[PATCH 5/6] LoongArch: KVM: Add remote tlb flushing support

[Bibo Mao]

With remote tlb flushing, vpid index stays unchanged and only vmid
index is updated, since remote tlb flushing is to flush TLBs relative
GPA --> HPA.

For flushing method, cpumask tlb_flush_pending is added and set for
all possible CPUs. When vCPUs is sched on the physical CPU, vmid is
updated and cpumask for this physical CPU is cleared.

Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/loongarch/include/asm/kvm_host.h |  3 +++
 arch/loongarch/kvm/main.c             |  2 ++
 arch/loongarch/kvm/mmu.c              | 16 ++++++++++++++++
 arch/loongarch/kvm/vcpu.c             |  7 ++++++-
 4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index a01623c42c7a..2c3cb475abf9 100644
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -133,6 +133,7 @@ struct kvm_arch {
 	unsigned long kvm_features;
 
 	s64 time_offset;
+	cpumask_t tlb_flush_pending;
 	unsigned long vmid[NR_CPUS];
 	struct kvm_context __percpu *vmcs;
 	struct loongarch_ipi *ipi;
@@ -357,6 +358,8 @@ static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) {}
 void kvm_check_vpid(struct kvm_vcpu *vcpu);
 enum hrtimer_restart kvm_swtimer_wakeup(struct hrtimer *timer);
+#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS
+int kvm_arch_flush_remote_tlbs(struct kvm *kvm);
 void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, const struct kvm_memory_slot *memslot);
 void kvm_init_vmcs(struct kvm *kvm);
 void kvm_exc_entry(void);
diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
index 7b3661da8958..86b1af823e2b 100644
--- a/arch/loongarch/kvm/main.c
+++ b/arch/loongarch/kvm/main.c
@@ -322,6 +322,8 @@ static void kvm_check_vmid(struct kvm_vcpu *vcpu)
 
 	cpu = smp_processor_id();
 	context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
+	if (cpumask_test_and_clear_cpu(cpu, &vcpu->kvm->arch.tlb_flush_pending))
+		vcpu->kvm->arch.vmid[cpu] = 0;
 
 	/*
 	 * Check if our vmid is of an older version
diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
index e104897aa532..560a2d0f111f 100644
--- a/arch/loongarch/kvm/mmu.c
+++ b/arch/loongarch/kvm/mmu.c
@@ -940,6 +940,22 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
 }
 
+int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
+{
+	/*
+	 * Queue a TLB invalidation for each CPU to perform on next
+	 * vcpu loading
+	 */
+	if (cpu_has_guestid) {
+		cpumask_setall(&kvm->arch.tlb_flush_pending);
+		/* Be sure that other CPUS can watch the changes */
+		smp_wmb();
+	}
+
+	/* Return 1 continue to send ipi to running vCPUs */
+	return 1;
+}
+
 void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
 					const struct kvm_memory_slot *memslot)
 {
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 20c207d80e31..19c81ae8941a 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -210,7 +210,12 @@ static int kvm_check_requests(struct kvm_vcpu *vcpu)
 		return RESUME_GUEST;
 
 	if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu))
-		vcpu->arch.vpid = 0;  /* Drop vpid for this vCPU */
+		/*
+		 * vpid need the same with vmid if vpid is not separated
+		 * with vmid
+		 */
+		if (!cpu_has_guestid)
+			vcpu->arch.vpid = 0;  /* Drop vpid for this vCPU */
 
 	if (kvm_dirty_ring_check_request(vcpu))
 		return RESUME_HOST;
-- 
2.39.3