From b70d6285f0f7cbb84619ba1758bb0c6d7620eaef Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Tue, 21 Nov 2023 15:52:17 +0530 Subject: [PATCH] lib: sbi: Allow relaxed MMIO writes in device ipi_clear() callback 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 Reported-by: Bo Gan --- lib/sbi/sbi_ipi.c | 16 ++++++++++++++-- lib/utils/ipi/aclint_mswi.c | 2 +- 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/lib/sbi/sbi_ipi.c b/lib/sbi/sbi_ipi.c index 1694a23..0bf446a 100644 --- a/lib/sbi/sbi_ipi.c +++ b/lib/sbi/sbi_ipi.c @@ -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) diff --git a/lib/utils/ipi/aclint_mswi.c b/lib/utils/ipi/aclint_mswi.c index bfd6a45..4ae6bb1 100644 --- a/lib/utils/ipi/aclint_mswi.c +++ b/lib/utils/ipi/aclint_mswi.c @@ -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]); }