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Subject[PATCH v6 11/13] x86/kvm/nVMX: nested state migration for Enlightened VMCS
Date
Add support for get/set of nested state when Enlightened VMCS is in use.
A new KVM_STATE_NESTED_EVMCS flag to indicate eVMCS on the vCPU was enabled
is added.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/include/uapi/asm/kvm.h | 1 +
arch/x86/kvm/vmx.c | 78 +++++++++++++++++++++++++--------
arch/x86/kvm/x86.c | 6 ++-
3 files changed, 65 insertions(+), 20 deletions(-)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index fd23d5778ea1..ab76aa1d3a4d 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -381,6 +381,7 @@ struct kvm_sync_regs {

#define KVM_STATE_NESTED_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
+#define KVM_STATE_NESTED_EVMCS 0x00000004

#define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_SMM_VMXON 0x00000002
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5df47291ad4d..8d7c60faaacd 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1618,7 +1618,8 @@ static int nested_enable_evmcs(struct kvm_vcpu *vcpu,
* maximum supported version. KVM supports versions from 1 to
* KVM_EVMCS_VERSION.
*/
- *vmcs_version = (KVM_EVMCS_VERSION << 8) | 1;
+ if (vmcs_version)
+ *vmcs_version = (KVM_EVMCS_VERSION << 8) | 1;

vmx->nested.msrs.pinbased_ctls_high &= ~EVMCS1_UNSUPPORTED_PINCTRL;
vmx->nested.msrs.entry_ctls_high &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
@@ -9338,7 +9339,8 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
* This is an equivalent of the nested hypervisor executing the vmptrld
* instruction.
*/
-static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu)
+static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu,
+ bool from_launch)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct hv_vp_assist_page assist_page;
@@ -9389,8 +9391,9 @@ static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu)
* present in struct hv_enlightened_vmcs, ...). Make sure there
* are no leftovers.
*/
- memset(vmx->nested.cached_vmcs12, 0,
- sizeof(*vmx->nested.cached_vmcs12));
+ if (from_launch)
+ memset(vmx->nested.cached_vmcs12, 0,
+ sizeof(*vmx->nested.cached_vmcs12));

}
return 1;
@@ -11147,6 +11150,15 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
}

if (vmx->nested.need_vmcs12_sync) {
+ /*
+ * hv_evmcs may end up being not mapped after migration (when
+ * L2 was running), map it here to make sure vmcs12 changes are
+ * properly reflected.
+ */
+ if (vmx->nested.enlightened_vmcs_enabled &&
+ !vmx->nested.hv_evmcs)
+ nested_vmx_handle_enlightened_vmptrld(vcpu, false);
+
if (vmx->nested.hv_evmcs) {
copy_vmcs12_to_enlightened(vmx);
/* All fields are clean */
@@ -13424,7 +13436,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
if (!nested_vmx_check_permission(vcpu))
return 1;

- if (!nested_vmx_handle_enlightened_vmptrld(vcpu))
+ if (!nested_vmx_handle_enlightened_vmptrld(vcpu, true))
return 1;

if (!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull)
@@ -14711,6 +14723,20 @@ static int enable_smi_window(struct kvm_vcpu *vcpu)
return 0;
}

+static inline int vmx_has_valid_vmcs12(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ /*
+ * In case we do two consecutive get/set_nested_state()s while L2 was
+ * running hv_evmcs may end up not being mapped (we map it from
+ * nested_vmx_run()/vmx_vcpu_run()). Check is_guest_mode() as we always
+ * have vmcs12 if it is true.
+ */
+ return is_guest_mode(vcpu) || vmx->nested.current_vmptr != -1ull ||
+ vmx->nested.hv_evmcs;
+}
+
static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
struct kvm_nested_state __user *user_kvm_nested_state,
u32 user_data_size)
@@ -14731,16 +14757,15 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
vmx = to_vmx(vcpu);
vmcs12 = get_vmcs12(vcpu);

- /* FIXME: Enlightened VMCS is currently unsupported */
- if (vmx->nested.hv_evmcs)
- return -ENOTSUPP;
+ if (nested_vmx_allowed(vcpu) && vmx->nested.enlightened_vmcs_enabled)
+ kvm_state.flags |= KVM_STATE_NESTED_EVMCS;

if (nested_vmx_allowed(vcpu) &&
(vmx->nested.vmxon || vmx->nested.smm.vmxon)) {
kvm_state.vmx.vmxon_pa = vmx->nested.vmxon_ptr;
kvm_state.vmx.vmcs_pa = vmx->nested.current_vmptr;

- if (vmx->nested.current_vmptr != -1ull) {
+ if (vmx_has_valid_vmcs12(vcpu)) {
kvm_state.size += VMCS12_SIZE;

if (is_guest_mode(vcpu) &&
@@ -14769,20 +14794,24 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
if (copy_to_user(user_kvm_nested_state, &kvm_state, sizeof(kvm_state)))
return -EFAULT;

- if (vmx->nested.current_vmptr == -1ull)
+ if (!vmx_has_valid_vmcs12(vcpu))
goto out;

/*
* When running L2, the authoritative vmcs12 state is in the
* vmcs02. When running L1, the authoritative vmcs12 state is
- * in the shadow vmcs linked to vmcs01, unless
+ * in the shadow or enlightened vmcs linked to vmcs01, unless
* need_vmcs12_sync is set, in which case, the authoritative
* vmcs12 state is in the vmcs12 already.
*/
- if (is_guest_mode(vcpu))
+ if (is_guest_mode(vcpu)) {
sync_vmcs12(vcpu, vmcs12);
- else if (enable_shadow_vmcs && !vmx->nested.need_vmcs12_sync)
- copy_shadow_to_vmcs12(vmx);
+ } else if (!vmx->nested.need_vmcs12_sync) {
+ if (vmx->nested.hv_evmcs)
+ copy_enlightened_to_vmcs12(vmx);
+ else if (enable_shadow_vmcs)
+ copy_shadow_to_vmcs12(vmx);
+ }

if (copy_to_user(user_kvm_nested_state->data, vmcs12, sizeof(*vmcs12)))
return -EFAULT;
@@ -14810,6 +14839,9 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
if (kvm_state->format != 0)
return -EINVAL;

+ if (kvm_state->flags & KVM_STATE_NESTED_EVMCS)
+ nested_enable_evmcs(vcpu, NULL);
+
if (!nested_vmx_allowed(vcpu))
return kvm_state->vmx.vmxon_pa == -1ull ? 0 : -EINVAL;

@@ -14860,11 +14892,21 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
if (kvm_state->size < sizeof(kvm_state) + sizeof(*vmcs12))
return 0;

- if (kvm_state->vmx.vmcs_pa == kvm_state->vmx.vmxon_pa ||
- !page_address_valid(vcpu, kvm_state->vmx.vmcs_pa))
- return -EINVAL;
+ if (kvm_state->vmx.vmcs_pa != -1ull) {
+ if (kvm_state->vmx.vmcs_pa == kvm_state->vmx.vmxon_pa ||
+ !page_address_valid(vcpu, kvm_state->vmx.vmcs_pa))
+ return -EINVAL;

- set_current_vmptr(vmx, kvm_state->vmx.vmcs_pa);
+ set_current_vmptr(vmx, kvm_state->vmx.vmcs_pa);
+ } else if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) {
+ /*
+ * Sync eVMCS upon entry as we may not have
+ * HV_X64_MSR_VP_ASSIST_PAGE set up yet.
+ */
+ vmx->nested.need_vmcs12_sync = true;
+ } else {
+ return -EINVAL;
+ }

if (kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON) {
vmx->nested.smm.vmxon = true;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 50f308499ce5..0fe1e3762e82 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4068,11 +4068,13 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
break;

if (kvm_state.flags &
- ~(KVM_STATE_NESTED_RUN_PENDING | KVM_STATE_NESTED_GUEST_MODE))
+ ~(KVM_STATE_NESTED_RUN_PENDING | KVM_STATE_NESTED_GUEST_MODE
+ | KVM_STATE_NESTED_EVMCS))
break;

/* nested_run_pending implies guest_mode. */
- if (kvm_state.flags == KVM_STATE_NESTED_RUN_PENDING)
+ if ((kvm_state.flags & KVM_STATE_NESTED_RUN_PENDING)
+ && !(kvm_state.flags & KVM_STATE_NESTED_GUEST_MODE))
break;

r = kvm_x86_ops->set_nested_state(vcpu, user_kvm_nested_state, &kvm_state);
--
2.17.1
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