linux-kernel - Re: [PATCH v12 21/31] LoongArch: KVM: Implement handle iocsr exception

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Date:   Tue, 6 Jun 2023 09:36:16 +0800
From:   "bibo, mao" <maobibo@...ngson.cn>
To:     Tianrui Zhao <zhaotianrui@...ngson.cn>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     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>,
        Xi Ruoyao <xry111@...111.site>
Subject: Re: [PATCH v12 21/31] LoongArch: KVM: Implement handle iocsr
 exception

Reviewed-by: Bibo, Mao <maobibo@...ngson.cn>

在 2023/5/30 09:52, Tianrui Zhao 写道:
> Implement kvm handle vcpu iocsr exception, setting the iocsr info into
> vcpu_run and return to user space to handle it.
> 
> Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
> ---
>  arch/loongarch/include/asm/inst.h | 16 ++++++
>  arch/loongarch/kvm/exit.c         | 92 +++++++++++++++++++++++++++++++
>  2 files changed, 108 insertions(+)
> 
> diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
> index b09887ffcd15..db5857796432 100644
> --- a/arch/loongarch/include/asm/inst.h
> +++ b/arch/loongarch/include/asm/inst.h
> @@ -56,6 +56,14 @@ enum reg2_op {
>  	revbd_op	= 0x0f,
>  	revh2w_op	= 0x10,
>  	revhd_op	= 0x11,
> +	iocsrrdb_op     = 0x19200,
> +	iocsrrdh_op     = 0x19201,
> +	iocsrrdw_op     = 0x19202,
> +	iocsrrdd_op     = 0x19203,
> +	iocsrwrb_op     = 0x19204,
> +	iocsrwrh_op     = 0x19205,
> +	iocsrwrw_op     = 0x19206,
> +	iocsrwrd_op     = 0x19207,
>  };
>  
>  enum reg2i5_op {
> @@ -298,6 +306,13 @@ struct reg3sa2_format {
>  	unsigned int opcode : 15;
>  };
>  
> +struct reg2csr_format {
> +	unsigned int rd : 5;
> +	unsigned int rj : 5;
> +	unsigned int csr : 14;
> +	unsigned int opcode : 8;
> +};
> +
>  union loongarch_instruction {
>  	unsigned int word;
>  	struct reg0i15_format	reg0i15_format;
> @@ -313,6 +328,7 @@ union loongarch_instruction {
>  	struct reg2bstrd_format	reg2bstrd_format;
>  	struct reg3_format	reg3_format;
>  	struct reg3sa2_format	reg3sa2_format;
> +	struct reg2csr_format   reg2csr_format;
>  };
>  
>  #define LOONGARCH_INSN_SIZE	sizeof(union loongarch_instruction)
> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
> index 508cbce31aa5..bd33fe0c6424 100644
> --- a/arch/loongarch/kvm/exit.c
> +++ b/arch/loongarch/kvm/exit.c
> @@ -96,3 +96,95 @@ static int _kvm_handle_csr(struct kvm_vcpu *vcpu, larch_inst inst)
>  
>  	return EMULATE_DONE;
>  }
> +
> +int _kvm_emu_iocsr(larch_inst inst, struct kvm_run *run, struct kvm_vcpu *vcpu)
> +{
> +	u32 rd, rj, opcode;
> +	u32 addr;
> +	unsigned long val;
> +	int ret;
> +
> +	/*
> +	 * Each IOCSR with different opcode
> +	 */
> +	rd = inst.reg2_format.rd;
> +	rj = inst.reg2_format.rj;
> +	opcode = inst.reg2_format.opcode;
> +	addr = vcpu->arch.gprs[rj];
> +	ret = EMULATE_DO_IOCSR;
> +	run->iocsr_io.phys_addr = addr;
> +	run->iocsr_io.is_write = 0;
> +
> +	/* LoongArch is Little endian */
> +	switch (opcode) {
> +	case iocsrrdb_op:
> +		run->iocsr_io.len = 1;
> +		break;
> +	case iocsrrdh_op:
> +		run->iocsr_io.len = 2;
> +		break;
> +	case iocsrrdw_op:
> +		run->iocsr_io.len = 4;
> +		break;
> +	case iocsrrdd_op:
> +		run->iocsr_io.len = 8;
> +		break;
> +	case iocsrwrb_op:
> +		run->iocsr_io.len = 1;
> +		run->iocsr_io.is_write = 1;
> +		break;
> +	case iocsrwrh_op:
> +		run->iocsr_io.len = 2;
> +		run->iocsr_io.is_write = 1;
> +		break;
> +	case iocsrwrw_op:
> +		run->iocsr_io.len = 4;
> +		run->iocsr_io.is_write = 1;
> +		break;
> +	case iocsrwrd_op:
> +		run->iocsr_io.len = 8;
> +		run->iocsr_io.is_write = 1;
> +		break;
> +	default:
> +		ret = EMULATE_FAIL;
> +		break;
> +	}
> +
> +	if (ret == EMULATE_DO_IOCSR) {
> +		if (run->iocsr_io.is_write) {
> +			val = vcpu->arch.gprs[rd];
> +			memcpy(run->iocsr_io.data, &val, run->iocsr_io.len);
> +		}
> +		vcpu->arch.io_gpr = rd;
> +	}
> +
> +	return ret;
> +}
> +
> +int _kvm_complete_iocsr_read(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	unsigned long *gpr = &vcpu->arch.gprs[vcpu->arch.io_gpr];
> +	enum emulation_result er = EMULATE_DONE;
> +
> +	switch (run->iocsr_io.len) {
> +	case 8:
> +		*gpr = *(s64 *)run->iocsr_io.data;
> +		break;
> +	case 4:
> +		*gpr = *(int *)run->iocsr_io.data;
> +		break;
> +	case 2:
> +		*gpr = *(short *)run->iocsr_io.data;
> +		break;
> +	case 1:
> +		*gpr = *(char *) run->iocsr_io.data;
> +		break;
> +	default:
> +		kvm_err("Bad IOCSR length: %d,addr is 0x%lx",
> +				run->iocsr_io.len, vcpu->arch.badv);
> +		er = EMULATE_FAIL;
> +		break;
> +	}
> +
> +	return er;
> +}