[kernel] E: Add XapicOnly interrupt mode (skip PIC init on microvm)#14
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[kernel] E: Add XapicOnly interrupt mode (skip PIC init on microvm)#14esaurez wants to merge 1 commit into
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Add XapicOnly interrupt controller variant for WHP+microvm that skips legacy 8259 PIC initialization entirely. When the xAPIC timer has been successfully initialized via try_init_xapic_timer(), the WHP LAPIC emulator handles timer delivery and EOI via MMIO without VM exits. PIC I/O ports (0x20/0x21/0xA0/0xA1) are never accessed, eliminating ~47 VM exits per cold-start. Changes: - New XapicOnly(Xapic) variant in InterruptControllerType enum - Early-return in InterruptController::new() when eoi_xapic is Some under cfg(feature = "microvm", target_arch = "x86") - ack(): delegates to xapic.ack() - unmask(): no-op (LAPIC timer already unmasked during calibration) - start_core(): returns OperationNotSupported (microvm is single-core) - set_handler/get_handler: identity mapping (no IOAPIC routing) Benchmark (20 iterations, high-perf power mode, p50): Config total guest_exec exit_handling baseline (dev) 60,483us 46,238us 7,208us + XapicOnly TBD TBD TBD Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Replica of nanvix#1982.
Add XapicOnly interrupt controller variant for WHP+microvm that skips legacy 8259 PIC initialization entirely, eliminating ~47 VM exits per cold-start.
New XapicOnly(Xapic) variant in InterruptControllerType enum with dispatch logic for ack(), unmask(), start_core(), set_handler/get_handler.
Activation condition: cfg(feature = microvm, target_arch = x86) AND eoi_xapic is Some.
Benchmark (50 iterations, high-perf tuned, p50)