linux/arch/riscv
Greentime Hu 3384b043ea
riscv: fix the IPI missing issue in nommu mode
This patch fixes the IPI(inner processor interrupt) missing issue. It
failed because it used hartid_mask to iterate for_each_cpu(), however the
cpu_mask and hartid_mask may not be always the same. It will never send the
IPI to hartid 4 because it will be skipped in for_each_cpu loop in my case.

We can reproduce this case in Qemu sifive_u machine by this command.
qemu-system-riscv64 -nographic -smp 5 -m 1G -M sifive_u -kernel \
arch/riscv/boot/loader

It will hang in csd_lock_wait(csd) because the csd_unlock(csd) is not
called. It is not called because hartid 4 doesn't receive the IPI to
release this lock. The caller hart doesn't send the IPI to hartid 4 is
because of hartid 4 is skipped in for_each_cpu(). It will be skipped is
because "(cpu) < nr_cpu_ids" is not true. The hartid is 4 and nr_cpu_ids
is 4. Therefore it should use cpumask in for_each_cpu() instead of
hartid_mask.

        /* Send a message to all CPUs in the map */
        arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

        if (wait) {
                for_each_cpu(cpu, cfd->cpumask) {
                        call_single_data_t *csd;
			csd = per_cpu_ptr(cfd->csd, cpu);
                        csd_lock_wait(csd);
                }
        }

        for ((cpu) = -1;                                \
                (cpu) = cpumask_next((cpu), (mask)),    \
                (cpu) < nr_cpu_ids;)

It could boot to login console after this patch applied.

Fixes: b2d36b5668f6 ("riscv: provide native clint access for M-mode")
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-03-18 18:44:39 -07:00
..
boot riscv: dts: Add GPIO reboot method to HiFive Unleashed DTS file 2020-03-05 12:27:10 -08:00
configs RISC-V: Select Goldfish RTC driver for QEMU virt machine 2020-03-05 10:48:46 -08:00
include riscv: fix the IPI missing issue in nommu mode 2020-03-18 18:44:39 -07:00
kernel riscv: fix the IPI missing issue in nommu mode 2020-03-18 18:44:39 -07:00
lib riscv: uaccess should be used in nommu mode 2020-03-18 18:44:30 -07:00
mm riscv: Fix range looking for kernel image memblock 2020-03-04 15:11:03 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-12-27 14:20:10 -08:00
Kbuild riscv: add arch/riscv/Kbuild 2019-08-30 17:34:00 -07:00
Kconfig riscv: uaccess should be used in nommu mode 2020-03-18 18:44:30 -07:00
Kconfig.debug RISC-V: Remove EARLY_PRINTK support 2018-12-17 10:23:46 -08:00
Kconfig.socs RISC-V: Select Goldfish RTC driver for QEMU virt machine 2020-03-05 10:48:46 -08:00
Makefile riscv: Change code model of module to medany to improve data accessing 2020-03-03 10:27:46 -08:00