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 for TDX VMs with TDCALL execution followed by enabling of interrupts.
Changes introduced by the series include: - Move *halt() variants outside CONFIG_PARAVIRT_XXL and under CONFIG_PARAVIRT [1]. - Route "sti; hlt" sequences via tdx_safe_halt() for reliability. - Route "hlt" sequences via tdx_halt() to avoid unnecessary #VEs. - Add explicit dependency on CONFIG_PARAVIRT for TDX VMs. - Warn and fail emulation if HLT #VE emulation executes with interrupts enabled. - Clean up TDX specific idle routine override. Changes since v4: 1) Addressed Kirill's comments. v4: https://lore.kernel.org/lkml/20250212000747.3403836-1-vannapu...@google.com/ Changes since v3: 1) Addressed comments from Sean. 2) Included [1] in the series to fix the scenarios where CONFIG_PARAVIRT_XXL could be disabled. v3: https://lore.kernel.org/all/20250206222714.1079059-1-vannapu...@google.com/ [1] https://lore.kernel.org/lkml/20210517235008.257241-1-sathyanarayanan.kuppusw...@linux.intel.com/ Kirill A. Shutemov (1): x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT Vishal Annapurve (3): x86/tdx: Route safe halt execution via tdx_safe_halt() x86/tdx: Emit warning if IRQs are enabled during HLT #VE handling x86/tdx: Remove TDX specific idle routine arch/x86/Kconfig | 1 + arch/x86/coco/tdx/tdx.c | 30 +++++++++++++++++++- arch/x86/include/asm/irqflags.h | 40 +++++++++++++++------------ arch/x86/include/asm/paravirt.h | 20 +++++++------- arch/x86/include/asm/paravirt_types.h | 3 +- arch/x86/include/asm/tdx.h | 2 -- arch/x86/kernel/paravirt.c | 14 ++++++---- arch/x86/kernel/process.c | 3 -- 8 files changed, 71 insertions(+), 42 deletions(-) -- 2.48.1.601.g30ceb7b040-goog
