Merge patch series "RISC-V Hibernation Support"

Sia Jee Heng <jeeheng.sia@starfivetech.com> says:

This series adds RISC-V Hibernation/suspend to disk support.
Low level Arch functions were created to support hibernation.
swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
cpu state onto the stack, then calling swsusp_save() to save the memory
image.

Arch specific hibernation header is implemented and is utilized by the
arch_hibernation_header_restore() and arch_hibernation_header_save()
functions. The arch specific hibernation header consists of satp, hartid,
and the cpu_resume address. The kernel built version is also need to be
saved into the hibernation image header to making sure only the same
kernel is restore when resume.

swsusp_arch_resume() creates a temporary page table that covering only
the linear map. It copies the restore code to a 'safe' page, then start to
restore the memory image. Once completed, it restores the original
kernel's page table. It then calls into __hibernate_cpu_resume()
to restore the CPU context. Finally, it follows the normal hibernation
path back to the hibernation core.

To enable hibernation/suspend to disk into RISCV, the below config
need to be enabled:
- CONFIG_HIBERNATION
- CONFIG_ARCH_HIBERNATION_HEADER
- CONFIG_ARCH_HIBERNATION_POSSIBLE

At high-level, this series includes the following changes:
1) Change suspend_save_csrs() and suspend_restore_csrs()
   to public function as these functions are common to
   suspend/hibernation. (patch 1)
2) Refactor the common code in the __cpu_resume_enter() function and
   __hibernate_cpu_resume() function. The common code are used by
   hibernation and suspend. (patch 2)
3) Enhance kernel_page_present() function to support huge page. (patch 3)
4) Add arch/riscv low level functions to support
   hibernation/suspend to disk. (patch 4)

* b4-shazam-merge:
  RISC-V: Add arch functions to support hibernation/suspend-to-disk
  RISC-V: mm: Enable huge page support to kernel_page_present() function
  RISC-V: Factor out common code of __cpu_resume_enter()
  RISC-V: Change suspend_save_csrs and suspend_restore_csrs to public function

Link: https://lore.kernel.org/r/20230330064321.1008373-1-jeeheng.sia@starfivetech.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 7f4c5580753e..146ecd5f6a56 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -55,7 +55,7 @@ config RISCV
 	select CLINT_TIMER if !MMU
 	select CLONE_BACKWARDS
 	select COMMON_CLK
-	select CPU_PM if CPU_IDLE
+	select CPU_PM if CPU_IDLE || HIBERNATION
 	select EDAC_SUPPORT
 	select GENERIC_ARCH_TOPOLOGY
 	select GENERIC_ATOMIC64 if !64BIT
@@ -799,6 +799,12 @@ menu "Power management options"
 
 source "kernel/power/Kconfig"
 
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+
+config ARCH_HIBERNATION_HEADER
+	def_bool HIBERNATION
+
 endmenu # "Power management options"
 
 menu "CPU Power Management"