linux-kernel - Re: [PATCH v13 003/113] KVM: TDX: Initialize the TDX module when loading the KVM intel kernel module

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Date:   Wed, 15 Mar 2023 10:35:20 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>
CC:     "Christopherson,, Sean" <seanjc@...gle.com>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Aktas, Erdem" <erdemaktas@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "zhi.wang.linux@...il.com" <zhi.wang.linux@...il.com>,
        "dmatlack@...gle.com" <dmatlack@...gle.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>
Subject: Re: [PATCH v13 003/113] KVM: TDX: Initialize the TDX module when
 loading the KVM intel kernel module

> 
> > +static bool enable_tdx __ro_after_init;
> > +module_param_named(tdx, enable_tdx, bool, 0444);
> > +
> > +static __init int vt_hardware_setup(void)
> > +{
> > +	int ret;
> > +
> > +	ret = vmx_hardware_setup();
> > +	if (ret)
> > +		return ret;
> > +
> > +	enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
> 
> Unfortunately, the enable_tdx should also be protected by the
> cpus_read_lock(),
> because CPU hotplug code path checks it too (as seen in your next patch).

Sorry I was wrong.  I forgot the CPU hotplug callbacks are registered in
kvm_init(), which happens after hardware_setup(), so the CPU hotplug code cannot
race with this hardware_setup() code here.

[...]

> 
> I think you can merge next patch with this one because they are kinda related.
>  
> 
> Putting them together allows people to review more easily.

And perhaps this isn't necessary either.