[RFC] KVM: arm64: Don't force broadcast tlbi when guest is running

[Shaokun Zhang]

From: Nianyao Tang <tangnianyao at huawei.com>

Now HCR_EL2.FB is set to force broadcast tlbi to all online pcpus,
even those vcpu do not resident on. It would get worse as system
gets larger and more pcpus get online.
Let's disable force-broadcast. We flush tlbi when move vcpu to a
new pcpu, in case old page mapping still exists on new pcpu.

Cc: Marc Zyngier <maz at kernel.org>
Signed-off-by: Nianyao Tang <tangnianyao at huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun at hisilicon.com>
---
 arch/arm64/include/asm/kvm_arm.h | 2 +-
 arch/arm64/kvm/arm.c             | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 64ce29378467..f85ea9c649cb 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -75,7 +75,7 @@
  * PTW:		Take a stage2 fault if a stage1 walk steps in device memory
  */
 #define HCR_GUEST_FLAGS (HCR_TSC | HCR_TSW | HCR_TWE | HCR_TWI | HCR_VM | \
-			 HCR_BSU_IS | HCR_FB | HCR_TAC | \
+			 HCR_BSU_IS | HCR_TAC | \
 			 HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
 			 HCR_FMO | HCR_IMO | HCR_PTW )
 #define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index acf9a993dfb6..845be911f885 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -334,8 +334,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	/*
 	 * We might get preempted before the vCPU actually runs, but
 	 * over-invalidation doesn't affect correctness.
+	 * Dirty tlb might still exist when vcpu ran on other pcpu
+	 * and modified page mapping.
 	 */
-	if (*last_ran != vcpu->vcpu_id) {
+	if (*last_ran != vcpu->vcpu_id || vcpu->cpu != cpu) {
 		kvm_call_hyp(__kvm_tlb_flush_local_vmid, mmu);
 		*last_ran = vcpu->vcpu_id;
 	}
-- 
2.7.4