linux-kernel - Re: [RFC v2-fix-v1 3/3] x86/tdx: Handle port I/O

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Message-ID: <CAPcyv4hBiDNOQ-2b5zxaUUyHo9k2h5UOQvM_wGtw_XTok-BmAQ@mail.gmail.com>
Date:   Mon, 7 Jun 2021 15:00:42 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v2-fix-v1 3/3] x86/tdx: Handle port I/O

On Mon, Jun 7, 2021 at 2:52 PM Kuppuswamy, Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
>
>
>
> On 6/7/21 10:17 AM, Dan Williams wrote:
> >> Did it answer your query?
> > Yes, all but the concern of printk recursion.
>
> I think recursion is not possible because printk will
> handle it (using console_lock). If another print is
> triggered during the current printk handling, it will
> be directed to logbuf and delayed.
>
> https://elixir.bootlin.com/linux/latest/source/kernel/printk/printk_safe.c#L382

That depends on printk_nmi_direct_enter() to set the context, wouldn't
an equivalent printk_ve_direct_enter() context flag be needed as well?