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

[赵天瑞]

> -----原始邮件-----
> 发件人: "Youling Tang" <tangyouling@xxxxxxxxxxx>
> 发送时间:2023-06-06 15:00:11 (星期二)
> 收件人: "Tianrui Zhao" <zhaotianrui@xxxxxxxxxxx>
> 抄送: linux-kernel@xxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, "Paolo Bonzini" <pbonzini@xxxxxxxxxx>, "Huacai Chen" <chenhuacai@xxxxxxxxxx>, "WANG Xuerui" <kernel@xxxxxxxxxx>, "Greg Kroah-Hartman" <gregkh@xxxxxxxxxxxxxxxxxxx>, loongarch@xxxxxxxxxxxxxxx, "Jens Axboe" <axboe@xxxxxxxxx>, "Mark Brown" <broonie@xxxxxxxxxx>, "Alex Deucher" <alexander.deucher@xxxxxxx>, "Oliver Upton" <oliver.upton@xxxxxxxxx>, maobibo@xxxxxxxxxxx, "Xi Ruoyao" <xry111@xxxxxxxxxxx>
> 主题: Re: [PATCH v12 26/31] LoongArch: KVM: Implement kvm exception vector
> 
> 
> 
> 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@xxxxxxxxxxx>
> > ---
> >  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
Hi Youling,
When I compile this code with W=1, there is a warning: initialized field overwritten [-Woverride-init], so considering this problem I think we have to keep the previous _kvm_init_fault, what do you think of 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;
> > +}
> >


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