On Fri, Nov 01, 2024, Oliver Upton wrote: > Hey, > > On Fri, Nov 01, 2024 at 07:48:00AM -0700, Sean Christopherson wrote: > > On Fri, Nov 01, 2024, Mark Brown wrote: > > > On Wed, Oct 09, 2024 at 08:49:42AM -0700, Sean Christopherson wrote: > > > > Return a uint64_t from vcpu_get_reg() instead of having the caller provide > > > > a pointer to storage, as none of the vcpu_get_reg() usage in KVM selftests > > > > accesses a register larger than 64 bits, and vcpu_set_reg() only accepts a > > > > 64-bit value. If a use case comes along that needs to get a register that > > > > is larger than 64 bits, then a utility can be added to assert success and > > > > take a void pointer, but until then, forcing an out param yields ugly code > > > > and prevents feeding the output of vcpu_get_reg() into vcpu_set_reg(). > > > > > > This commit, which is in today's -next as 5c6c7b71a45c9c, breaks the > > > build on arm64: > > > > > > aarch64/psci_test.c: In function ‘host_test_system_off2’: > > > aarch64/psci_test.c:247:9: error: too many arguments to function ‘vcpu_get_reg’ > > > 247 | vcpu_get_reg(target, KVM_REG_ARM_PSCI_VERSION, &psci_version); > > > | ^~~~~~~~~~~~ > > > In file included from aarch64/psci_test.c:18: > > > include/kvm_util.h:705:24: note: declared here > > > 705 | static inline uint64_t vcpu_get_reg(struct kvm_vcpu *vcpu, uint64_t id) > > > | ^~~~~~~~~~~~ > > > At top level: > > > cc1: note: unrecognized command-line option ‘-Wno-gnu-variable-sized-type-not-at > > > -end’ may have been intended to silence earlier diagnostics > > > > > > since the updates done to that file did not take account of 72be5aa6be4 > > > ("KVM: selftests: Add test for PSCI SYSTEM_OFF2") which has been merged > > > in the kvm-arm64 tree. > > > > Bugger. In hindsight, it's obvious that of course arch selftests would add usage > > of vcpu_get_reg(). > > > > Unless someone has a better idea, I'll drop the series from kvm-x86, post a new > > version that applies on linux-next, and then re-apply the series just before the > > v6.13 merge window (rinse and repeat as needed if more vcpu_get_reg() users come > > along). > > Can you instead just push out a topic branch and let the affected > maintainers deal with it? This is the usual way we handle conflicts > between trees... That'd work too, but as you note below, doing that now throws a wrench in things because essentially all arch maintainers would need merge that topic branch, otherwise linux-next would end up in the same state. > > That would be a good oppurtunity to do the $(ARCH) directory switch[*] too, e.g. > > have a "selftests_late" or whatever topic branch. > > The right time to do KVM-wide changes (even selftests) is *early* in the > development cycle, not last minute. It gives us plenty of time to iron out > the wrinkles. Yeah, that was the original plan, then the stupid strict aliasing bug happened, and I honestly forgot the vcpu_get_reg() changes would need to be consumed by other architectures. Other than letting me forget about this mess a few weeks earlier, there's no good reason to force this into 6.13. So, I'll drop the series from 6.13, post new versions of the this and the $(ARCH) series just before the merge window, and then either send a pull request to Paolo for 6.14 as soon as the 6.13 merge window closes, or ask/bribe Paolo to apply everything directly.