linux-kernel - Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on demand

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Message-ID: <20230630184229.GG3436214@ls.amr.corp.intel.com>
Date:   Fri, 30 Jun 2023 11:42:29 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     "Huang, Kai" <kai.huang@...el.com>
Cc:     "peterz@...radead.org" <peterz@...radead.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
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        "pbonzini@...hat.com" <pbonzini@...hat.com>,
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        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
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        "Williams, Dan J" <dan.j.williams@...el.com>,
        isaku.yamahata@...il.com
Subject: Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on
 demand

On Fri, Jun 30, 2023 at 10:09:08AM +0000,
"Huang, Kai" <kai.huang@...el.com> wrote:

> On Fri, 2023-06-30 at 11:22 +0200, Peter Zijlstra wrote:
> > On Thu, Jun 29, 2023 at 12:15:13AM +0000, Huang, Kai wrote:
> > 
> > > > 	Can be called locally or through an IPI function call.
> > > > 
> > > 
> > > Thanks.  As in another reply, if using spinlock is OK, then I think we can say
> > > it will be called either locally or through an IPI function call.  Otherwise, we
> > > do via a new separate function tdx_global_init() and no lock is needed in that
> > > function.  The caller should call it properly.
> > 
> > IPI must use raw_spinlock_t. I'm ok with using raw_spinlock_t if there's
> > actual need for that, but the code as presented didn't -- in comments or
> > otherwise -- make it clear why it was as it was.
> 
> There's no hard requirement as I replied in another email.
> 
> Presumably you prefer the option to have a dedicated tdx_global_init() so we can
> avoid the raw_spinlock_t?

TDX KVM calls tdx_cpu_enable() in IPI context as KVM hardware_setup() callback.
tdx_cpu_enable() calls tdx_global_init().
-- 
Isaku Yamahata <isaku.yamahata@...il.com>