From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: 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 05:20:52 +0300 [thread overview]
Message-ID: <20220520022052.mkrc4v4evtp74bxe@black.fi.intel.com> (raw)
In-Reply-To: <20220519220349.GM2578@worktop.programming.kicks-ass.net>
On Fri, May 20, 2022 at 12:03:49AM +0200, Peter Zijlstra wrote:
>
> On Thu, May 19, 2022 at 11:27:59PM +0200, Peter Zijlstra wrote:
> > --- a/arch/x86/coco/tdx/tdx.c
> > +++ b/arch/x86/coco/tdx/tdx.c
> > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void)
> > */
> > if (__halt(irq_disabled, do_sti))
> > WARN_ONCE(1, "HLT instruction emulation failed\n");
> > +
> > + /* XXX I can't make sense of what @do_sti actually does */
> > + raw_local_irq_disable();
> > }
> >
>
> Kirill, Dave says I should prod you :-)
It calls STI just before doing TDCALL that requests HLT.
See comment above $TDX_HCALL_ISSUE_STI usage in __tdx_hypercall()[1].
__halt(do_sti == true) matches native_safe_halt() semantics (or suppose
to) and __halt(do_sti == false) corresponds to native_halt().
For context, see Section 3.8 in GHCI[2]
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/tree/arch/x86/coco/tdx/tdcall.S?h=x86/tdx#n151
[2] https://www.intel.com/content/dam/develop/external/us/en/documents/intel-tdx-guest-hypervisor-communication-interface-1.0-344426-002.pdf
--
Kirill A. Shutemov
next prev parent reply other threads:[~2022-05-20 2:21 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 [this message]
2022-05-20 7:06 ` Peter Zijlstra
2022-05-20 10:13 ` Kirill A. Shutemov
2022-05-20 12:58 ` Peter Zijlstra
2022-05-24 14:55 ` Isaku Yamahata
2022-05-23 10:02 ` Gautham R. Shenoy
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