[Qemu-devel] [PATCH v2 3/4] pcihp: make pci_read() mmio calback compatible with legacy ACPI hotplug

[Igor Mammedov <imammedo@redhat.com>]

due to recent change introduced by:
"pcihp: reduce number of device check events"

'up' field is cleared right after it's read.
This is incompatible with legacy BIOS ACPI code
where PCNF ACPI method reads this field 32 times.

To make pci_read mmio callback compatible with legacy
'up' behavior, pcihp code will need to know in which
mode it runs so move 'use_acpi_pci_hotplug' into
AcpiPciHpState structure and alter register behavior
accordingly.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/acpi/pcihp.c         |    4 +++-
 hw/acpi/piix4.c         |   13 ++++++-------
 include/hw/acpi/pcihp.h |    1 +
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index 64c8cf2..e48b758 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -215,7 +215,9 @@ static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
     switch (addr) {
     case PCI_UP_BASE:
         val = s->acpi_pcihp_pci_status[bsel].up;
-        s->acpi_pcihp_pci_status[bsel].up = 0;
+        if (s->use_acpi_pci_hotplug) {
+            s->acpi_pcihp_pci_status[bsel].up = 0;
+        }
         ACPI_PCIHP_DPRINTF("pci_up_read %" PRIu32 "\n", val);
         break;
     case PCI_DOWN_BASE:
diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 5d55a3c..a20453d 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -88,7 +88,6 @@ typedef struct PIIX4PMState {
 
     /* for new pci hotplug (with PCI2PCI bridge support) */
     AcpiPciHpState acpi_pci_hotplug;
-    bool use_acpi_pci_hotplug;
 
     uint8_t disable_s3;
     uint8_t disable_s4;
@@ -263,13 +262,13 @@ static int acpi_load_old(QEMUFile *f, void *opaque, int version_id)
 static bool vmstate_test_use_acpi_pci_hotplug(void *opaque, int version_id)
 {
     PIIX4PMState *s = opaque;
-    return s->use_acpi_pci_hotplug;
+    return s->acpi_pci_hotplug.use_acpi_pci_hotplug;
 }
 
 static bool vmstate_test_no_use_acpi_pci_hotplug(void *opaque, int version_id)
 {
     PIIX4PMState *s = opaque;
-    return !s->use_acpi_pci_hotplug;
+    return !s->acpi_pci_hotplug.use_acpi_pci_hotplug;
 }
 
 /* qemu-kvm 1.2 uses version 3 but advertised as 2
@@ -377,7 +376,7 @@ static void piix4_reset(void *opaque)
         pci_conf[0x5B] = 0x02;
     }
     pm_io_space_update(s);
-    if (s->use_acpi_pci_hotplug) {
+    if (s->acpi_pci_hotplug.use_acpi_pci_hotplug) {
         acpi_pcihp_reset(&s->acpi_pci_hotplug);
     } else {
         piix4_update_hotplug(s);
@@ -426,7 +425,7 @@ static void piix4_pm_machine_ready(Notifier *n, void *opaque)
     pci_conf[0x67] = (memory_region_present(io_as, 0x3f8) ? 0x08 : 0) |
         (memory_region_present(io_as, 0x2f8) ? 0x90 : 0);
 
-    if (s->use_acpi_pci_hotplug) {
+    if (s->acpi_pci_hotplug.use_acpi_pci_hotplug) {
         pci_for_each_bus(d->bus, piix4_update_bus_hotplug, s);
     }
 }
@@ -551,7 +550,7 @@ static Property piix4_pm_properties[] = {
     DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_DISABLED, PIIX4PMState, disable_s4, 0),
     DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2),
     DEFINE_PROP_BOOL("acpi-pci-hotplug-with-bridge-support", PIIX4PMState,
-                     use_acpi_pci_hotplug, true),
+                     acpi_pci_hotplug.use_acpi_pci_hotplug, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -694,7 +693,7 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
                           "acpi-gpe0", GPE_LEN);
     memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
 
-    if (s->use_acpi_pci_hotplug) {
+    if (s->acpi_pci_hotplug.use_acpi_pci_hotplug) {
         acpi_pcihp_init(&s->acpi_pci_hotplug, bus, parent);
     } else {
         memory_region_init_io(&s->io_pci, OBJECT(s), &piix4_pci_ops, s,
diff --git a/include/hw/acpi/pcihp.h b/include/hw/acpi/pcihp.h
index aa297c2..cff5270 100644
--- a/include/hw/acpi/pcihp.h
+++ b/include/hw/acpi/pcihp.h
@@ -46,6 +46,7 @@ typedef struct AcpiPciHpState {
     uint32_t hotplug_select;
     PCIBus *root;
     MemoryRegion io;
+    bool use_acpi_pci_hotplug;
 } AcpiPciHpState;
 
 void acpi_pcihp_init(AcpiPciHpState *, PCIBus *root,
-- 
1.7.1