hw/ide/ahci: Decouple from PCI

In some adhoc profiling booting Linux VMs, it's observed that ahci_irq_lower()
can be a hot path (10000+ triggers until login prompt appears). Even though the
parent device never changes, this method re-determines whether the parent device
is a PCI device or not using the rather expensive object_dynamic_cast()
function. Avoid this overhead by pushing the interrupt handling to the parent
device, essentially turning AHCIState into an "IP block".

Note that this change also frees AHCIState from the PCI dependency which wasn't
reflected in Kconfig.

Reported-by: Peter Xu <peterx@redhat.com>
Inspired-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241212110926.23548-2-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/ide/ahci-internal.h

@@ -25,7 +25,6 @@
 #define HW_IDE_AHCI_INTERNAL_H
 
 #include "hw/ide/ahci.h"
-#include "hw/pci/pci_device.h"
 #include "ide-internal.h"
 
 #define AHCI_MEM_BAR_SIZE         0x1000

hw/ide/ahci.c

@@ -23,8 +23,6 @@
 
 #include "qemu/osdep.h"
 #include "hw/irq.h"
-#include "hw/pci/msi.h"
-#include "hw/pci/pci.h"
 #include "hw/qdev-properties.h"
 #include "migration/vmstate.h"
 
@@ -34,8 +32,6 @@
 #include "qemu/module.h"
 #include "sysemu/block-backend.h"
 #include "sysemu/dma.h"
-#include "hw/ide/pci.h"
-#include "hw/ide/ahci-pci.h"
 #include "hw/ide/ahci-sysbus.h"
 #include "ahci-internal.h"
 #include "ide-internal.h"
@@ -179,34 +175,6 @@ static uint32_t ahci_port_read(AHCIState *s, int port, int offset)
     return val;
 }
 
-static void ahci_irq_raise(AHCIState *s)
-{
-    DeviceState *dev_state = s->container;
-    PCIDevice *pci_dev = (PCIDevice *) object_dynamic_cast(OBJECT(dev_state),
-                                                           TYPE_PCI_DEVICE);
-
-    trace_ahci_irq_raise(s);
-
-    if (pci_dev && msi_enabled(pci_dev)) {
-        msi_notify(pci_dev, 0);
-    } else {
-        qemu_irq_raise(s->irq);
-    }
-}
-
-static void ahci_irq_lower(AHCIState *s)
-{
-    DeviceState *dev_state = s->container;
-    PCIDevice *pci_dev = (PCIDevice *) object_dynamic_cast(OBJECT(dev_state),
-                                                           TYPE_PCI_DEVICE);
-
-    trace_ahci_irq_lower(s);
-
-    if (!pci_dev || !msi_enabled(pci_dev)) {
-        qemu_irq_lower(s->irq);
-    }
-}
-
 static void ahci_check_irq(AHCIState *s)
 {
     int i;
@@ -222,9 +190,11 @@ static void ahci_check_irq(AHCIState *s)
     trace_ahci_check_irq(s, old_irq, s->control_regs.irqstatus);
     if (s->control_regs.irqstatus &&
         (s->control_regs.ghc & HOST_CTL_IRQ_EN)) {
-            ahci_irq_raise(s);
+        trace_ahci_irq_raise(s);
+        qemu_irq_raise(s->irq);
     } else {
-        ahci_irq_lower(s);
+        trace_ahci_irq_lower(s);
+        qemu_irq_lower(s->irq);
     }
 }
 
@@ -1608,7 +1578,6 @@ static const IDEDMAOps ahci_dma_ops = {
 
 void ahci_init(AHCIState *s, DeviceState *qdev)
 {
-    s->container = qdev;
     /* XXX BAR size should be 1k, but that breaks, so bump it to 4k for now */
     memory_region_init_io(&s->mem, OBJECT(qdev), &ahci_mem_ops, s,
                           "ahci", AHCI_MEM_BAR_SIZE);

hw/ide/ich.c

@@ -61,7 +61,6 @@
  */
 
 #include "qemu/osdep.h"
-#include "hw/irq.h"
 #include "hw/pci/msi.h"
 #include "hw/pci/pci.h"
 #include "migration/vmstate.h"
@@ -91,6 +90,19 @@ static const VMStateDescription vmstate_ich9_ahci = {
     },
 };
 
+static void pci_ich9_ahci_update_irq(void *opaque, int irq_num, int level)
+{
+    PCIDevice *pci_dev = opaque;
+
+    if (msi_enabled(pci_dev)) {
+        if (level) {
+            msi_notify(pci_dev, 0);
+        }
+    } else {
+        pci_set_irq(pci_dev, level);
+    }
+}
+
 static void pci_ich9_reset(DeviceState *dev)
 {
     AHCIPCIState *d = ICH9_AHCI(dev);
@@ -102,7 +114,9 @@ static void pci_ich9_ahci_init(Object *obj)
 {
     AHCIPCIState *d = ICH9_AHCI(obj);
 
+    qemu_init_irq(&d->irq, pci_ich9_ahci_update_irq, d, 0);
     ahci_init(&d->ahci, DEVICE(obj));
+    d->ahci.irq = &d->irq;
 }
 
 static void pci_ich9_ahci_realize(PCIDevice *dev, Error **errp)
@@ -125,8 +139,6 @@ static void pci_ich9_ahci_realize(PCIDevice *dev, Error **errp)
     /* XXX Software should program this register */
     dev->config[0x90]   = 1 << 6; /* Address Map Register - AHCI mode */
 
-    d->ahci.irq = pci_allocate_irq(dev);
-
     pci_register_bar(dev, ICH9_IDP_BAR, PCI_BASE_ADDRESS_SPACE_IO,
                      &d->ahci.idp);
     pci_register_bar(dev, ICH9_MEM_BAR, PCI_BASE_ADDRESS_SPACE_MEMORY,
@@ -161,7 +173,6 @@ static void pci_ich9_uninit(PCIDevice *dev)
 
     msi_uninit(dev);
     ahci_uninit(&d->ahci);
-    qemu_free_irq(d->ahci.irq);
 }
 
 static void ich_ahci_class_init(ObjectClass *klass, void *data)

include/hw/ide/ahci-pci.h

@@ -9,6 +9,7 @@
 #include "qom/object.h"
 #include "hw/ide/ahci.h"
 #include "hw/pci/pci_device.h"
+#include "hw/irq.h"
 
 #define TYPE_ICH9_AHCI "ich9-ahci"
 OBJECT_DECLARE_SIMPLE_TYPE(AHCIPCIState, ICH9_AHCI)
@@ -17,6 +18,7 @@ struct AHCIPCIState {
     PCIDevice parent_obj;
 
     AHCIState ahci;
+    IRQState irq;
 };
 
 #endif

include/hw/ide/ahci.h

@@ -37,8 +37,6 @@ typedef struct AHCIControlRegs {
 } AHCIControlRegs;
 
 typedef struct AHCIState {
-    DeviceState *container;
-
     AHCIDevice *dev;
     AHCIControlRegs control_regs;
     MemoryRegion mem;