[PATCH v5 3/5] RISC-V: KVM: Remove redundant TLB flush operations

[Wang Yechao]

The function kvm_arch_mmu_enable_log_dirty_pt_masked() is invoked from
two distinct call paths:

kvm_clear_dirty_log_protect()
  kvm_arch_mmu_enable_log_dirty_pt_masked()

kvm_vm_ioctl_reset_dirty_pages()
  kvm_dirty_ring_reset()
    kvm_reset_dirty_gfn()
        kvm_arch_mmu_enable_log_dirty_pt_masked()

In both scenarios, the caller already performs a remote TLB flush after
dirty logging is enabled, so the TLB flush inside
kvm_arch_mmu_enable_log_dirty_pt_masked() is unnecessary. Remove it.

Signed-off-by: Wang Yechao <wang.yechao255@xxxxxxxxxx>
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
---
 arch/riscv/kvm/mmu.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 2362eeb6c08a5..5a93cffa9ad7f 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -163,14 +163,15 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 	phys_addr_t start = (base_gfn +  __ffs(mask)) << PAGE_SHIFT;
 	phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
 	struct kvm_gstage gstage;
-	bool flush;
 
 	kvm_riscv_gstage_init(&gstage, kvm);
 
-	flush = kvm_riscv_gstage_wp_range(&gstage, start, end);
-	if (flush)
-		kvm_flush_remote_tlbs_range(kvm, start >> PAGE_SHIFT,
-					    (end - start) >> PAGE_SHIFT);
+	kvm_riscv_gstage_wp_range(&gstage, start, end);
+
+	/*
+	 * remote TLB flush is not needed here since callers of
+	 * kvm_arch_mmu_enable_log_dirty_pt_masked() already do it.
+	 */
 }
 
 void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
-- 
2.39.3