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Date:   Fri, 20 May 2022 14:58:19 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     Isaku Yamahata <isaku.yamahata@intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        frederic@kernel.org, paulmck@kernel.org, rjw@rjwysocki.net,
        x86@kernel.org, linux-kernel@vger.kernel.org, jpoimboe@kernel.org
Subject: Re: [RFC][PATCH 9/9] arch/idle: Change arch_cpu_idle() IRQ behaviour
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On Fri, May 20, 2022 at 01:13:22PM +0300, Kirill A. Shutemov wrote:

> So you want to call call the HLT hypercall with .irq_disabled=false and
> .do_sti=false, but actual RFLAGS.IF in the guest is 0 and avoid CLI on
> wake up expecting it to be cleared already, right?

Yep, just like MWAIT can, avoids pointless IF flipping.

> My reading of the spec is "don't do that". But actual behaviour is up to
> VMM and TDX module implementation. VMM doens't have access to the guest
> register file, so it *may* work, I donno.

Yeah, it totally *can* work, but I've no idea if they done the right
thing.