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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
Date: Fri, 20 May 2022 14:58:19 +0200	[thread overview]
Message-ID: <20220520125819.GS2578@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220520101322.flxf52mg6vkkbc7r@box.shutemov.name>

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.

  reply	other threads:[~2022-05-20 12:58 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-19 21:27 [RFC][PATCH 0/9] Rework cpuidle vs instrumentation Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 1/9] x86/perf/amd: Remove tracing from perf_lopwr_cb() Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 2/9] x86/idle: Replace x86_idle with a static_call Peter Zijlstra
2022-05-30 11:07   ` Frederic Weisbecker
2022-05-19 21:27 ` [RFC][PATCH 3/9] cpuidle: Move IRQ state validation Peter Zijlstra
2022-05-30 11:36   ` Frederic Weisbecker
2022-05-30 12:00     ` Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 4/9] idle: Fix rcu_idle_*() usage Peter Zijlstra
2022-05-23  9:46   ` Gautham R. Shenoy
2022-05-31  9:33     ` Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 5/9] rcu: Fix rcu_idle_exit() Peter Zijlstra
2022-05-20 21:00   ` Paul E. McKenney
2022-05-19 21:27 ` [RFC][PATCH 6/9] acpi_idle: Remove tracing Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 7/9] cpuidle: Annotate poll_idle() Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 8/9] objtool/idle: Validate __cpuidle code as noinstr Peter Zijlstra
2022-05-19 21:27 ` [RFC][PATCH 9/9] arch/idle: Change arch_cpu_idle() IRQ behaviour Peter Zijlstra
2022-05-19 22:03   ` Peter Zijlstra
2022-05-20  2:20     ` Kirill A. Shutemov
2022-05-20  7:06       ` Peter Zijlstra
2022-05-20 10:13         ` Kirill A. Shutemov
2022-05-20 12:58           ` Peter Zijlstra [this message]
2022-05-24 14:55             ` Isaku Yamahata
2022-05-23 10:02   ` Gautham R. Shenoy

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