This series fully models the behaviour of WFxT instructions. We already had support for WFE for M-profile but we left off A-profile as it has more potential sources of wake-ups. The main one is the event stream which includes events from significant bits of the timer ticking over.
The refactoring from the previous iterations of the patch have now been merged. I've dropped trying to fully model the global monitor in favour of taking advantage of the architectural flexibility to have an IMPDEF event wake up for any reason. We treat the setting of exclusive_addr as such a reason because it indicates the current vCPU is in a ldstx exclusive region and we don't want the guest to deadlock. This does mean the system won't sleep on WFE enabled locks but people shouldn't be relying on QEMU to model real world sleep patterns anyway given the efficiency of emulation compared to real HW. I've written a test case using kvm-unit-tests: Message-ID: <[email protected]> Date: Wed, 27 May 2026 12:18:21 +0100 Subject: [kvm-unit-tests PATCH v2] arm: add wfx test case From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <[email protected]> v8 - Fixed quanta-gsj model SEV errata failure - Update the aspeed_anacapa test case - Ensure wake up events for V6K/V7 and plain V8 - merged trap with implementation v7 - more r-b's - extended comment for typo fix v6 - add typo fix - addressed rth's comments v5 - addressed rth's comments - all but one patch now reviewed v4 - precursor refactor patches now merged - dropped global monitor emulation - addressed other comments - tested with check-tcg and kvm-unit-test wfx tests v3 - fixed the WFE exception handling v2 - I've kept the tests separate, see: Message-ID: <[email protected]> Date: Fri, 17 Apr 2026 17:43:20 +0100 Subject: [PATCH 0/7] tests/tcg: more capabilities for aarch64-softmmu tests From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <[email protected]> - tweaks to global monitor behaviour - STLR/STL will also trigger events to avoid deadlocks - see under the --- in the patches for details Alex. Alex Bennée (7): hw/arm: use cortex-a9 mpcore base for CBAR on npcm7xx machines tests/functional: update anacapa-bmc image target/arm: do not clear halting reason in has_work helper target/arm: ensure we create the wxft_timer for all modes target/arm: implements SEV/SEVL for all modes target/arm: enable WFE sleeping for A-profile target/arm: implement WFET include/hw/core/sysemu-cpu-ops.h | 3 + target/arm/cpu.h | 2 +- target/arm/tcg/helper-defs.h | 3 +- target/arm/tcg/translate.h | 18 ++ target/arm/tcg/a32.decode | 5 +- target/arm/tcg/a64.decode | 5 +- target/arm/tcg/t16.decode | 4 +- target/arm/tcg/t32.decode | 4 +- hw/arm/npcm7xx.c | 2 +- target/arm/cpu.c | 26 +- target/arm/tcg/op_helper.c | 252 ++++++++++++++++++-- target/arm/tcg/translate-a64.c | 42 ++-- target/arm/tcg/translate.c | 34 +-- tests/functional/arm/test_aspeed_anacapa.py | 4 +- 14 files changed, 331 insertions(+), 73 deletions(-) -- 2.47.3
