linux-kernel - Re: [PATCH v7 16/30] LoongArch: KVM: Implement update VM id function

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Message-ID: <d2dbcf54-4015-81ec-6b96-47cdcc22cd13@loongson.cn>
Date:   Wed, 19 Apr 2023 16:53:38 +0800
From:   Tianrui Zhao <zhaotianrui@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        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,
        Xi Ruoyao <xry111@...111.site>
Subject: Re: [PATCH v7 16/30] LoongArch: KVM: Implement update VM id function



在 2023年04月19日 10:01, Huacai Chen 写道:
> Hi, Tianrui,
>
> On Mon, Apr 17, 2023 at 5:47 PM Tianrui Zhao <zhaotianrui@...ngson.cn> wrote:
>> 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 | 65 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 65 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 000000000000..7d9688c24184
>> --- /dev/null
>> +++ b/arch/loongarch/kvm/vmid.c
>> @@ -0,0 +1,65 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
>> + */
>> +
>> +#include <linux/kvm_host.h>
>> +#include <asm/kvm_host.h>
> linux/kvm_host.h already include asm/kvm_host.h
>
> Huacai
Thanks, I will remove the asm/kvm_host.h.

Thanks
Tianrui Zhao
>> +#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, 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 & ~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);
>> +       }
>> +
>> +       /* Restore GSTAT(0x50).vpid */
>> +       vpid = (vcpu->arch.vpid & vpid_mask)
>> +               << CSR_GSTAT_GID_SHIFT;
>> +       change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid);
>> +}
>> --
>> 2.31.1
>>