linux-kernel - [PATCH v2 16/29] LoongArch: KVM: Implement update VM id function

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Date:   Mon, 20 Feb 2023 14:57:22 +0800
From:   Tianrui Zhao <zhaotianrui@...ngson.cn>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Mark Brown <broonie@...nel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn
Subject: [PATCH v2 16/29] LoongArch: KVM: Implement update VM id function

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

Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
---
 arch/loongarch/kvm/vmid.c | 64 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 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 000000000..82729968e
--- /dev/null
+++ b/arch/loongarch/kvm/vmid.c
@@ -0,0 +1,64 @@
+// 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 & context->vpid_mask)) {
+		/* finish round of 64 bit loop */
+		if (unlikely(!vpid))
+			vpid = context->vpid_mask + 1;
+
+		/* vpid 0 reserved for root */
+		++vpid;
+
+		/* start new vpid cycle */
+		kvm_flush_tlb_all();
+	}
+
+	context->vpid_cache = vpid;
+	vcpu->arch.vpid[cpu] = vpid;
+}
+
+void _kvm_check_vmid(struct kvm_vcpu *vcpu, int cpu)
+{
+	struct kvm_context *context;
+	bool migrated;
+	unsigned long ver, old, vpid;
+
+	/*
+	 * 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->arch.last_exec_cpu != cpu);
+	vcpu->arch.last_exec_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[cpu] & ~context->vpid_mask;
+	old = context->vpid_cache  & ~context->vpid_mask;
+	if (migrated || (ver != old)) {
+		_kvm_update_vpid(vcpu, cpu);
+		trace_kvm_vpid_change(vcpu, vcpu->arch.vpid[cpu]);
+	}
+
+	/* Restore GSTAT(0x50).vpid */
+	vpid = (vcpu->arch.vpid[cpu] & context->vpid_mask)
+		<< CSR_GSTAT_GID_SHIFT;
+	change_csr_gstat(context->vpid_mask << CSR_GSTAT_GID_SHIFT, vpid);
+}
-- 
2.31.1