Re: [RFC PATCH 2/4] ACPI: introduce the mechanism to save/restore ACPI NVS memory

Rafael J. Wysocki
2008-07-03T23:32:39Z

On Thursday, 3 of July 2008, Zhang Rui wrote:
> According to the ACPI spec, ACPI NVS memory region is required to be
> saved/restored by OS during hibernation.
>
> Section 15.3.2 ACPI Spec 3.0b,
> "OSPM will call the _PTS control method some time before entering a sleeping state,
> to allow the platform’s AML code to update this memory image before entering the
> sleeping state. After the system awakes from an S4 state, OSPM will restore this memory
> area and call the _WAK control method to enable the BIOS to reclaim its memory image."
>
> Add the mechanism to save/restore ACPI NVS memory during hibernation.
>
> Note: now Linux save ACPI NVS memory in acpi_hibernation_pre_snapshot, and restore it in
> acpi_hibernation_leave. Both of these functions will be invoked only once during
> the hibernate and resume.
> Note: in Section 14.3 ACPI spec 3.0b, I only get
> "EfiACPIMemoryNVS: The OS and loader must preserve this memory range in
> the working and ACPI S1–S3 states."
> whether we should save/restore this piece of memory is not cleared.
>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
> drivers/acpi/sleep/main.c | 103 +++++++++++++++++++++++++++++++++++++++++++++-
> include/linux/acpi.h | 3 +
> 2 files changed, 104 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/drivers/acpi/sleep/main.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/sleep/main.c 2008-06-30 16:28:56.000000000 +0800
> +++ linux-2.6/drivers/acpi/sleep/main.c 2008-07-01 09:30:36.000000000 +0800
> @@ -15,6 +15,7 @@
> #include <linux/dmi.h>
> #include <linux/device.h>
> #include <linux/suspend.h>
> +#include <linux/highmem.h>
>
> #include <asm/io.h>
>
> @@ -255,11 +256,91 @@
> #endif /* CONFIG_SUSPEND */
>
> #ifdef CONFIG_HIBERNATION
> +
> +/* ACPI NVS memory need to be saved/stored during hibernation */
> +struct nvs_page {
> + unsigned long pfn;
> + void *data;
> + struct list_head node;
> +};
> +static LIST_HEAD(nvs_pages_list);
> +
> +int acpi_mark_nvs_region(unsigned long start, unsigned long end)
> +{
> + struct nvs_page *pos;
> +
> + while (start <= end) {
> + pos = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
> + if (!pos)
> + return -ENOMEM;

I'd prefer to free the already allocated items and make the list empty in this
case, although it will porbably never happen.

> + pos->pfn = start;
> + start++;
> + list_add_tail(&pos->node, &nvs_pages_list);
> + }
> + return 0;
> +}
> +
> +static int acpi_free_nvs_pages(void)
> +{
> + struct nvs_page *pos;
> +
> + list_for_each_entry(pos, &nvs_pages_list, node) {
> + if (!pos->data)
> + break;
> + free_page((long)pos->data);
> + pos->data = NULL;
> + }
> + return 0;
> +}
> +
> +static int acpi_allocate_nvs_pages(void)
> +{
> + struct nvs_page *pos;
> +
> + list_for_each_entry(pos, &nvs_pages_list, node) {
> + pos->data = (void *)__get_free_page(GFP_KERNEL);
> + if (!pos->data) {
> + acpi_free_nvs_pages();
> + return -ENOMEM;
> + }
> + }
> + return 0;
> +}
> +
> +static void acpi_save_nvs_memory(void)
> +{
> + void *kaddr;
> + struct nvs_page *pos;
> +
> + pr_debug("ACPI: Saving ACPI NVS memory\n");
> + list_for_each_entry(pos, &nvs_pages_list, node) {
> + /* nvs page might not have a 'struct page' */
> + kaddr = kmap_atomic_pfn(pos->pfn, KM_USER0);
> + copy_page(pos->data, kaddr);
> + kunmap_atomic(kaddr, KM_USER0);
> + }
> + return;
> +}
> +
> +static void acpi_restore_nvs_memory(void)
> +{
> + void *kaddr;
> + struct nvs_page *pos;
> +
> + pr_debug("ACPI: Restoring ACPI NVS memory\n");
> + list_for_each_entry(pos, &nvs_pages_list, node) {
> + kaddr = kmap_atomic_pfn(pos->pfn, KM_USER0);
> + copy_page(kaddr, pos->data);
> + kunmap_atomic(kaddr, KM_USER0);
> + }
> +}
> +
> static int acpi_hibernation_begin(void)
> {
> acpi_target_sleep_state = ACPI_STATE_S4;
>
> - return 0;
> + /* allocate pages for ACPI NVS memory before swsusp_shrink_memory */
> + return acpi_allocate_nvs_pages();

I think we shouldn't abort hibernation because of that.

This may be an emergency hibernation due to critical battery status and we
surely don't want to about that.

> }
>
> static int acpi_hibernation_prepare(void)
> @@ -274,6 +355,20 @@
> return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
> }
>
> +static int acpi_hibernation_pre_snapshot(void)
> +{
> + int error = acpi_sleep_prepare(ACPI_STATE_S4);
> +
> + if (error) {
> + acpi_target_sleep_state = ACPI_STATE_S0;
> + return error;
> + }
> +
> + acpi_save_nvs_memory();
> +
> + return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
> +}
> +
> static int acpi_hibernation_enter(void)
> {
> acpi_status status = AE_OK;
> @@ -301,6 +396,7 @@
> acpi_enable();
> /* Reprogram control registers and execute _BFS */
> acpi_leave_sleep_state_prep(ACPI_STATE_S4);
> + acpi_restore_nvs_memory();
> }
>
> static void acpi_hibernation_finish(void)
> @@ -321,6 +417,9 @@
> * during a failing transition to the sleep state.
> */
> acpi_target_sleep_state = ACPI_STATE_S0;
> +
> + /* free pages allocated for ACPI NVS memory */
> + acpi_free_nvs_pages();
> }
>
> static int acpi_hibernation_pre_restore(void)
> @@ -340,7 +439,7 @@
> static struct platform_hibernation_ops acpi_hibernation_ops = {
> .begin = acpi_hibernation_begin,
> .end = acpi_hibernation_end,
> - .pre_snapshot = acpi_hibernation_prepare,
> + .pre_snapshot = acpi_hibernation_pre_snapshot,
> .finish = acpi_hibernation_finish,
> .prepare = acpi_hibernation_prepare,
> .enter = acpi_hibernation_enter,
> Index: linux-2.6/include/linux/acpi.h
> ===================================================================
> --- linux-2.6.orig/include/linux/acpi.h 2008-06-30 16:28:56.000000000 +0800
> +++ linux-2.6/include/linux/acpi.h 2008-06-30 16:29:26.000000000 +0800
> @@ -106,6 +106,9 @@
> void acpi_numa_arch_fixup(void);
> #endif
>
> +#ifdef CONFIG_HIBERNATION
> +int acpi_mark_nvs_region(unsigned long, unsigned long);
> +#endif
> #ifdef CONFIG_ACPI_HOTPLUG_CPU
> /* Arch dependent functions for cpu hotplug support */
> int acpi_map_lsapic(acpi_handle handle, int *pcpu);

Thanks,
Rafael
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