On 25/10/2017 10:12, Fabian Grünbichler wrote:
> any update on this? 4.14 is soon out the door, and 4.13 with the
> breaking change just got released as part of Ubuntu 17.10 / Artful..
I had posted a patch on October 10th, but no one replied with test results.
Here is it again:
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c6ef2940119b..c29bf36485fd 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -200,6 +200,10 @@ struct loaded_vmcs {
int cpu;
bool launched;
bool nmi_known_unmasked;
+ /* Support for vnmi-less CPUs */
+ int soft_vnmi_blocked;
+ ktime_t entry_time;
+ s64 vnmi_blocked_time;
struct list_head loaded_vmcss_on_cpu_link;
};
@@ -1288,6 +1292,11 @@ static inline bool cpu_has_vmx_invpcid(void)
SECONDARY_EXEC_ENABLE_INVPCID;
}
+static inline bool cpu_has_virtual_nmis(void)
+{
+ return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;
+}
+
static inline bool cpu_has_vmx_wbinvd_exit(void)
{
return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -3678,9 +3687,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
&_vmexit_control) < 0)
return -EIO;
- min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING |
- PIN_BASED_VIRTUAL_NMIS;
- opt = PIN_BASED_POSTED_INTR | PIN_BASED_VMX_PREEMPTION_TIMER;
+ min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING;
+ opt = PIN_BASED_VIRTUAL_NMIS | PIN_BASED_POSTED_INTR |
+ PIN_BASED_VMX_PREEMPTION_TIMER;
if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PINBASED_CTLS,
&_pin_based_exec_control) < 0)
return -EIO;
@@ -5531,7 +5540,8 @@ static void enable_irq_window(struct kvm_vcpu *vcpu)
static void enable_nmi_window(struct kvm_vcpu *vcpu)
{
- if (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
+ if (!cpu_has_virtual_nmis() ||
+ vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
enable_irq_window(vcpu);
return;
}
@@ -5571,6 +5581,19 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ if (!cpu_has_virtual_nmis()) {
+ /*
+ * Tracking the NMI-blocked state in software is built upon
+ * finding the next open IRQ window. This, in turn, depends on
+ * well-behaving guests: They have to keep IRQs disabled at
+ * least as long as the NMI handler runs. Otherwise we may
+ * cause NMI nesting, maybe breaking the guest. But as this is
+ * highly unlikely, we can live with the residual risk.
+ */
+ vmx->loaded_vmcs->soft_vnmi_blocked = 1;
+ vmx->loaded_vmcs->vnmi_blocked_time = 0;
+ }
+
++vcpu->stat.nmi_injections;
vmx->loaded_vmcs->nmi_known_unmasked = false;
@@ -5589,6 +5612,8 @@ static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
bool masked;
+ if (!cpu_has_virtual_nmis())
+ return vmx->loaded_vmcs->soft_vnmi_blocked;
if (vmx->loaded_vmcs->nmi_known_unmasked)
return false;
masked = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_NMI;
@@ -5600,13 +5625,20 @@ static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- vmx->loaded_vmcs->nmi_known_unmasked = !masked;
- if (masked)
- vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
- GUEST_INTR_STATE_NMI);
- else
- vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
- GUEST_INTR_STATE_NMI);
+ if (!cpu_has_virtual_nmis()) {
+ if (vmx->loaded_vmcs->soft_vnmi_blocked != masked) {
+ vmx->loaded_vmcs->soft_vnmi_blocked = masked;
+ vmx->loaded_vmcs->vnmi_blocked_time = 0;
+ }
+ } else {
+ vmx->loaded_vmcs->nmi_known_unmasked = !masked;
+ if (masked)
+ vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
+ GUEST_INTR_STATE_NMI);
+ else
+ vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
+ GUEST_INTR_STATE_NMI);
+ }
}
static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
@@ -5614,6 +5646,10 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
if (to_vmx(vcpu)->nested.nested_run_pending)
return 0;
+ if (!cpu_has_virtual_nmis() &&
+ to_vmx(vcpu)->loaded_vmcs->soft_vnmi_blocked)
+ return 0;
+
return !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
(GUEST_INTR_STATE_MOV_SS | GUEST_INTR_STATE_STI
| GUEST_INTR_STATE_NMI));
@@ -6341,6 +6377,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
* AAK134, BY25.
*/
if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
+ cpu_has_virtual_nmis() &&
(exit_qualification & INTR_INFO_UNBLOCK_NMI))
vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
@@ -6813,7 +6850,7 @@ static struct loaded_vmcs *nested_get_current_vmcs02(struct vcpu_vmx *vmx)
}
/* Create a new VMCS */
- item = kmalloc(sizeof(struct vmcs02_list), GFP_KERNEL);
+ item = kzalloc(sizeof(struct vmcs02_list), GFP_KERNEL);
if (!item)
return NULL;
item->vmcs02.vmcs = alloc_vmcs();
@@ -7830,6 +7867,7 @@ static int handle_pml_full(struct kvm_vcpu *vcpu)
* "blocked by NMI" bit has to be set before next VM entry.
*/
if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
+ cpu_has_virtual_nmis() &&
(exit_qualification & INTR_INFO_UNBLOCK_NMI))
vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
GUEST_INTR_STATE_NMI);
@@ -8547,6 +8585,25 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
return 0;
}
+ if (unlikely(!cpu_has_virtual_nmis() &&
+ vmx->loaded_vmcs->soft_vnmi_blocked)) {
+ if (vmx_interrupt_allowed(vcpu)) {
+ vmx->loaded_vmcs->soft_vnmi_blocked = 0;
+ } else if (vmx->loaded_vmcs->vnmi_blocked_time > 1000000000LL &&
+ vcpu->arch.nmi_pending) {
+ /*
+ * This CPU don't support us in finding the end of an
+ * NMI-blocked window if the guest runs with IRQs
+ * disabled. So we pull the trigger after 1 s of
+ * futile waiting, but inform the user about this.
+ */
+ printk(KERN_WARNING "%s: Breaking out of NMI-blocked "
+ "state on VCPU %d after 1 s timeout\n",
+ __func__, vcpu->vcpu_id);
+ vmx->loaded_vmcs->soft_vnmi_blocked = 0;
+ }
+ }
+
if (exit_reason < kvm_vmx_max_exit_handlers
&& kvm_vmx_exit_handlers[exit_reason])
return kvm_vmx_exit_handlers[exit_reason](vcpu);
@@ -8830,33 +8887,38 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
idtv_info_valid = vmx->idt_vectoring_info & VECTORING_INFO_VALID_MASK;
- if (vmx->loaded_vmcs->nmi_known_unmasked)
- return;
- /*
- * Can't use vmx->exit_intr_info since we're not sure what
- * the exit reason is.
- */
- exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
- unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0;
- vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
- /*
- * SDM 3: 27.7.1.2 (September 2008)
- * Re-set bit "block by NMI" before VM entry if vmexit caused by
- * a guest IRET fault.
- * SDM 3: 23.2.2 (September 2008)
- * Bit 12 is undefined in any of the following cases:
- * If the VM exit sets the valid bit in the IDT-vectoring
- * information field.
- * If the VM exit is due to a double fault.
- */
- if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi &&
- vector != DF_VECTOR && !idtv_info_valid)
- vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
- GUEST_INTR_STATE_NMI);
- else
- vmx->loaded_vmcs->nmi_known_unmasked =
- !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO)
- & GUEST_INTR_STATE_NMI);
+ if (cpu_has_virtual_nmis()) {
+ if (vmx->loaded_vmcs->nmi_known_unmasked)
+ return;
+ /*
+ * Can't use vmx->exit_intr_info since we're not sure what
+ * the exit reason is.
+ */
+ exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
+ unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0;
+ vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
+ /*
+ * SDM 3: 27.7.1.2 (September 2008)
+ * Re-set bit "block by NMI" before VM entry if vmexit caused by
+ * a guest IRET fault.
+ * SDM 3: 23.2.2 (September 2008)
+ * Bit 12 is undefined in any of the following cases:
+ * If the VM exit sets the valid bit in the IDT-vectoring
+ * information field.
+ * If the VM exit is due to a double fault.
+ */
+ if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi &&
+ vector != DF_VECTOR && !idtv_info_valid)
+ vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
+ GUEST_INTR_STATE_NMI);
+ else
+ vmx->loaded_vmcs->nmi_known_unmasked =
+ !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO)
+ & GUEST_INTR_STATE_NMI);
+ } else if (unlikely(vmx->loaded_vmcs->soft_vnmi_blocked))
+ vmx->loaded_vmcs->vnmi_blocked_time +=
+ ktime_to_ns(ktime_sub(ktime_get(),
+ vmx->loaded_vmcs->entry_time));
}
static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
@@ -8973,6 +9035,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long debugctlmsr, cr3, cr4;
+ /* Record the guest's net vcpu time for enforced NMI injections. */
+ if (unlikely(!cpu_has_virtual_nmis() &&
+ vmx->loaded_vmcs->soft_vnmi_blocked))
+ vmx->loaded_vmcs->entry_time = ktime_get();
+
/* Don't enter VMX if guest state is invalid, let the exit handler
start emulation until we arrive back to a valid state */
if (vmx->emulation_required)
