[PATCH v7 077/102] KVM: TDX: Implement interrupt injection

isaku.yamahata
2022-06-27T21:57:49Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

TDX supports interrupt inject into vcpu with posted interrupt. Wire up the
corresponding kvm x86 operations to posted interrupt. Move
kvm_vcpu_trigger_posted_interrupt() from vmx.c to common.h to share the
code.

VMX can inject interrupt by setting interrupt information field,
VM_ENTRY_INTR_INFO_FIELD, of VMCS. TDX supports interrupt injection only
by posted interrupt. Ignore the execution path to access
VM_ENTRY_INTR_INFO_FIELD.

As cpu state is protected and apicv is enabled for the TDX guest, VMM can
inject interrupt by updating posted interrupt descriptor. Treat interrupt
can be injected always.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/common.h | 71 ++++++++++++++++++++++++++
arch/x86/kvm/vmx/main.c | 92 ++++++++++++++++++++++++++++++----
arch/x86/kvm/vmx/posted_intr.c | 2 +-
arch/x86/kvm/vmx/posted_intr.h | 2 +
arch/x86/kvm/vmx/tdx.c | 25 +++++++++
arch/x86/kvm/vmx/vmx.c | 67 +------------------------
arch/x86/kvm/vmx/x86_ops.h | 7 ++-
7 files changed, 189 insertions(+), 77 deletions(-)

diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index 235908f3e044..1522e9e6851b 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -4,6 +4,7 @@

#include <linux/kvm_host.h>

+#include "posted_intr.h"
#include "mmu.h"

static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
@@ -30,4 +31,74 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
}

+static inline void kvm_vcpu_trigger_posted_interrupt(struct kvm_vcpu *vcpu,
+ int pi_vec)
+{
+#ifdef CONFIG_SMP
+ if (vcpu->mode == IN_GUEST_MODE) {
+ /*
+ * The vector of the virtual has already been set in the PIR.
+ * Send a notification event to deliver the virtual interrupt
+ * unless the vCPU is the currently running vCPU, i.e. the
+ * event is being sent from a fastpath VM-Exit handler, in
+ * which case the PIR will be synced to the vIRR before
+ * re-entering the guest.
+ *
+ * When the target is not the running vCPU, the following
+ * possibilities emerge:
+ *
+ * Case 1: vCPU stays in non-root mode. Sending a notification
+ * event posts the interrupt to the vCPU.
+ *
+ * Case 2: vCPU exits to root mode and is still runnable. The
+ * PIR will be synced to the vIRR before re-entering the guest.
+ * Sending a notification event is ok as the host IRQ handler
+ * will ignore the spurious event.
+ *
+ * Case 3: vCPU exits to root mode and is blocked. vcpu_block()
+ * has already synced PIR to vIRR and never blocks the vCPU if
+ * the vIRR is not empty. Therefore, a blocked vCPU here does
+ * not wait for any requested interrupts in PIR, and sending a
+ * notification event also results in a benign, spurious event.
+ */
+
+ if (vcpu != kvm_get_running_vcpu())
+ apic->send_IPI_mask(get_cpu_mask(vcpu->cpu), pi_vec);
+ return;
+ }
+#endif
+ /*
+ * The vCPU isn't in the guest; wake the vCPU in case it is blocking,
+ * otherwise do nothing as KVM will grab the highest priority pending
+ * IRQ via ->sync_pir_to_irr() in vcpu_enter_guest().
+ */
+ kvm_vcpu_wake_up(vcpu);
+}
+
+/*
+ * Send interrupt to vcpu via posted interrupt way.
+ * 1. If target vcpu is running(non-root mode), send posted interrupt
+ * notification to vcpu and hardware will sync PIR to vIRR atomically.
+ * 2. If target vcpu isn't running(root mode), kick it to pick up the
+ * interrupt from PIR in next vmentry.
+ */
+static inline void __vmx_deliver_posted_interrupt(
+ struct kvm_vcpu *vcpu, struct pi_desc *pi_desc, int vector)
+{
+ if (pi_test_and_set_pir(vector, pi_desc))
+ return;
+
+ /* If a previous notification has sent the IPI, nothing to do. */
+ if (pi_test_and_set_on(pi_desc))
+ return;
+
+ /*
+ * The implied barrier in pi_test_and_set_on() pairs with the smp_mb_*()
+ * after setting vcpu->mode in vcpu_enter_guest(), thus the vCPU is
+ * guaranteed to see PID.ON=1 and sync the PIR to IRR if triggering a
+ * posted interrupt "fails" because vcpu->mode != IN_GUEST_MODE.
+ */
+ kvm_vcpu_trigger_posted_interrupt(vcpu, POSTED_INTR_VECTOR);
+}
+
#endif /* __KVM_X86_VMX_COMMON_H */
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index f14519c6a861..07ea7211c633 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -188,6 +188,33 @@ static bool vt_protected_apic_has_interrupt(struct kvm_vcpu *vcpu)
return tdx_protected_apic_has_interrupt(vcpu);
}

+static void vt_apicv_post_state_restore(struct kvm_vcpu *vcpu)
+{
+ struct pi_desc *pi = vcpu_to_pi_desc(vcpu);
+ pi_clear_on(pi);
+ memset(pi->pir, 0, sizeof(pi->pir));
+}
+
+static int vt_sync_pir_to_irr(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu))
+ return -1;
+
+ return vmx_sync_pir_to_irr(vcpu);
+}
+
+static void vt_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
+ int trig_mode, int vector)
+{
+ if (is_td_vcpu(apic->vcpu)) {
+ tdx_deliver_interrupt(apic, delivery_mode, trig_mode,
+ vector);
+ return;
+ }
+
+ vmx_deliver_interrupt(apic, delivery_mode, trig_mode, vector);
+}
+
static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
{
if (is_td_vcpu(vcpu))
@@ -237,6 +264,53 @@ static void vt_sched_in(struct kvm_vcpu *vcpu, int cpu)
vmx_sched_in(vcpu, cpu);
}

+static void vt_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
+{
+ if (is_td_vcpu(vcpu))
+ return;
+ vmx_set_interrupt_shadow(vcpu, mask);
+}
+
+static u32 vt_get_interrupt_shadow(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu))
+ return 0;
+
+ return vmx_get_interrupt_shadow(vcpu);
+}
+
+static void vt_inject_irq(struct kvm_vcpu *vcpu, bool reinjected)
+{
+ if (is_td_vcpu(vcpu))
+ return;
+
+ vmx_inject_irq(vcpu, reinjected);
+}
+
+static void vt_cancel_injection(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu))
+ return;
+
+ vmx_cancel_injection(vcpu);
+}
+
+static int vt_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)
+{
+ if (is_td_vcpu(vcpu))
+ return true;
+
+ return vmx_interrupt_allowed(vcpu, for_injection);
+}
+
+static void vt_enable_irq_window(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu))
+ return;
+
+ vmx_enable_irq_window(vcpu);
+}
+
static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
{
if (!is_td(kvm))
@@ -313,31 +387,31 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.handle_exit = vmx_handle_exit,
.skip_emulated_instruction = vmx_skip_emulated_instruction,
.update_emulated_instruction = vmx_update_emulated_instruction,
- .set_interrupt_shadow = vmx_set_interrupt_shadow,
- .get_interrupt_shadow = vmx_get_interrupt_shadow,
+ .set_interrupt_shadow = vt_set_interrupt_shadow,
+ .get_interrupt_shadow = vt_get_interrupt_shadow,
.patch_hypercall = vmx_patch_hypercall,
- .inject_irq = vmx_inject_irq,
+ .inject_irq = vt_inject_irq,
.inject_nmi = vmx_inject_nmi,
.queue_exception = vmx_queue_exception,
- .cancel_injection = vmx_cancel_injection,
- .interrupt_allowed = vmx_interrupt_allowed,
+ .cancel_injection = vt_cancel_injection,
+ .interrupt_allowed = vt_interrupt_allowed,
.nmi_allowed = vmx_nmi_allowed,
.get_nmi_mask = vmx_get_nmi_mask,
.set_nmi_mask = vmx_set_nmi_mask,
.enable_nmi_window = vmx_enable_nmi_window,
- .enable_irq_window = vmx_enable_irq_window,
+ .enable_irq_window = vt_enable_irq_window,
.update_cr8_intercept = vmx_update_cr8_intercept,
.set_virtual_apic_mode = vmx_set_virtual_apic_mode,
.set_apic_access_page_addr = vmx_set_apic_access_page_addr,
.refresh_apicv_exec_ctrl = vmx_refresh_apicv_exec_ctrl,
.load_eoi_exitmap = vmx_load_eoi_exitmap,
- .apicv_post_state_restore = vmx_apicv_post_state_restore,
+ .apicv_post_state_restore = vt_apicv_post_state_restore,
.check_apicv_inhibit_reasons = vmx_check_apicv_inhibit_reasons,
.hwapic_irr_update = vmx_hwapic_irr_update,
.hwapic_isr_update = vmx_hwapic_isr_update,
.guest_apic_has_interrupt = vmx_guest_apic_has_interrupt,
- .sync_pir_to_irr = vmx_sync_pir_to_irr,
- .deliver_interrupt = vmx_deliver_interrupt,
+ .sync_pir_to_irr = vt_sync_pir_to_irr,
+ .deliver_interrupt = vt_deliver_interrupt,
.dy_apicv_has_pending_interrupt = pi_has_pending_interrupt,
.protected_apic_has_interrupt = vt_protected_apic_has_interrupt,

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 196bf9f86ee4..86c5bc9255c5 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -50,7 +50,7 @@ static inline struct vcpu_pi *vcpu_to_pi(struct kvm_vcpu *vcpu)
return (struct vcpu_pi*)vcpu;
}

-static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
+struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
{
return &vcpu_to_pi(vcpu)->pi_desc;
}
diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h
index 2fe8222308b2..0f9983b6910b 100644
--- a/arch/x86/kvm/vmx/posted_intr.h
+++ b/arch/x86/kvm/vmx/posted_intr.h
@@ -105,6 +105,8 @@ struct vcpu_pi {
/* Until here common layout betwwn vcpu_vmx and vcpu_tdx. */
};

+struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu);
+
void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu);
void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu);
void pi_wakeup_handler(void);
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 01dd2376c3a1..db3840c040f9 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -7,6 +7,7 @@

#include "capabilities.h"
#include "x86_ops.h"
+#include "common.h"
#include "mmu.h"
#include "tdx.h"
#include "vmx.h"
@@ -556,6 +557,9 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.guest_state_protected =
!(to_kvm_tdx(vcpu->kvm)->attributes & TDX_TD_ATTRIBUTE_DEBUG);

+ tdx->pi_desc.nv = POSTED_INTR_VECTOR;
+ tdx->pi_desc.sn = 1;
+
tdx->host_state_need_save = true;
tdx->host_state_need_restore = false;

@@ -576,6 +580,7 @@ void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_tdx *tdx = to_tdx(vcpu);

+ vmx_vcpu_pi_load(vcpu, cpu);
if (vcpu->cpu == cpu)
return;

@@ -789,6 +794,12 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)

trace_kvm_entry(vcpu);

+ if (pi_test_on(&tdx->pi_desc)) {
+ apic->send_IPI_self(POSTED_INTR_VECTOR);
+
+ kvm_wait_lapic_expire(vcpu);
+ }
+
tdx_vcpu_enter_exit(vcpu, tdx);

tdx_user_return_update_cache();
@@ -1126,6 +1137,16 @@ static void tdx_handle_changed_private_spte(
}
}

+void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
+ int trig_mode, int vector)
+{
+ struct kvm_vcpu *vcpu = apic->vcpu;
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+
+ /* TDX supports only posted interrupt. No lapic emulation. */
+ __vmx_deliver_posted_interrupt(vcpu, &tdx->pi_desc, vector);
+}
+
int tdx_dev_ioctl(void __user *argp)
{
struct kvm_tdx_capabilities __user *user_caps;
@@ -1562,6 +1583,10 @@ int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp)
return -EIO;
}

+ td_vmcs_write16(tdx, POSTED_INTR_NV, POSTED_INTR_VECTOR);
+ td_vmcs_write64(tdx, POSTED_INTR_DESC_ADDR, __pa(&tdx->pi_desc));
+ td_vmcs_setbit32(tdx, PIN_BASED_VM_EXEC_CONTROL, PIN_BASED_POSTED_INTR);
+
tdx->initialized = true;
return 0;
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3f231159fe3d..3aca3976ba1b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4010,50 +4010,6 @@ void vmx_msr_filter_changed(struct kvm_vcpu *vcpu)
pt_update_intercept_for_msr(vcpu);
}

-static inline void kvm_vcpu_trigger_posted_interrupt(struct kvm_vcpu *vcpu,
- int pi_vec)
-{
-#ifdef CONFIG_SMP
- if (vcpu->mode == IN_GUEST_MODE) {
- /*
- * The vector of the virtual has already been set in the PIR.
- * Send a notification event to deliver the virtual interrupt
- * unless the vCPU is the currently running vCPU, i.e. the
- * event is being sent from a fastpath VM-Exit handler, in
- * which case the PIR will be synced to the vIRR before
- * re-entering the guest.
- *
- * When the target is not the running vCPU, the following
- * possibilities emerge:
- *
- * Case 1: vCPU stays in non-root mode. Sending a notification
- * event posts the interrupt to the vCPU.
- *
- * Case 2: vCPU exits to root mode and is still runnable. The
- * PIR will be synced to the vIRR before re-entering the guest.
- * Sending a notification event is ok as the host IRQ handler
- * will ignore the spurious event.
- *
- * Case 3: vCPU exits to root mode and is blocked. vcpu_block()
- * has already synced PIR to vIRR and never blocks the vCPU if
- * the vIRR is not empty. Therefore, a blocked vCPU here does
- * not wait for any requested interrupts in PIR, and sending a
- * notification event also results in a benign, spurious event.
- */
-
- if (vcpu != kvm_get_running_vcpu())
- apic->send_IPI_mask(get_cpu_mask(vcpu->cpu), pi_vec);
- return;
- }
-#endif
- /*
- * The vCPU isn't in the guest; wake the vCPU in case it is blocking,
- * otherwise do nothing as KVM will grab the highest priority pending
- * IRQ via ->sync_pir_to_irr() in vcpu_enter_guest().
- */
- kvm_vcpu_wake_up(vcpu);
-}
-
static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
int vector)
{
@@ -4105,20 +4061,7 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
if (!vcpu->arch.apicv_active)
return -1;

- if (pi_test_and_set_pir(vector, &vmx->pi_desc))
- return 0;
-
- /* If a previous notification has sent the IPI, nothing to do. */
- if (pi_test_and_set_on(&vmx->pi_desc))
- return 0;
-
- /*
- * The implied barrier in pi_test_and_set_on() pairs with the smp_mb_*()
- * after setting vcpu->mode in vcpu_enter_guest(), thus the vCPU is
- * guaranteed to see PID.ON=1 and sync the PIR to IRR if triggering a
- * posted interrupt "fails" because vcpu->mode != IN_GUEST_MODE.
- */
- kvm_vcpu_trigger_posted_interrupt(vcpu, POSTED_INTR_VECTOR);
+ __vmx_deliver_posted_interrupt(vcpu, &vmx->pi_desc, vector);
return 0;
}

@@ -6702,14 +6645,6 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
vmcs_write64(EOI_EXIT_BITMAP3, eoi_exit_bitmap[3]);
}

-void vmx_apicv_post_state_restore(struct kvm_vcpu *vcpu)
-{
- struct vcpu_vmx *vmx = to_vmx(vcpu);
-
- pi_clear_on(&vmx->pi_desc);
- memset(vmx->pi_desc.pir, 0, sizeof(vmx->pi_desc.pir));
-}
-
void vmx_do_interrupt_nmi_irqoff(unsigned long entry);

static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 17aaa0b3d921..bc25260aefc6 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -53,7 +53,6 @@ int vmx_check_intercept(struct kvm_vcpu *vcpu,
bool vmx_apic_init_signal_blocked(struct kvm_vcpu *vcpu);
void vmx_migrate_timers(struct kvm_vcpu *vcpu);
void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
-void vmx_apicv_post_state_restore(struct kvm_vcpu *vcpu);
bool vmx_check_apicv_inhibit_reasons(enum kvm_apicv_inhibit reason);
void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr);
void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr);
@@ -149,6 +148,9 @@ void tdx_vcpu_put(struct kvm_vcpu *vcpu);
void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
bool tdx_protected_apic_has_interrupt(struct kvm_vcpu *vcpu);

+void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
+ int trig_mode, int vector);
+
int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);

@@ -176,6 +178,9 @@ static inline void tdx_vcpu_put(struct kvm_vcpu *vcpu) {}
static inline void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {}
static inline bool tdx_protected_apic_has_interrupt(struct kvm_vcpu *vcpu) { return false; }

+static inline void tdx_deliver_interrupt(
+ struct kvm_lapic *apic, int delivery_mode, int trig_mode, int vector) {}
+
static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }

--
2.25.1