[Qemu-devel] [RFC PATCH 6/6] KVM: ARM: no need for kvm_arch_flush_incoherent

[Andrew Jones]

kvm_arch_flush_incoherent makes things too slow, and we don't
need it. Userspace can flush for us, as the necessary cache
maintenance instruction is not (necessarily) privileged.

Signed-off-by: Andrew Jones <address@hidden>
---
 arch/arm/kvm/mmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 2f45db9cd436a..b2d87587a9d79 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -1822,6 +1822,11 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct 
kvm_memory_slot *slot,
 
 void kvm_arch_flush_incoherent(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
+       /*
+        * We no longer need this function, now that userspace does the
+        * flushing.
+        */
+#if 0
        if (slot->flags & KVM_MEM_READONLY) {
                /*
                 * Readonly memory shouldn't be changing, and we do a
@@ -1840,6 +1845,7 @@ void kvm_arch_flush_incoherent(struct kvm *kvm, struct 
kvm_memory_slot *slot)
         */
 
        coherent_cache_memslot(slot, true);
+#endif
 }
 
 void kvm_arch_invalidate_incoherent(struct kvm *kvm, struct kvm_memory_slot 
*slot)
-- 
1.8.3.1