1 files changed, 92 insertions, 47 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a7172ba59ad2..95c6beb8ce27 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -351,10 +351,8 @@ static void kvm_recalculate_logical_map(struct kvm_apic_map *new,
 	 * reversing the LDR calculation to get cluster of APICs, i.e. no
 	 * additional work is required.
 	 */
-	if (apic_x2apic_mode(apic)) {
-		WARN_ON_ONCE(ldr != kvm_apic_calc_x2apic_ldr(kvm_x2apic_id(apic)));
+	if (apic_x2apic_mode(apic))
 		return;
-	}
 
 	if (WARN_ON_ONCE(!kvm_apic_map_get_logical_dest(new, ldr,
 							&cluster, &mask))) {
@@ -1743,7 +1741,7 @@ static void limit_periodic_timer_frequency(struct kvm_lapic *apic)
 		s64 min_period = min_timer_period_us * 1000LL;
 
 		if (apic->lapic_timer.period < min_period) {
-			pr_info_ratelimited(
+			pr_info_once(
 			    "vcpu %i: requested %lld ns "
 			    "lapic timer period limited to %lld ns\n",
 			    apic->vcpu->vcpu_id,
@@ -1946,7 +1944,7 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
 	u64 ns = 0;
 	ktime_t expire;
 	struct kvm_vcpu *vcpu = apic->vcpu;
-	unsigned long this_tsc_khz = vcpu->arch.virtual_tsc_khz;
+	u32 this_tsc_khz = vcpu->arch.virtual_tsc_khz;
 	unsigned long flags;
 	ktime_t now;
 
@@ -2455,6 +2453,43 @@ void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi);
 
+#define X2APIC_ICR_RESERVED_BITS (GENMASK_ULL(31, 20) | GENMASK_ULL(17, 16) | BIT(13))
+
+int kvm_x2apic_icr_write(struct kvm_lapic *apic, u64 data)
+{
+	if (data & X2APIC_ICR_RESERVED_BITS)
+		return 1;
+
+	/*
+	 * The BUSY bit is reserved on both Intel and AMD in x2APIC mode, but
+	 * only AMD requires it to be zero, Intel essentially just ignores the
+	 * bit.  And if IPI virtualization (Intel) or x2AVIC (AMD) is enabled,
+	 * the CPU performs the reserved bits checks, i.e. the underlying CPU
+	 * behavior will "win".  Arbitrarily clear the BUSY bit, as there is no
+	 * sane way to provide consistent behavior with respect to hardware.
+	 */
+	data &= ~APIC_ICR_BUSY;
+
+	kvm_apic_send_ipi(apic, (u32)data, (u32)(data >> 32));
+	if (kvm_x86_ops.x2apic_icr_is_split) {
+		kvm_lapic_set_reg(apic, APIC_ICR, data);
+		kvm_lapic_set_reg(apic, APIC_ICR2, data >> 32);
+	} else {
+		kvm_lapic_set_reg64(apic, APIC_ICR, data);
+	}
+	trace_kvm_apic_write(APIC_ICR, data);
+	return 0;
+}
+
+static u64 kvm_x2apic_icr_read(struct kvm_lapic *apic)
+{
+	if (kvm_x86_ops.x2apic_icr_is_split)
+		return (u64)kvm_lapic_get_reg(apic, APIC_ICR) |
+		       (u64)kvm_lapic_get_reg(apic, APIC_ICR2) << 32;
+
+	return kvm_lapic_get_reg64(apic, APIC_ICR);
+}
+
 /* emulate APIC access in a trap manner */
 void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset)
 {
@@ -2472,7 +2507,7 @@ void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset)
 	 * maybe-unecessary write, and both are in the noise anyways.
 	 */
 	if (apic_x2apic_mode(apic) && offset == APIC_ICR)
-		kvm_x2apic_icr_write(apic, kvm_lapic_get_reg64(apic, APIC_ICR));
+		WARN_ON_ONCE(kvm_x2apic_icr_write(apic, kvm_x2apic_icr_read(apic)));
 	else
 		kvm_lapic_reg_write(apic, offset, kvm_lapic_get_reg(apic, offset));
 }
@@ -2594,19 +2629,26 @@ void kvm_apic_update_apicv(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
-	if (apic->apicv_active) {
-		/* irr_pending is always true when apicv is activated. */
-		apic->irr_pending = true;
+	/*
+	 * When APICv is enabled, KVM must always search the IRR for a pending
+	 * IRQ, as other vCPUs and devices can set IRR bits even if the vCPU
+	 * isn't running.  If APICv is disabled, KVM _should_ search the IRR
+	 * for a pending IRQ.  But KVM currently doesn't ensure *all* hardware,
+	 * e.g. CPUs and IOMMUs, has seen the change in state, i.e. searching
+	 * the IRR at this time could race with IRQ delivery from hardware that
+	 * still sees APICv as being enabled.
+	 *
+	 * FIXME: Ensure other vCPUs and devices observe the change in APICv
+	 *        state prior to updating KVM's metadata caches, so that KVM
+	 *        can safely search the IRR and set irr_pending accordingly.
+	 */
+	apic->irr_pending = true;
+
+	if (apic->apicv_active)
 		apic->isr_count = 1;
-	} else {
-		/*
-		 * Don't clear irr_pending, searching the IRR can race with
-		 * updates from the CPU as APICv is still active from hardware's
-		 * perspective.  The flag will be cleared as appropriate when
-		 * KVM injects the interrupt.
-		 */
+	else
 		apic->isr_count = count_vectors(apic->regs + APIC_ISR);
-	}
+
 	apic->highest_isr_cache = -1;
 }
 
@@ -2924,14 +2966,13 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu)
 	}
 }
 
-int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
+void kvm_apic_ack_interrupt(struct kvm_vcpu *vcpu, int vector)
 {
-	int vector = kvm_apic_has_interrupt(vcpu);
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	u32 ppr;
 
-	if (vector == -1)
-		return -1;
+	if (WARN_ON_ONCE(vector < 0 || !apic))
+		return;
 
 	/*
 	 * We get here even with APIC virtualization enabled, if doing
@@ -2959,41 +3000,55 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
 		__apic_update_ppr(apic, &ppr);
 	}
 
-	return vector;
 }
+EXPORT_SYMBOL_GPL(kvm_apic_ack_interrupt);
 
 static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
 		struct kvm_lapic_state *s, bool set)
 {
 	if (apic_x2apic_mode(vcpu->arch.apic)) {
+		u32 x2apic_id = kvm_x2apic_id(vcpu->arch.apic);
 		u32 *id = (u32 *)(s->regs + APIC_ID);
 		u32 *ldr = (u32 *)(s->regs + APIC_LDR);
 		u64 icr;
 
 		if (vcpu->kvm->arch.x2apic_format) {
-			if (*id != vcpu->vcpu_id)
+			if (*id != x2apic_id)
 				return -EINVAL;
 		} else {
+			/*
+			 * Ignore the userspace value when setting APIC state.
+			 * KVM's model is that the x2APIC ID is readonly, e.g.
+			 * KVM only supports delivering interrupts to KVM's
+			 * version of the x2APIC ID.  However, for backwards
+			 * compatibility, don't reject attempts to set a
+			 * mismatched ID for userspace that hasn't opted into
+			 * x2apic_format.
+			 */
 			if (set)
-				*id >>= 24;
+				*id = x2apic_id;
 			else
-				*id <<= 24;
+				*id = x2apic_id << 24;
 		}
 
 		/*
 		 * In x2APIC mode, the LDR is fixed and based on the id.  And
-		 * ICR is internally a single 64-bit register, but needs to be
-		 * split to ICR+ICR2 in userspace for backwards compatibility.
+		 * if the ICR is _not_ split, ICR is internally a single 64-bit
+		 * register, but needs to be split to ICR+ICR2 in userspace for
+		 * backwards compatibility.
 		 */
-		if (set) {
-			*ldr = kvm_apic_calc_x2apic_ldr(*id);
-
-			icr = __kvm_lapic_get_reg(s->regs, APIC_ICR) |
-			      (u64)__kvm_lapic_get_reg(s->regs, APIC_ICR2) << 32;
-			__kvm_lapic_set_reg64(s->regs, APIC_ICR, icr);
-		} else {
-			icr = __kvm_lapic_get_reg64(s->regs, APIC_ICR);
-			__kvm_lapic_set_reg(s->regs, APIC_ICR2, icr >> 32);
+		if (set)
+			*ldr = kvm_apic_calc_x2apic_ldr(x2apic_id);
+
+		if (!kvm_x86_ops.x2apic_icr_is_split) {
+			if (set) {
+				icr = __kvm_lapic_get_reg(s->regs, APIC_ICR) |
+				      (u64)__kvm_lapic_get_reg(s->regs, APIC_ICR2) << 32;
+				__kvm_lapic_set_reg64(s->regs, APIC_ICR, icr);
+			} else {
+				icr = __kvm_lapic_get_reg64(s->regs, APIC_ICR);
+				__kvm_lapic_set_reg(s->regs, APIC_ICR2, icr >> 32);
+			}
 		}
 	}
 
@@ -3186,22 +3241,12 @@ int kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr)
 	return 0;
 }
 
-int kvm_x2apic_icr_write(struct kvm_lapic *apic, u64 data)
-{
-	data &= ~APIC_ICR_BUSY;
-
-	kvm_apic_send_ipi(apic, (u32)data, (u32)(data >> 32));
-	kvm_lapic_set_reg64(apic, APIC_ICR, data);
-	trace_kvm_apic_write(APIC_ICR, data);
-	return 0;
-}
-
 static int kvm_lapic_msr_read(struct kvm_lapic *apic, u32 reg, u64 *data)
 {
 	u32 low;
 
 	if (reg == APIC_ICR) {
-		*data = kvm_lapic_get_reg64(apic, APIC_ICR);
+		*data = kvm_x2apic_icr_read(apic);
 		return 0;
 	}