Merge branch 'topic/ppc-kvm' into next

Merge our ppc-kvm topic branch. This contains several fixes for the XIVE
interrupt controller that we are sharing with the KVM tree.

Author: mpe

arch/powerpc/include/asm/xive.h

@@ -46,7 +46,15 @@ struct xive_irq_data {
 
 	/* Setup/used by frontend */
 	int target;
+	/*
+	 * saved_p means that there is a queue entry for this interrupt
+	 * in some CPU's queue (not including guest vcpu queues), even
+	 * if P is not set in the source ESB.
+	 * stale_p means that there is no queue entry for this interrupt
+	 * in some CPU's queue, even if P is set in the source ESB.
+	 */
 	bool saved_p;
+	bool stale_p;
 };
 #define XIVE_IRQ_FLAG_STORE_EOI	0x01
 #define XIVE_IRQ_FLAG_LSI	0x02

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -942,6 +942,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
 	ld	r11, VCPU_XIVE_SAVED_STATE(r4)
 	li	r9, TM_QW1_OS
 	lwz	r8, VCPU_XIVE_CAM_WORD(r4)
+	cmpwi	r8, 0
+	beq	no_xive
 	li	r7, TM_QW1_OS + TM_WORD2
 	mfmsr	r0
 	andi.	r0, r0, MSR_DR		/* in real mode? */
@@ -2831,29 +2833,39 @@ kvm_cede_prodded:
 kvm_cede_exit:
 	ld	r9, HSTATE_KVM_VCPU(r13)
 #ifdef CONFIG_KVM_XICS
-	/* Abort if we still have a pending escalation */
+	/* are we using XIVE with single escalation? */
+	ld	r10, VCPU_XIVE_ESC_VADDR(r9)
+	cmpdi	r10, 0
+	beq	3f
+	li	r6, XIVE_ESB_SET_PQ_00
+	/*
+	 * If we still have a pending escalation, abort the cede,
+	 * and we must set PQ to 10 rather than 00 so that we don't
+	 * potentially end up with two entries for the escalation
+	 * interrupt in the XIVE interrupt queue.  In that case
+	 * we also don't want to set xive_esc_on to 1 here in
+	 * case we race with xive_esc_irq().
+	 */
 	lbz	r5, VCPU_XIVE_ESC_ON(r9)
 	cmpwi	r5, 0
-	beq	1f
+	beq	4f
 	li	r0, 0
 	stb	r0, VCPU_CEDED(r9)
-1:	/* Enable XIVE escalation */
-	li	r5, XIVE_ESB_SET_PQ_00
+	li	r6, XIVE_ESB_SET_PQ_10
+	b	5f
+4:	li	r0, 1
+	stb	r0, VCPU_XIVE_ESC_ON(r9)
+	/* make sure store to xive_esc_on is seen before xive_esc_irq runs */
+	sync
+5:	/* Enable XIVE escalation */
 	mfmsr	r0
 	andi.	r0, r0, MSR_DR		/* in real mode? */
 	beq	1f
-	ld	r10, VCPU_XIVE_ESC_VADDR(r9)
-	cmpdi	r10, 0
-	beq	3f
-	ldx	r0, r10, r5
+	ldx	r0, r10, r6
 	b	2f
 1:	ld	r10, VCPU_XIVE_ESC_RADDR(r9)
-	cmpdi	r10, 0
-	beq	3f
-	ldcix	r0, r10, r5
+	ldcix	r0, r10, r6
 2:	sync
-	li	r0, 1
-	stb	r0, VCPU_XIVE_ESC_ON(r9)
 #endif /* CONFIG_KVM_XICS */
 3:	b	guest_exit_cont
 

arch/powerpc/kvm/book3s_xive.c

@@ -67,8 +67,14 @@ void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu)
 	void __iomem *tima = local_paca->kvm_hstate.xive_tima_virt;
 	u64 pq;
 
-	if (!tima)
+	/*
+	 * Nothing to do if the platform doesn't have a XIVE
+	 * or this vCPU doesn't have its own XIVE context
+	 * (e.g. because it's not using an in-kernel interrupt controller).
+	 */
+	if (!tima || !vcpu->arch.xive_cam_word)
 		return;
+
 	eieio();
 	__raw_writeq(vcpu->arch.xive_saved_state.w01, tima + TM_QW1_OS);
 	__raw_writel(vcpu->arch.xive_cam_word, tima + TM_QW1_OS + TM_WORD2);
@@ -160,6 +166,9 @@ static irqreturn_t xive_esc_irq(int irq, void *data)
 	 */
 	vcpu->arch.xive_esc_on = false;
 
+	/* This orders xive_esc_on = false vs. subsequent stale_p = true */
+	smp_wmb();	/* goes with smp_mb() in cleanup_single_escalation */
+
 	return IRQ_HANDLED;
 }
 
@@ -1113,6 +1122,31 @@ void kvmppc_xive_disable_vcpu_interrupts(struct kvm_vcpu *vcpu)
 	vcpu->arch.xive_esc_raddr = 0;
 }
 
+/*
+ * In single escalation mode, the escalation interrupt is marked so
+ * that EOI doesn't re-enable it, but just sets the stale_p flag to
+ * indicate that the P bit has already been dealt with.  However, the
+ * assembly code that enters the guest sets PQ to 00 without clearing
+ * stale_p (because it has no easy way to address it).  Hence we have
+ * to adjust stale_p before shutting down the interrupt.
+ */
+void xive_cleanup_single_escalation(struct kvm_vcpu *vcpu,
+				    struct kvmppc_xive_vcpu *xc, int irq)
+{
+	struct irq_data *d = irq_get_irq_data(irq);
+	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
+
+	/*
+	 * This slightly odd sequence gives the right result
+	 * (i.e. stale_p set if xive_esc_on is false) even if
+	 * we race with xive_esc_irq() and xive_irq_eoi().
+	 */
+	xd->stale_p = false;
+	smp_mb();		/* paired with smb_wmb in xive_esc_irq */
+	if (!vcpu->arch.xive_esc_on)
+		xd->stale_p = true;
+}
+
 void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
@@ -1134,20 +1168,28 @@ void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 	/* Mask the VP IPI */
 	xive_vm_esb_load(&xc->vp_ipi_data, XIVE_ESB_SET_PQ_01);
 
-	/* Disable the VP */
-	xive_native_disable_vp(xc->vp_id);
-
-	/* Free the queues & associated interrupts */
+	/* Free escalations */
 	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
-		struct xive_q *q = &xc->queues[i];
-
-		/* Free the escalation irq */
 		if (xc->esc_virq[i]) {
+			if (xc->xive->single_escalation)
+				xive_cleanup_single_escalation(vcpu, xc,
+							xc->esc_virq[i]);
 			free_irq(xc->esc_virq[i], vcpu);
 			irq_dispose_mapping(xc->esc_virq[i]);
 			kfree(xc->esc_virq_names[i]);
 		}
-		/* Free the queue */
+	}
+
+	/* Disable the VP */
+	xive_native_disable_vp(xc->vp_id);
+
+	/* Clear the cam word so guest entry won't try to push context */
+	vcpu->arch.xive_cam_word = 0;
+
+	/* Free the queues */
+	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
+		struct xive_q *q = &xc->queues[i];
+
 		xive_native_disable_queue(xc->vp_id, q, i);
 		if (q->qpage) {
 			free_pages((unsigned long)q->qpage,

arch/powerpc/kvm/book3s_xive.h

@@ -282,6 +282,8 @@ int kvmppc_xive_select_target(struct kvm *kvm, u32 *server, u8 prio);
 int kvmppc_xive_attach_escalation(struct kvm_vcpu *vcpu, u8 prio,
 				  bool single_escalation);
 struct kvmppc_xive *kvmppc_xive_get_device(struct kvm *kvm, u32 type);
+void xive_cleanup_single_escalation(struct kvm_vcpu *vcpu,
+				    struct kvmppc_xive_vcpu *xc, int irq);
 
 #endif /* CONFIG_KVM_XICS */
 #endif /* _KVM_PPC_BOOK3S_XICS_H */

arch/powerpc/kvm/book3s_xive_native.c

@@ -67,20 +67,28 @@ void kvmppc_xive_native_cleanup_vcpu(struct kvm_vcpu *vcpu)
 	xc->valid = false;
 	kvmppc_xive_disable_vcpu_interrupts(vcpu);
 
-	/* Disable the VP */
-	xive_native_disable_vp(xc->vp_id);
-
-	/* Free the queues & associated interrupts */
+	/* Free escalations */
 	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
 		/* Free the escalation irq */
 		if (xc->esc_virq[i]) {
+			if (xc->xive->single_escalation)
+				xive_cleanup_single_escalation(vcpu, xc,
+							xc->esc_virq[i]);
 			free_irq(xc->esc_virq[i], vcpu);
 			irq_dispose_mapping(xc->esc_virq[i]);
 			kfree(xc->esc_virq_names[i]);
 			xc->esc_virq[i] = 0;
 		}
+	}
 
-		/* Free the queue */
+	/* Disable the VP */
+	xive_native_disable_vp(xc->vp_id);
+
+	/* Clear the cam word so guest entry won't try to push context */
+	vcpu->arch.xive_cam_word = 0;
+
+	/* Free the queues */
+	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
 		kvmppc_xive_native_cleanup_queue(vcpu, i);
 	}