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lib: sbi: Allow relaxed MMIO writes in device ipi_clear() callback

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Currently, there are no barriers before or after the ipi_clear()
device callback which forces ipi_clear() device callback to always
use non-relaxed MMIO writes.

Instead of above, we use wmb() in after the ipi_clear() device
callback which pairs with the wmb() done before the ipi_send()
device callback. This also allows device ipi_clear() callback
to use relaxed MMIO writes.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reported-by: Bo Gan <ganboing@gmail.com>
This commit is contained in:
Anup Patel 2023-11-21 15:52:17 +05:30 committed by Anup Patel
parent f520256d03
commit b70d6285f0
2 changed files with 15 additions and 3 deletions
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16
lib/sbi/sbi_ipi.c
View File

@ -220,8 +220,7 @@ void sbi_ipi_process(void)
u32 hartindex = sbi_hartid_to_hartindex(current_hartid());
sbi_pmu_ctr_incr_fw(SBI_PMU_FW_IPI_RECVD);
if (ipi_dev && ipi_dev->ipi_clear)
ipi_dev->ipi_clear(hartindex);
sbi_ipi_raw_clear(hartindex);
ipi_type = atomic_raw_xchg_ulong(&ipi_data->ipi_type, 0);
ipi_event = 0;
@ -247,6 +246,8 @@ int sbi_ipi_raw_send(u32 hartindex)
* or MMIO writes done by the ipi_send() device
* callback. This also allows the ipi_send() device
* callback to use relaxed MMIO writes.
*
* This pairs with the wmb() in sbi_ipi_raw_clear().
*/
wmb();
@ -258,6 +259,17 @@ void sbi_ipi_raw_clear(u32 hartindex)
{
if (ipi_dev && ipi_dev->ipi_clear)
ipi_dev->ipi_clear(hartindex);
/*
* Ensure that memory or MMIO writes after this
* function returns are not observed before the
* memory or MMIO writes done by the ipi_clear()
* device callback. This also allows ipi_clear()
* device callback to use relaxed MMIO writes.
*
* This pairs with the wmb() in sbi_ipi_raw_send().
*/
wmb();
}
const struct sbi_ipi_device *sbi_ipi_get_device(void)

2
lib/utils/ipi/aclint_mswi.c
View File

@ -61,7 +61,7 @@ static void mswi_ipi_clear(u32 hart_index)
/* Clear ACLINT IPI */
msip = (void *)mswi->addr;
writel(0, &msip[sbi_hartindex_to_hartid(hart_index) -
writel_relaxed(0, &msip[sbi_hartindex_to_hartid(hart_index) -
mswi->first_hartid]);
}