[v2,08/11] x86/dpci: switch to use a GSI EOI callback

Commit Message

Roger Pau Monné Sept. 30, 2020, 10:41 a.m. UTC

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 <[e-mail]>
---
Changes since v1:
 - New in this version.
---
 xen/arch/x86/hvm/vioapic.c    |  7 ------
 xen/arch/x86/hvm/vpic.c       |  2 --
 xen/drivers/passthrough/io.c  | 41 ++++++++++++++++++++++++++++++++---
 xen/include/asm-x86/hvm/io.h  |  1 -
 xen/include/asm-x86/hvm/irq.h |  1 +
 5 files changed, 39 insertions(+), 13 deletions(-)

Comments

Jan Beulich Oct. 23, 2020, 12:47 p.m. UTC | #1

On 30.09.2020 12:41, Roger Pau Monne wrote:
> --- a/xen/drivers/passthrough/io.c
> +++ b/xen/drivers/passthrough/io.c
> @@ -327,9 +327,10 @@ static void hvm_gsi_eoi(struct domain *d, unsigned int gsi,
>      hvm_pirq_eoi(pirq, ent);
>  }
>  
> -void hvm_dpci_eoi(unsigned int guest_gsi, const union vioapic_redir_entry *ent)
> +static void dpci_eoi(unsigned int guest_gsi, void *data)
>  {
>      struct domain *d = current->domain;
> +    const union vioapic_redir_entry *ent = data;
>      const struct hvm_irq_dpci *hvm_irq_dpci;
>      const struct hvm_girq_dpci_mapping *girq;
>  
> @@ -565,7 +566,7 @@ 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 )
>              {
> @@ -578,11 +579,22 @@ 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);

So this is where my question on the earlier patch gets answered:
You utilize passing NULL data to the callback to actually get
passed the IO-APIC redir entry pointer into the callback. This is
perhaps okay in principle if it was half way visible. May I ask
that at the very least instead of switching to xzalloc above you
set ->data to NULL here explicitly, accompanied by a comment on
the effect?

However, I wonder whether it wouldn't be better to have the
callback be passed const union vioapic_redir_entry * right away.
Albeit I haven't looked at the later patches yes, where it may
well be I'd find arguments against.

> @@ -590,8 +602,17 @@ int pt_irq_create_bind(
>          }
>          else
>          {
> +            struct hvm_gsi_eoi_callback *cb =
> +                xzalloc(struct hvm_gsi_eoi_callback);

I can't seem to be able to spot anywhere that this would get freed
(except on an error path in this function).

>              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 )
> @@ -601,6 +622,19 @@ int pt_irq_create_bind(
>                  return -EINVAL;
>              }

There's an error path here where you don't free cb, and I think
one or two more further down (where you then also may need to
unregister it first).

Jan

Patch

diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index 03b1350c04..ea4d60d33e 100644
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -400,13 +400,6 @@  static void eoi_callback(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(gsi, ent);
-                spin_lock(&d->arch.hvm.irq_lock);
-            }
-
             spin_unlock(&d->arch.hvm.irq_lock);
             hvm_gsi_execute_callbacks(gsi, ent);
             spin_lock(&d->arch.hvm.irq_lock);
diff --git a/xen/arch/x86/hvm/vpic.c b/xen/arch/x86/hvm/vpic.c
index 09c937c322..3c01c638fa 100644
--- a/xen/arch/x86/hvm/vpic.c
+++ b/xen/arch/x86/hvm/vpic.c
@@ -266,8 +266,6 @@  static void vpic_ioport_write(
                 hvm_gsi_execute_callbacks(
                         hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin),
                         NULL);
-                hvm_dpci_eoi(hvm_isa_irq_to_gsi((addr >> 7) ? (pin | 8) : pin),
-                             NULL);
                 return; /* bail immediately */
 
             case 6: /* Set Priority                */
diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 770a5cce6b..6908438a94 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -327,9 +327,10 @@  static void hvm_gsi_eoi(struct domain *d, unsigned int gsi,
     hvm_pirq_eoi(pirq, ent);
 }
 
-void hvm_dpci_eoi(unsigned int guest_gsi, const union vioapic_redir_entry *ent)
+static void dpci_eoi(unsigned int guest_gsi, void *data)
 {
     struct domain *d = current->domain;
+    const union vioapic_redir_entry *ent = data;
     const struct hvm_irq_dpci *hvm_irq_dpci;
     const struct hvm_girq_dpci_mapping *girq;
 
@@ -565,7 +566,7 @@  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 )
             {
@@ -578,11 +579,22 @@  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;
@@ -590,8 +602,17 @@  int pt_irq_create_bind(
         }
         else
         {
+            struct hvm_gsi_eoi_callback *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 )
@@ -601,6 +622,19 @@  int pt_irq_create_bind(
                 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 */
@@ -789,6 +823,7 @@  int pt_irq_destroy_bind(
                  girq->machine_gsi == machine_gsi )
             {
                 list_del(&girq->list);
+                hvm_gsi_unregister_callback(d, guest_gsi, &girq->cb);
                 xfree(girq);
                 girq = NULL;
                 break;
diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index 759ee486af..e1bc556613 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -118,7 +118,6 @@  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(unsigned int guest_irq, const union vioapic_redir_entry *ent);
 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 db38c3e119..2f01d8fe64 100644
--- a/xen/include/asm-x86/hvm/irq.h
+++ b/xen/include/asm-x86/hvm/irq.h
@@ -158,6 +158,7 @@  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