linux-kernel - Re: [PATCH v19 109/130] KVM: TDX: Handle TDX PV port io hypercall

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Message-ID: <20240417201058.GL3039520@ls.amr.corp.intel.com>
Date: Wed, 17 Apr 2024 13:10:58 -0700
From: Isaku Yamahata <isaku.yamahata@...el.com>
To: Binbin Wu <binbin.wu@...ux.intel.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,
	Sean Christopherson <seanjc@...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,
	isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v19 109/130] KVM: TDX: Handle TDX PV port io hypercall

On Wed, Apr 17, 2024 at 08:51:39PM +0800,
Binbin Wu <binbin.wu@...ux.intel.com> wrote:

> 
> 
> On 2/26/2024 4:26 PM, isaku.yamahata@...el.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > 
> > Wire up TDX PV port IO hypercall to the KVM backend function.
> > 
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> > Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
> > ---
> > v18:
> > - Fix out case to set R10 and R11 correctly when user space handled port
> >    out.
> > ---
> >   arch/x86/kvm/vmx/tdx.c | 67 ++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 67 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index a2caf2ae838c..55fc6cc6c816 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -1152,6 +1152,71 @@ static int tdx_emulate_hlt(struct kvm_vcpu *vcpu)
> >   	return kvm_emulate_halt_noskip(vcpu);
> >   }
> > +static int tdx_complete_pio_out(struct kvm_vcpu *vcpu)
> > +{
> > +	tdvmcall_set_return_code(vcpu, TDVMCALL_SUCCESS);
> > +	tdvmcall_set_return_val(vcpu, 0);
> > +	return 1;
> > +}
> > +
> > +static int tdx_complete_pio_in(struct kvm_vcpu *vcpu)
> > +{
> > +	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
> > +	unsigned long val = 0;
> > +	int ret;
> > +
> > +	WARN_ON_ONCE(vcpu->arch.pio.count != 1);
> > +
> > +	ret = ctxt->ops->pio_in_emulated(ctxt, vcpu->arch.pio.size,
> > +					 vcpu->arch.pio.port, &val, 1);
> > +	WARN_ON_ONCE(!ret);
> > +
> > +	tdvmcall_set_return_code(vcpu, TDVMCALL_SUCCESS);
> > +	tdvmcall_set_return_val(vcpu, val);
> > +
> > +	return 1;
> > +}
> > +
> > +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);
> > +	port = tdvmcall_a2_read(vcpu);
> > +
> > +	if (size != 1 && size != 2 && size != 4) {
> > +		tdvmcall_set_return_code(vcpu, TDVMCALL_INVALID_OPERAND);
> > +		return 1;
> > +	}
> > +
> > +	if (write) {
> > +		val = tdvmcall_a3_read(vcpu);
> > +		ret = ctxt->ops->pio_out_emulated(ctxt, size, port, &val, 1);
> > +
> > +		/* No need for a complete_userspace_io callback. */
> I am confused about the comment.
> 
> The code below sets the complete_userspace_io callback for write case,
> i.e. tdx_complete_pio_out().

You're correct. This comment is stale and should be removed it.
-- 
Isaku Yamahata <isaku.yamahata@...el.com>