linux-kernel - Re: [PATCH 6/7] KVM: TDX: Handle TDX PV port I/O hypercall

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Message-ID: <62b3c444-36db-4ac0-bc10-e8d8a5f553c9@linux.intel.com>
Date: Tue, 10 Dec 2024 17:50:33 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Chao Gao <chao.gao@...el.com>
Cc: pbonzini@...hat.com, seanjc@...gle.com, kvm@...r.kernel.org,
 rick.p.edgecombe@...el.com, kai.huang@...el.com, adrian.hunter@...el.com,
 reinette.chatre@...el.com, xiaoyao.li@...el.com,
 tony.lindgren@...ux.intel.com, isaku.yamahata@...el.com,
 yan.y.zhao@...el.com, michael.roth@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] KVM: TDX: Handle TDX PV port I/O hypercall




On 12/10/2024 5:42 PM, Chao Gao wrote:
>> +static int tdx_emulate_io(struct kvm_vcpu *vcpu)
>> +{
>> +	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
>> +	unsigned long val = 0;
>> +	unsigned int port;
>> +	int size, ret;
>> +	bool write;
> ..
>
>> +
>> +	++vcpu->stat.io_exits;
>> +
>> +	size = tdvmcall_a0_read(vcpu);
>> +	write = tdvmcall_a1_read(vcpu);
> a1 (i.e., R13) should be either 0 or 1. Other values are reserved according to
> the GHCI spec. It is not appropriate to cast it to a boolean. For example, if
> R13=2, KVM shouldn't treat it as a write request; instead, this request should
> be rejected.
Right, will fix it.

Thanks!

>> +	port = tdvmcall_a2_read(vcpu);
>> +
>> +	if (size != 1 && size != 2 && size != 4) {
>> +		tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_INVALID_OPERAND);
>> +		return 1;
>> +	}