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.