[PATCH v4 07/12] x86/dpci: switch to use a GSI EOI callback

[Roger Pau Monne <roger.pau@citrix.com>]

Switch the dpci GSI EOI callback hooks to use the newly introduced
generic callback functionality, and remove the custom dpci calls found
on the vPIC and vIO-APIC implementations.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v3:
 - Print a warning message if the EOI callback cannot be unregistered.

Changes since v2:
 - Avoid leaking the allocated callback on error paths of
   pt_irq_create_bind.

Changes since v1:
 - New in this version.
---
 xen/arch/x86/hvm/vioapic.c        |  8 -----
 xen/arch/x86/hvm/vpic.c           |  4 ---
 xen/drivers/passthrough/x86/hvm.c | 57 ++++++++++++++++++++++++++++---
 xen/include/asm-x86/hvm/io.h      |  1 -
 xen/include/asm-x86/hvm/irq.h     |  1 +
 5 files changed, 54 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index 0824ede91ab..4f844965423 100644
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -284,7 +284,6 @@ static void vioapic_write_redirent(
              */
             ASSERT(prev_level);
             ASSERT(!top_word);
-            hvm_dpci_eoi(d, gsi);
             hvm_gsi_execute_callbacks(d, gsi);
     }
 
@@ -418,13 +417,6 @@ static void eoi_callback(struct vcpu *v, unsigned int vector, void *data)
 
             ent->fields.remote_irr = 0;
 
-            if ( is_iommu_enabled(d) )
-            {
-                spin_unlock(&d->arch.hvm.irq_lock);
-                hvm_dpci_eoi(d, gsi);
-                spin_lock(&d->arch.hvm.irq_lock);
-            }
-
             /*
              * Callbacks don't expect to be executed with any lock held, so
              * drop the lock that protects the vIO-APIC fields from changing.
diff --git a/xen/arch/x86/hvm/vpic.c b/xen/arch/x86/hvm/vpic.c
index ef668f3668a..60d6740f69a 100644
--- a/xen/arch/x86/hvm/vpic.c
+++ b/xen/arch/x86/hvm/vpic.c
@@ -237,8 +237,6 @@ static void vpic_ioport_write(
                 ASSERT(pin < 8);
                 hvm_gsi_execute_callbacks(current->domain,
                         hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin));
-                hvm_dpci_eoi(current->domain,
-                             hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin));
                 __clear_bit(pin, &pending);
             }
             return;
@@ -289,8 +287,6 @@ static void vpic_ioport_write(
                 vpic_unlock(vpic);
                 hvm_gsi_execute_callbacks(current->domain,
                         hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin));
-                hvm_dpci_eoi(current->domain,
-                             hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin));
                 return; /* bail immediately */
             case 6: /* Set Priority                */
                 vpic->priority_add = (val + 1) & 7;
diff --git a/xen/drivers/passthrough/x86/hvm.c b/xen/drivers/passthrough/x86/hvm.c
index 0db26e5dbb2..02e027cff8c 100644
--- a/xen/drivers/passthrough/x86/hvm.c
+++ b/xen/drivers/passthrough/x86/hvm.c
@@ -252,7 +252,7 @@ static void hvm_gsi_eoi(struct domain *d, unsigned int gsi)
     hvm_pirq_eoi(pirq);
 }
 
-void hvm_dpci_eoi(struct domain *d, unsigned int guest_gsi)
+static void dpci_eoi(struct domain *d, unsigned int guest_gsi, void *data)
 {
     const struct hvm_irq_dpci *hvm_irq_dpci;
     const struct hvm_girq_dpci_mapping *girq;
@@ -476,6 +476,7 @@ int pt_irq_create_bind(
     {
         struct dev_intx_gsi_link *digl = NULL;
         struct hvm_girq_dpci_mapping *girq = NULL;
+        struct hvm_gsi_eoi_callback *cb = NULL;
         unsigned int guest_gsi;
 
         /*
@@ -489,7 +490,7 @@ int pt_irq_create_bind(
             unsigned int link;
 
             digl = xmalloc(struct dev_intx_gsi_link);
-            girq = xmalloc(struct hvm_girq_dpci_mapping);
+            girq = xzalloc(struct hvm_girq_dpci_mapping);
 
             if ( !digl || !girq )
             {
@@ -502,11 +503,22 @@ int pt_irq_create_bind(
             girq->bus = digl->bus = pt_irq_bind->u.pci.bus;
             girq->device = digl->device = pt_irq_bind->u.pci.device;
             girq->intx = digl->intx = pt_irq_bind->u.pci.intx;
-            list_add_tail(&digl->list, &pirq_dpci->digl_list);
+            girq->cb.callback = dpci_eoi;
 
             guest_gsi = hvm_pci_intx_gsi(digl->device, digl->intx);
             link = hvm_pci_intx_link(digl->device, digl->intx);
 
+            rc = hvm_gsi_register_callback(d, guest_gsi, &girq->cb);
+            if ( rc )
+            {
+                spin_unlock(&d->event_lock);
+                xfree(girq);
+                xfree(digl);
+                return rc;
+            }
+
+            list_add_tail(&digl->list, &pirq_dpci->digl_list);
+
             hvm_irq_dpci->link_cnt[link]++;
 
             girq->machine_gsi = pirq;
@@ -514,17 +526,43 @@ int pt_irq_create_bind(
         }
         else
         {
+            /*
+             * NB: the callback structure allocated below will never be freed
+             * once setup because it's used by the hardware domain and will
+             * never be unregistered.
+             */
+            cb = xzalloc(struct hvm_gsi_eoi_callback);
+
             ASSERT(is_hardware_domain(d));
 
+            if ( !cb )
+            {
+                spin_unlock(&d->event_lock);
+                return -ENOMEM;
+            }
+
             /* MSI_TRANSLATE is not supported for the hardware domain. */
             if ( pt_irq_bind->irq_type != PT_IRQ_TYPE_PCI ||
                  pirq >= hvm_domain_irq(d)->nr_gsis )
             {
                 spin_unlock(&d->event_lock);
-
+                xfree(cb);
                 return -EINVAL;
             }
             guest_gsi = pirq;
+
+            cb->callback = dpci_eoi;
+            /*
+             * IRQ binds created for the hardware domain are never destroyed,
+             * so it's fine to not keep a reference to cb here.
+             */
+            rc = hvm_gsi_register_callback(d, guest_gsi, cb);
+            if ( rc )
+            {
+                spin_unlock(&d->event_lock);
+                xfree(cb);
+                return rc;
+            }
         }
 
         /* Bind the same mirq once in the same domain */
@@ -596,12 +634,17 @@ int pt_irq_create_bind(
                     list_del(&digl->list);
                     link = hvm_pci_intx_link(digl->device, digl->intx);
                     hvm_irq_dpci->link_cnt[link]--;
+                    hvm_gsi_unregister_callback(d, guest_gsi, &girq->cb);
                 }
+                else
+                    hvm_gsi_unregister_callback(d, guest_gsi, cb);
+
                 pirq_dpci->flags = 0;
                 pirq_cleanup_check(info, d);
                 spin_unlock(&d->event_lock);
                 xfree(girq);
                 xfree(digl);
+                xfree(cb);
                 return rc;
             }
         }
@@ -699,6 +742,7 @@ int pt_irq_destroy_bind(
         unsigned int link = hvm_pci_intx_link(device, intx);
         struct hvm_girq_dpci_mapping *girq;
         struct dev_intx_gsi_link *digl, *tmp;
+        int rc;
 
         list_for_each_entry ( girq, &hvm_irq_dpci->girq[guest_gsi], list )
         {
@@ -708,6 +752,11 @@ int pt_irq_destroy_bind(
                  girq->machine_gsi == machine_gsi )
             {
                 list_del(&girq->list);
+                rc = hvm_gsi_unregister_callback(d, guest_gsi, &girq->cb);
+                if ( rc )
+                    printk(XENLOG_G_WARNING
+                           "%pd: unable to remove callback for GSI %u: %d\n",
+                           d, guest_gsi, rc);
                 xfree(girq);
                 girq = NULL;
                 break;
diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index 7f30dfa7fea..977a857f729 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -101,7 +101,6 @@ bool handle_mmio_with_translation(unsigned long gla, unsigned long gpfn,
                                   struct npfec);
 bool handle_pio(uint16_t port, unsigned int size, int dir);
 void hvm_interrupt_post(struct vcpu *v, int vector, int type);
-void hvm_dpci_eoi(struct domain *d, unsigned int guest_irq);
 void msix_write_completion(struct vcpu *);
 
 #ifdef CONFIG_HVM
diff --git a/xen/include/asm-x86/hvm/irq.h b/xen/include/asm-x86/hvm/irq.h
index 37b8d2ba8fb..57d51c15863 100644
--- a/xen/include/asm-x86/hvm/irq.h
+++ b/xen/include/asm-x86/hvm/irq.h
@@ -156,6 +156,7 @@ struct hvm_girq_dpci_mapping {
     uint8_t device;
     uint8_t intx;
     uint8_t machine_gsi;
+    struct hvm_gsi_eoi_callback cb;
 };
 
 #define NR_ISAIRQS  16
-- 
2.30.1