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/*
* Virtual Machine Clock Device
*
* Copyright © 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Authors: David Woodhouse <dwmw2@infradead.org>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/module.h"
#include "hw/i386/e820_memory_layout.h"
#include "hw/acpi/acpi.h"
#include "hw/acpi/aml-build.h"
#include "hw/acpi/vmclock.h"
#include "hw/nvram/fw_cfg.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "migration/vmstate.h"
#include "system/reset.h"
#include "standard-headers/linux/vmclock-abi.h"
void vmclock_build_acpi(VmclockState *vms, GArray *table_data,
BIOSLinker *linker, const char *oem_id)
{
Aml *ssdt, *dev, *scope, *crs;
AcpiTable table = { .sig = "SSDT", .rev = 1,
.oem_id = oem_id, .oem_table_id = "VMCLOCK" };
/* Put VMCLOCK into a separate SSDT table */
acpi_table_begin(&table, table_data);
ssdt = init_aml_allocator();
scope = aml_scope("\\_SB");
dev = aml_device("VCLK");
aml_append(dev, aml_name_decl("_HID", aml_string("AMZNC10C")));
aml_append(dev, aml_name_decl("_CID", aml_string("VMCLOCK")));
aml_append(dev, aml_name_decl("_DDN", aml_string("VMCLOCK")));
/* Simple status method */
aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
crs = aml_resource_template();
aml_append(crs, aml_qword_memory(AML_POS_DECODE,
AML_MIN_FIXED, AML_MAX_FIXED,
AML_CACHEABLE, AML_READ_ONLY,
0xffffffffffffffffULL,
vms->physaddr,
vms->physaddr + VMCLOCK_SIZE - 1,
0, VMCLOCK_SIZE));
aml_append(dev, aml_name_decl("_CRS", crs));
aml_append(scope, dev);
aml_append(ssdt, scope);
g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
acpi_table_end(linker, &table);
free_aml_allocator();
}
static void vmclock_update_guest(VmclockState *vms)
{
uint64_t disruption_marker;
uint32_t seq_count;
if (!vms->clk) {
return;
}
seq_count = le32_to_cpu(vms->clk->seq_count) | 1;
vms->clk->seq_count = cpu_to_le32(seq_count);
/* These barriers pair with read barriers in the guest */
smp_wmb();
disruption_marker = le64_to_cpu(vms->clk->disruption_marker);
disruption_marker++;
vms->clk->disruption_marker = cpu_to_le64(disruption_marker);
/* These barriers pair with read barriers in the guest */
smp_wmb();
vms->clk->seq_count = cpu_to_le32(seq_count + 1);
}
/*
* After restoring an image, we need to update the guest memory to notify
* it of clock disruption.
*/
static int vmclock_post_load(void *opaque, int version_id)
{
VmclockState *vms = opaque;
vmclock_update_guest(vms);
return 0;
}
static const VMStateDescription vmstate_vmclock = {
.name = "vmclock",
.version_id = 1,
.minimum_version_id = 1,
.post_load = vmclock_post_load,
.fields = (const VMStateField[]) {
VMSTATE_UINT64(physaddr, VmclockState),
VMSTATE_END_OF_LIST()
},
};
static void vmclock_handle_reset(void *opaque)
{
VmclockState *vms = VMCLOCK(opaque);
if (!memory_region_is_mapped(&vms->clk_page)) {
memory_region_add_subregion_overlap(get_system_memory(),
vms->physaddr,
&vms->clk_page, 0);
}
}
static void vmclock_realize(DeviceState *dev, Error **errp)
{
VmclockState *vms = VMCLOCK(dev);
/*
* Given that this function is executing, there is at least one VMCLOCK
* device. Check if there are several.
*/
if (!find_vmclock_dev()) {
error_setg(errp, "at most one %s device is permitted", TYPE_VMCLOCK);
return;
}
vms->physaddr = VMCLOCK_ADDR;
e820_add_entry(vms->physaddr, VMCLOCK_SIZE, E820_RESERVED);
memory_region_init_ram(&vms->clk_page, OBJECT(dev), "vmclock_page",
VMCLOCK_SIZE, &error_abort);
memory_region_set_enabled(&vms->clk_page, true);
vms->clk = memory_region_get_ram_ptr(&vms->clk_page);
memset(vms->clk, 0, VMCLOCK_SIZE);
vms->clk->magic = cpu_to_le32(VMCLOCK_MAGIC);
vms->clk->size = cpu_to_le16(VMCLOCK_SIZE);
vms->clk->version = cpu_to_le16(1);
/* These are all zero and thus default, but be explicit */
vms->clk->clock_status = VMCLOCK_STATUS_UNKNOWN;
vms->clk->counter_id = VMCLOCK_COUNTER_INVALID;
qemu_register_reset(vmclock_handle_reset, vms);
vmclock_update_guest(vms);
}
static void vmclock_device_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->vmsd = &vmstate_vmclock;
dc->realize = vmclock_realize;
dc->hotpluggable = false;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
}
static const TypeInfo vmclock_device_info = {
.name = TYPE_VMCLOCK,
.parent = TYPE_DEVICE,
.instance_size = sizeof(VmclockState),
.class_init = vmclock_device_class_init,
};
static void vmclock_register_types(void)
{
type_register_static(&vmclock_device_info);
}
type_init(vmclock_register_types)
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