linux-kernel - Re: [PATCH v12 26/31] LoongArch: KVM: Implement kvm exception vector

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Date:   Tue, 6 Jun 2023 17:16:38 +0800
From:   Tianrui Zhao <zhaotianrui@...ngson.cn>
To:     Youling Tang <tangyouling@...ngson.cn>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        loongarch@...ts.linux.dev, 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 v12 26/31] LoongArch: KVM: Implement kvm exception vector



在 2023年06月06日 15:00, Youling Tang 写道:
>
>
> On 05/30/2023 09:52 AM, Tianrui Zhao wrote:
>> Implement kvm exception vector, using _kvm_fault_tables array to save
>> the handle function pointer and it is used when vcpu handle exit.
>>
>> Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
>> ---
>>  arch/loongarch/kvm/exit.c | 48 +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 48 insertions(+)
>>
>> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
>> index 10f9922a7e76..625045fc95c8 100644
>> --- a/arch/loongarch/kvm/exit.c
>> +++ b/arch/loongarch/kvm/exit.c
>> @@ -657,3 +657,51 @@ static int _kvm_handle_fpu_disabled(struct 
>> kvm_vcpu *vcpu)
>>      kvm_own_fpu(vcpu);
>>      return RESUME_GUEST;
>>  }
>> +
>> +/*
>> + * Loongarch KVM callback handling for not implemented guest exiting
>> + */
>> +static int _kvm_fault_ni(struct kvm_vcpu *vcpu)
>> +{
>> +    unsigned long estat, badv;
>> +    unsigned int exccode, inst;
>> +
>> +    /*
>> +     *  Fetch the instruction.
>> +     */
>> +    badv = vcpu->arch.badv;
>> +    estat = vcpu->arch.host_estat;
>> +    exccode = (estat & CSR_ESTAT_EXC) >> CSR_ESTAT_EXC_SHIFT;
>> +    inst = vcpu->arch.badi;
>> +    kvm_err("Exccode: %d PC=%#lx inst=0x%08x BadVaddr=%#lx 
>> estat=%#lx\n",
>> +            exccode, vcpu->arch.pc, inst, badv, read_gcsr_estat());
>> +    kvm_arch_vcpu_dump_regs(vcpu);
>> +    vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>> +
>> +    return RESUME_HOST;
>> +}
>> +
>> +static exit_handle_fn _kvm_fault_tables[EXCCODE_INT_START] = {
>> +    [EXCCODE_TLBL]        = _kvm_handle_read_fault,
>> +    [EXCCODE_TLBI]        = _kvm_handle_read_fault,
>> +    [EXCCODE_TLBNR]        = _kvm_handle_read_fault,
>> +    [EXCCODE_TLBNX]        = _kvm_handle_read_fault,
>> +    [EXCCODE_TLBS]        = _kvm_handle_write_fault,
>> +    [EXCCODE_TLBM]        = _kvm_handle_write_fault,
>> +    [EXCCODE_FPDIS]        = _kvm_handle_fpu_disabled,
>> +    [EXCCODE_GSPR]        = _kvm_handle_gspr,
>> +};
> It can be modified as follows and remove _kvm_init_fault().
>
> static exit_handle_fn _kvm_fault_tables[EXCCODE_INT_START] = {
>     [0 ... EXCCODE_INT_START - 1]    = _kvm_fault_ni,
>
>     [EXCCODE_TLBL]            = _kvm_handle_read_fault,
>     [EXCCODE_TLBI]            = _kvm_handle_read_fault,
>     [EXCCODE_TLBNR]            = _kvm_handle_read_fault,
>     [EXCCODE_TLBNX]            = _kvm_handle_read_fault,
>     [EXCCODE_TLBS]            = _kvm_handle_write_fault,
>     [EXCCODE_TLBM]            = _kvm_handle_write_fault,
>     [EXCCODE_FPDIS]            = _kvm_handle_fpu_disabled,
>     [EXCCODE_GSPR]            = _kvm_handle_gspr,
> };
>
> Thanks,
> Youling
Thanks, this method can simplify the code, I will fix it.

Thanks
Tianrui Zhao
>
>> +
>> +int _kvm_handle_fault(struct kvm_vcpu *vcpu, int fault)
>> +{
>> +    return _kvm_fault_tables[fault](vcpu);
>> +}
>> +
>> +void _kvm_init_fault(void)
>> +{
>> +    int i;
>> +
>> +    for (i = 0; i < EXCCODE_INT_START; i++)
>> +        if (!_kvm_fault_tables[i])
>> +            _kvm_fault_tables[i] = _kvm_fault_ni;
>> +}
>>