[PATCH v20 16/30] LoongArch: KVM: Implement update VM id function

[Tianrui Zhao]

Implement kvm check vmid and update vmid, the vmid should be checked before
vcpu enter guest.

Reviewed-by: Bibo Mao <maobibo@xxxxxxxxxxx>
Signed-off-by: Tianrui Zhao <zhaotianrui@xxxxxxxxxxx>
---
 arch/loongarch/kvm/vmid.c | 66 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 arch/loongarch/kvm/vmid.c

diff --git a/arch/loongarch/kvm/vmid.c b/arch/loongarch/kvm/vmid.c
new file mode 100644
index 0000000000..fc25ddc3b7
--- /dev/null
+++ b/arch/loongarch/kvm/vmid.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kvm_host.h>
+#include "trace.h"
+
+static void _kvm_update_vpid(struct kvm_vcpu *vcpu, int cpu)
+{
+	struct kvm_context *context;
+	unsigned long vpid;
+
+	context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
+	vpid = context->vpid_cache + 1;
+	if (!(vpid & vpid_mask)) {
+		/* finish round of 64 bit loop */
+		if (unlikely(!vpid))
+			vpid = vpid_mask + 1;
+
+		/* vpid 0 reserved for root */
+		++vpid;
+
+		/* start new vpid cycle */
+		kvm_flush_tlb_all();
+	}
+
+	context->vpid_cache = vpid;
+	vcpu->arch.vpid = vpid;
+}
+
+void _kvm_check_vmid(struct kvm_vcpu *vcpu)
+{
+	struct kvm_context *context;
+	bool migrated;
+	unsigned long ver, old, vpid;
+	int cpu;
+
+	cpu = smp_processor_id();
+	/*
+	 * Are we entering guest context on a different CPU to last time?
+	 * If so, the vCPU's guest TLB state on this CPU may be stale.
+	 */
+	context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
+	migrated = (vcpu->cpu != cpu);
+
+	/*
+	 * Check if our vpid is of an older version
+	 *
+	 * We also discard the stored vpid if we've executed on
+	 * another CPU, as the guest mappings may have changed without
+	 * hypervisor knowledge.
+	 */
+	ver = vcpu->arch.vpid & ~vpid_mask;
+	old = context->vpid_cache  & ~vpid_mask;
+	if (migrated || (ver != old)) {
+		_kvm_update_vpid(vcpu, cpu);
+		trace_kvm_vpid_change(vcpu, vcpu->arch.vpid);
+		vcpu->cpu = cpu;
+	}
+
+	/* Restore GSTAT(0x50).vpid */
+	vpid = (vcpu->arch.vpid & vpid_mask)
+		<< CSR_GSTAT_GID_SHIFT;
+	change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid);
+}
-- 
2.27.0