On Wed, Feb 12, 2025 at 12:07:45AM +0000, Vishal Annapurve wrote:
> Direct HLT instruction execution causes #VEs for TDX VMs which is routed
> to hypervisor via TDCALL. safe_halt() routines execute HLT in STI-shadow
> so IRQs need to remain disabled until the TDCALL to ensure that pending
> IRQs are correctly treated as wake events. So "sti;hlt" sequence needs to
> be replaced with "TDCALL; raw_local_irq_enable()" for TDX VMs.
The last sentence is somewhat confusing.
Maybe drop it and add explanation that #VE handler doesn't have info about
STI shadow, enables interrupts before TDCALL which can lead to missed
wakeup events.
> @@ -409,6 +410,12 @@ void __cpuidle tdx_safe_halt(void)
> WARN_ONCE(1, "HLT instruction emulation failed\n");
> }
>
> +static void __cpuidle tdx_safe_halt(void)
> +{
> + tdx_halt();
> + raw_local_irq_enable();
What is justification for raw_? Why local_irq_enable() is not enough?
To very least, it has to be explained.
--
Kiryl Shutsemau / Kirill A. Shutemov
