[RFC PATCH 5/9] acpi_piix4: Implement memory device hotplug registers

[Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>]

 A 32-byte register is used to present up to 256 hotplug-able memory devices
 to BIOS and OSPM. Hot-add and hot-remove functions trigger an ACPI hotplug
 event through these. Only reads are allowed from these registers (from
 BIOS/OSPM perspective). "memslot id add" will immediately populate the new
 memslot (a new MemoryRegion is created and attached to system memory), and
 then trigger the ACPI hot-add event. "memslot id delete" triggers the ACPI
 hot-remove event but needs to wait for OSPM to eject the device.  We use a
 second set of eject registers to know when OSPM has called the _EJ function
 for a particular memslot. A write to these will depopulate the corresponding
 memslot i.e. detach and free the MemoryRegion. Only writes to the eject
 registers are allowed.

 A new property mem_acpi_hotplug should enable these memory hotplug registers
 for future machine types (not yet implemented in this version).

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
---
 hw/acpi_piix4.c |   93 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 89 insertions(+), 4 deletions(-)

diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
index 797ed24..a14dd3c 100644
--- a/hw/acpi_piix4.c
+++ b/hw/acpi_piix4.c
@@ -27,6 +27,8 @@
 #include "sysemu.h"
 #include "range.h"
 #include "ioport.h"
+#include "sysbus.h"
+#include "memslot.h"
 
 //#define DEBUG
 
@@ -43,9 +45,16 @@
 #define PCI_BASE 0xae00
 #define PCI_EJ_BASE 0xae08
 #define PCI_RMV_BASE 0xae0c
+#define MEM_BASE 0xaf20
+#define MEM_EJ_BASE 0xaf40
 
+#define PIIX4_MEM_HOTPLUG_STATUS 8
 #define PIIX4_PCI_HOTPLUG_STATUS 2
 
+struct gpe_regs {
+    uint8_t mems_sts[32];
+};
+
 struct pci_status {
     uint32_t up;
     uint32_t down;
@@ -66,6 +75,7 @@ typedef struct PIIX4PMState {
     int kvm_enabled;
     Notifier machine_ready;
 
+    struct gpe_regs    gpe;
     /* for pci hotplug */
     struct pci_status pci0_status;
     uint32_t pci0_hotplug_enable;
@@ -86,8 +96,8 @@ static void pm_update_sci(PIIX4PMState *s)
                    ACPI_BITMASK_POWER_BUTTON_ENABLE |
                    ACPI_BITMASK_GLOBAL_LOCK_ENABLE |
                    ACPI_BITMASK_TIMER_ENABLE)) != 0) ||
-        (((s->ar.gpe.sts[0] & s->ar.gpe.en[0])
-          & PIIX4_PCI_HOTPLUG_STATUS) != 0);
+        (((s->ar.gpe.sts[0] & s->ar.gpe.en[0]) &
+          (PIIX4_PCI_HOTPLUG_STATUS | PIIX4_MEM_HOTPLUG_STATUS)) != 0);
 
     qemu_set_irq(s->irq, sci_level);
     /* schedule a timer interruption if needed */
@@ -432,17 +442,34 @@ type_init(piix4_pm_register_types)
 static uint32_t gpe_readb(void *opaque, uint32_t addr)
 {
     PIIX4PMState *s = opaque;
-    uint32_t val = acpi_gpe_ioport_readb(&s->ar, addr);
+    uint32_t val = 0;
+    struct gpe_regs *g = &s->gpe;
+
+    switch (addr) {
+        case MEM_BASE ... MEM_BASE+31:
+            val = g->mems_sts[addr - MEM_BASE];
+            break;
+        default:
+            val = acpi_gpe_ioport_readb(&s->ar, addr);
+    }
 
     PIIX4_DPRINTF("gpe read %x == %x\n", addr, val);
     return val;
 }
 
+static void piix4_memslot_eject(uint32_t addr, uint32_t val);
+
 static void gpe_writeb(void *opaque, uint32_t addr, uint32_t val)
 {
     PIIX4PMState *s = opaque;
 
-    acpi_gpe_ioport_writeb(&s->ar, addr, val);
+    switch (addr) {
+        case MEM_EJ_BASE ... MEM_EJ_BASE+31:
+            piix4_memslot_eject(addr, val);
+            break;
+        default:
+            acpi_gpe_ioport_writeb(&s->ar, addr, val);
+    }
     pm_update_sci(s);
 
     PIIX4_DPRINTF("gpe write %x <== %d\n", addr, val);
@@ -521,9 +548,12 @@ static void pcirmv_write(void *opaque, uint32_t addr, uint32_t val)
 static int piix4_device_hotplug(DeviceState *qdev, PCIDevice *dev,
                                 PCIHotplugState state);
 
+static int piix4_memslot_hotplug(DeviceState *qdev, SysBusDevice *dev, int add);
+
 static void piix4_acpi_system_hot_add_init(PCIBus *bus, PIIX4PMState *s)
 {
     struct pci_status *pci0_status = &s->pci0_status;
+    int i = 0;
 
     register_ioport_write(GPE_BASE, GPE_LEN, 1, gpe_writeb, s);
     register_ioport_read(GPE_BASE, GPE_LEN, 1,  gpe_readb, s);
@@ -538,6 +568,13 @@ static void piix4_acpi_system_hot_add_init(PCIBus *bus, PIIX4PMState *s)
     register_ioport_write(PCI_RMV_BASE, 4, 4, pcirmv_write, s);
     register_ioport_read(PCI_RMV_BASE, 4, 4,  pcirmv_read, s);
 
+    register_ioport_read(MEM_BASE, 32, 1,  gpe_readb, s);
+    register_ioport_write(MEM_EJ_BASE, 32, 1,  gpe_writeb, s);
+    for(i = 0; i < 32; i++) {
+        s->gpe.mems_sts[i] = 0;
+    }
+    memslot_register_hotplug(piix4_memslot_hotplug, &s->dev.qdev);
+
     pci_bus_hotplug(bus, piix4_device_hotplug, &s->dev.qdev);
 }
 
@@ -553,6 +590,54 @@ static void disable_device(PIIX4PMState *s, int slot)
     s->pci0_status.down |= (1 << slot);
 }
 
+static void enable_mem_device(PIIX4PMState *s, int memdevice)
+{
+    struct gpe_regs *g = &s->gpe;
+    s->ar.gpe.sts[0] |= PIIX4_MEM_HOTPLUG_STATUS;
+    g->mems_sts[memdevice/8] |= (1 << (memdevice%8));
+}
+
+static void disable_mem_device(PIIX4PMState *s, int memdevice)
+{
+    struct gpe_regs *g = &s->gpe;
+    s->ar.gpe.sts[0] |= PIIX4_MEM_HOTPLUG_STATUS;
+    g->mems_sts[memdevice/8] &= ~(1 << (memdevice%8));
+}
+
+static void piix4_memslot_eject(uint32_t addr, uint32_t val)
+{
+    uint32_t start = 8 * (addr - MEM_EJ_BASE);
+    uint32_t idx = 0;
+    MemSlotState *s;
+    PIIX4_DPRINTF("memej write %x <= %d\n", addr, val);
+    while (val) {
+        if (val & 1) {
+            s = memslot_find_from_idx(start + idx);
+            assert(s != NULL);
+            memslot_depopulate(s);
+        }
+        val = val >> 1;
+        idx++;
+    }
+}
+
+static int piix4_memslot_hotplug(DeviceState *qdev, SysBusDevice *dev, int
+        add)
+{
+    PIIX4PMState *s = DO_UPCAST(PIIX4PMState, dev,
+                                PCI_DEVICE(qdev));
+    MemSlotState *slot = MEMSLOT(dev);
+
+    if (add) {
+        enable_mem_device(s, slot->idx);
+    }
+    else {
+        disable_mem_device(s, slot->idx);
+    }
+    pm_update_sci(s);
+    return 0;
+}
+
 static int piix4_device_hotplug(DeviceState *qdev, PCIDevice *dev,
 				PCIHotplugState state)
 {
-- 
1.7.9