linux-kernel - Re: [RFC PATCH 10/16] RISC-V: KVM: Implement VMID allocator

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Message-ID: <4a99b586-a7bb-be3e-c47b-7809e6be610b@redhat.com>
Date:   Tue, 30 Jul 2019 10:59:08 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Anup Patel <Anup.Patel@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Radim K <rkrcmar@...hat.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Atish Patra <Atish.Patra@....com>,
        Alistair Francis <Alistair.Francis@....com>,
        Damien Le Moal <Damien.LeMoal@....com>,
        Christoph Hellwig <hch@...radead.org>,
        Anup Patel <anup@...infault.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 10/16] RISC-V: KVM: Implement VMID allocator

On 29/07/19 13:57, Anup Patel wrote:
> +	/* First user of a new VMID version? */
> +	if (unlikely(vmid_next == 0)) {
> +		atomic_long_inc(&vmid_version);
> +		vmid_next = 1;
> +

vmid_version is only written under vmid_lock, so it doesn't need to be
atomic.  You only need WRITE_ONCE/READ_ONCE.

> +
> +	/* Request stage2 page table update for all VCPUs */
> +	kvm_for_each_vcpu(i, v, vcpu->kvm)
> +		kvm_make_request(KVM_REQ_UPDATE_PGTBL, v);

Perhaps rename kvm_riscv_stage2_update_pgtbl and KVM_REQ_UPDATE_PGTBL to
kvm_riscv_update_hgatp and KVM_REQ_UPDATE_HGATP?

Paolo