_ia32_debugctl;
@@ -3473,6 +3473,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
enum nvmx_vmentry_status status;
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 interrupt_shadow = vmx_get_interrupt_shadow(vcpu);
+ struct hv_enlightened_vmcs *evmcs;
enum nested_evmptrld_status evmptrld_status;

++vcpu->stat.nested_run;
@@ -3488,7 +3489,8 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
return nested_vmx_failInvalid(vcpu);
}

- if (CC(!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull))
+ evmcs = vmx->nested.hv_evmcs;
+ if (CC(!evmcs && vmx->nested.current_vmptr == -1ull))
return nested_vmx_failInvalid(vcpu);

vmcs12 = get_vmcs12(vcpu);
@@ -3502,8 +3504,8 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
if (CC(vmcs12->hdr.shadow_vmcs))
return nested_vmx_failInvalid(vcpu);

- if (vmx->nested.hv_evmcs) {
- copy_enlightened_to_vmcs12(vmx);
+ if (evmcs) {
+ copy_enlightened_to_vmcs12(vmx, evmcs->hv_clean_fields);
/* Enlightened VMCS doesn't have launch state */
vmcs12->launch_state = !launch;
} else if (enable_shadow_vmcs) {
@@ -6136,7 +6138,14 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
copy_vmcs02_to_vmcs12_rare(vcpu, get_vmcs12(vcpu));
if (!vmx->nested.need_vmcs12_to_shadow_sync) {
if (vmx->nested.hv_evmcs)
- copy_enlightened_to_vmcs12(vmx);
+ /*
+ * L1 hypervisor is not obliged to keep eVMCS
+ * clean fields data always up-to-date while
+ * not in guest mode, 'hv_clean_fields' is only
+ * supposed to be actual upon vmentry so we need
+ * to ignore it here and do full copy.
+ */
+ copy_enlightened_to_vmcs12(vmx, 0);
else if (enable_shadow_vmcs)
copy_shadow_to_vmcs12(vmx);
}
--
2.31.1