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Subject[PATCH v5 05/13] riscv: Only send remote fences when some other CPU is online
Date
If no other CPU is online, a local cache or TLB flush is sufficient.
These checks can be constant-folded when SMP is disabled.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

(no changes since v4)

Changes in v4:
- New patch for v4

arch/riscv/mm/cacheflush.c | 4 +++-
arch/riscv/mm/tlbflush.c | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 47c485bc7df0..f7933ae88a55 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -21,7 +21,9 @@ void flush_icache_all(void)
{
local_flush_icache_all();

- if (riscv_use_sbi_for_rfence())
+ if (num_online_cpus() < 2)
+ return;
+ else if (riscv_use_sbi_for_rfence())
sbi_remote_fence_i(NULL);
else
on_each_cpu(ipi_remote_fence_i, NULL, 1);
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 8cdb082f00ca..69402c260a89 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -78,7 +78,9 @@ static void __ipi_flush_tlb_all(void *info)

void flush_tlb_all(void)
{
- if (riscv_use_sbi_for_rfence())
+ if (num_online_cpus() < 2)
+ local_flush_tlb_all();
+ else if (riscv_use_sbi_for_rfence())
sbi_remote_sfence_vma_asid(NULL, 0, FLUSH_TLB_MAX_SIZE, FLUSH_TLB_NO_ASID);
else
on_each_cpu(__ipi_flush_tlb_all, NULL, 1);
--
2.43.1

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