linux-kernel - Re: [PATCH v19 078/130] KVM: TDX: Implement TDX vcpu enter/exit path

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Date: Sun, 7 Apr 2024 09:42:23 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: isaku.yamahata@...el.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
 Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com
Subject: Re: [PATCH v19 078/130] KVM: TDX: Implement TDX vcpu enter/exit path



On 3/16/2024 1:26 AM, Sean Christopherson wrote:
> On Mon, Feb 26, 2024, isaku.yamahata@...el.com wrote:
>> +	 */
>> +	struct kvm_vcpu *vcpu = &tdx->vcpu;
>> +
>> +	guest_state_enter_irqoff();
>> +
>> +	/*
>> +	 * TODO: optimization:
>> +	 * - Eliminate copy between args and vcpu->arch.regs.
>> +	 * - copyin/copyout registers only if (tdx->tdvmvall.regs_mask != 0)
>> +	 *   which means TDG.VP.VMCALL.
>> +	 */
>> +	args = (struct tdx_module_args) {
>> +		.rcx = tdx->tdvpr_pa,
>> +#define REG(reg, REG)	.reg = vcpu->arch.regs[VCPU_REGS_ ## REG]
> Organizing tdx_module_args's registers by volatile vs. non-volatile is asinine.
> This code should not need to exist.

Did you suggest to align the tdx_module_args with enum kvm_reg for GP 
registers, so it can be done by a simple mem copy?

>
>> +	WARN_ON_ONCE(!kvm_rebooting &&
>> +		     (tdx->exit_reason.full & TDX_SW_ERROR) == TDX_SW_ERROR);
>> +
>> +	guest_state_exit_irqoff();
>> +}
>> +
>>