riscv: Remove unused members from struct cpu_operations

name is not used anywhere at all. cpu_prepare and cpu_disable do nothing
and always return 0 if implemented.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231121234736.3489608-3-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: cpu_ops_sbi: Add 64bit hartid support on RV64

The hartid can be a 64bit value on RV64 platforms.

Modify the hartid variable type to unsigned long so that it can
hold 64bit value on RV64 platforms.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20220527051743.2829940-2-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: Declare per cpu boot data as static

The per cpu boot data is only used within the cpu_ops_sbi.c. It can
be delcared as static.

Fixes: 9a2451f18663 ("RISC-V: Avoid using per cpu array for ordered booting")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: Add SBI HSM suspend related defines

We add defines related to SBI HSM suspend call and also
update HSM states naming as-per latest SBI specification.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: Add SBI HSM suspend related defines

We add defines related to SBI HSM suspend call and also update HSM states
naming as-per the latest SBI specification.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

RISC-V: Avoid using per cpu array for ordered booting

Currently both order booting and spinwait approach uses a per cpu
array to update stack & task pointer. This approach will not work for the
following cases.
1. If NR_CPUs are configured to be less than highest hart id.
2. A platform has sparse hartid.

This issue can be fixed for ordered booting as the booting cpu brings up
one cpu at a time using SBI HSM extension which has opaque parameter
that is unused until now.

Introduce a common secondary boot data structure that can store the stack
and task pointer. Secondary harts will use this data while booting up
to setup the sp & tp.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: Support cpu hotplug

This patch enable support for cpu hotplug in RISC-V. It uses SBI HSM
extension to online/offline any hart. As a result, the harts are
returned to firmware once they are offline. If the harts are brought
online afterwards, they re-enter Linux kernel as if a secondary hart
booted for the first time. All booting requirements are honored during
this process.

Tested both on QEMU and HighFive Unleashed board with. Test result follows.

---------------------------------------------------
Offline cpu 2
---------------------------------------------------
$ echo 0 > /sys/devices/system/cpu/cpu2/online
[ 32.828684] CPU2: off
$ cat /proc/cpuinfo
processor : 0
hart : 0
isa : rv64imafdcsu
mmu : sv48

processor : 1
hart : 1
isa : rv64imafdcsu
mmu : sv48

processor : 3
hart : 3
isa : rv64imafdcsu
mmu : sv48

processor : 4
hart : 4
isa : rv64imafdcsu
mmu : sv48

processor : 5
hart : 5
isa : rv64imafdcsu
mmu : sv48

processor : 6
hart : 6
isa : rv64imafdcsu
mmu : sv48

processor : 7
hart : 7
isa : rv64imafdcsu
mmu : sv48

---------------------------------------------------
online cpu 2
---------------------------------------------------
$ echo 1 > /sys/devices/system/cpu/cpu2/online
$ cat /proc/cpuinfo
processor : 0
hart : 0
isa : rv64imafdcsu
mmu : sv48

processor : 1
hart : 1
isa : rv64imafdcsu
mmu : sv48

processor : 2
hart : 2
isa : rv64imafdcsu
mmu : sv48

processor : 3
hart : 3
isa : rv64imafdcsu
mmu : sv48

processor : 4
hart : 4
isa : rv64imafdcsu
mmu : sv48

processor : 5
hart : 5
isa : rv64imafdcsu
mmu : sv48

processor : 6
hart : 6
isa : rv64imafdcsu
mmu : sv48

processor : 7
hart : 7
isa : rv64imafdcsu
mmu : sv48

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

RISC-V: Add supported for ordered booting method using HSM

Currently, all harts have to jump Linux in RISC-V. This complicates the
multi-stage boot process as every transient stage also has to ensure all
harts enter to that stage and jump to Linux afterwards. It also obstructs
a clean Kexec implementation.

SBI HSM extension provides alternate solutions where only a single hart
need to boot and enter Linux. The booting hart can bring up secondary
harts one by one afterwards.

Add SBI HSM based cpu_ops that implements an ordered booting method in
RISC-V. This change is also backward compatible with older firmware not
implementing HSM extension. If a latest kernel is used with older
firmware, it will continue to use the default spinning booting method.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>