mirror of
https://github.com/Fishwaldo/opensbi.git
synced 2025-03-15 11:21:45 +00:00
lib: sbi: Simplify wait_for_coldboot() implementation
On QEMU virt machine with large number of HARTs, some of the HARTs randomly fail to come out of wait_for_coldboot() due to one of the following race-conditions: 1) Failing HARTs are not able to acquire the coldboot_lock and update the coldboot_hartmask in wait_for_coldboot() before the coldboot HART acquires the coldboot_lock and sends IPI in wake_coldboot_harts() hence the failing HARTs never receive IPI from the coldboot HART. 2) Failing HARTs acquire the coldbood_lock and update the coldboot_hartmask before coldboot HART does sbi_scratch_init() so the sbi_hartmask_set_hartid() does not update the coldboot_hartmask on the failing HARTs hence they never receive IPI from the coldboot HART. To address this, use a simple busy-loop in wait_for_coldboot() for polling on coldboot_done flag. Signed-off-by: Anup Patel <apatel@ventanamicro.com>
This commit is contained in:
parent
f5375bc15e
commit
beb0cd177f
2 changed files with 8 additions and 68 deletions
|
@ -40,7 +40,11 @@
|
|||
#define smp_wmb() RISCV_FENCE(w,w)
|
||||
|
||||
/* CPU relax for busy loop */
|
||||
#define cpu_relax() asm volatile ("" : : : "memory")
|
||||
#define cpu_relax() \
|
||||
do { \
|
||||
unsigned long __t; \
|
||||
__asm__ __volatile__ ("div %0, %0, zero" : "=r" (__t)); \
|
||||
} while (0)
|
||||
|
||||
/* clang-format on */
|
||||
|
||||
|
|
|
@ -10,7 +10,6 @@
|
|||
#include <sbi/riscv_asm.h>
|
||||
#include <sbi/riscv_atomic.h>
|
||||
#include <sbi/riscv_barrier.h>
|
||||
#include <sbi/riscv_locks.h>
|
||||
#include <sbi/sbi_console.h>
|
||||
#include <sbi/sbi_cppc.h>
|
||||
#include <sbi/sbi_domain.h>
|
||||
|
@ -191,82 +190,19 @@ static void sbi_boot_print_hart(struct sbi_scratch *scratch, u32 hartid)
|
|||
sbi_hart_delegation_dump(scratch, "Boot HART ", " ");
|
||||
}
|
||||
|
||||
static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;
|
||||
static struct sbi_hartmask coldboot_wait_hmask = { 0 };
|
||||
|
||||
static unsigned long coldboot_done;
|
||||
|
||||
static void wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid)
|
||||
{
|
||||
unsigned long saved_mie, cmip;
|
||||
|
||||
if (__smp_load_acquire(&coldboot_done))
|
||||
return;
|
||||
|
||||
/* Save MIE CSR */
|
||||
saved_mie = csr_read(CSR_MIE);
|
||||
|
||||
/* Set MSIE and MEIE bits to receive IPI */
|
||||
csr_set(CSR_MIE, MIP_MSIP | MIP_MEIP);
|
||||
|
||||
/* Acquire coldboot lock */
|
||||
spin_lock(&coldboot_lock);
|
||||
|
||||
/* Mark current HART as waiting */
|
||||
sbi_hartmask_set_hartid(hartid, &coldboot_wait_hmask);
|
||||
|
||||
/* Release coldboot lock */
|
||||
spin_unlock(&coldboot_lock);
|
||||
|
||||
/* Wait for coldboot to finish using WFI */
|
||||
while (!__smp_load_acquire(&coldboot_done)) {
|
||||
do {
|
||||
wfi();
|
||||
cmip = csr_read(CSR_MIP);
|
||||
} while (!(cmip & (MIP_MSIP | MIP_MEIP)));
|
||||
}
|
||||
|
||||
/* Acquire coldboot lock */
|
||||
spin_lock(&coldboot_lock);
|
||||
|
||||
/* Unmark current HART as waiting */
|
||||
sbi_hartmask_clear_hartid(hartid, &coldboot_wait_hmask);
|
||||
|
||||
/* Release coldboot lock */
|
||||
spin_unlock(&coldboot_lock);
|
||||
|
||||
/* Restore MIE CSR */
|
||||
csr_write(CSR_MIE, saved_mie);
|
||||
|
||||
/*
|
||||
* The wait for coldboot is common for both warm startup and
|
||||
* warm resume path so clearing IPI here would result in losing
|
||||
* an IPI in warm resume path.
|
||||
*
|
||||
* Also, the sbi_platform_ipi_init() called from sbi_ipi_init()
|
||||
* will automatically clear IPI for current HART.
|
||||
*/
|
||||
/* Wait for coldboot to finish */
|
||||
while (!__smp_load_acquire(&coldboot_done))
|
||||
cpu_relax();
|
||||
}
|
||||
|
||||
static void wake_coldboot_harts(struct sbi_scratch *scratch, u32 hartid)
|
||||
{
|
||||
u32 i, hartindex = sbi_hartid_to_hartindex(hartid);
|
||||
|
||||
/* Mark coldboot done */
|
||||
__smp_store_release(&coldboot_done, 1);
|
||||
|
||||
/* Acquire coldboot lock */
|
||||
spin_lock(&coldboot_lock);
|
||||
|
||||
/* Send an IPI to all HARTs waiting for coldboot */
|
||||
sbi_hartmask_for_each_hartindex(i, &coldboot_wait_hmask) {
|
||||
if (i == hartindex)
|
||||
continue;
|
||||
sbi_ipi_raw_send(i);
|
||||
}
|
||||
|
||||
/* Release coldboot lock */
|
||||
spin_unlock(&coldboot_lock);
|
||||
}
|
||||
|
||||
static unsigned long entry_count_offset;
|
||||
|
|
Loading…
Add table
Reference in a new issue