This is v3 of this series aiming at simplifying the FP handling. It recently became apparent that we are mapping each vcpu thread's thread_info structure at EL2 for the sole purpose of checking on the TIF_FOREIGN_FPSTATE flag. Given that this looks like a slightly over-engineered way of sharing a single bit of information, let's move to a slightly more obvious implementation by maintaining a vcpu-private shadow flag that represents the same state. In the same vein, it appears that the code that deals with saving the host SVE state when used by the guest can never run, and that's by construction. This is actually a good thing, because it be guaranteed to explode on nVHE. Let's get rid of it. I also take this opportunity to add what looks like a missing, and nonetheless crucial piece of information to the FPSIMD code regarding the way KVM (ab)uses the TIF_FOREIGN_FPSTATE. Lightly tested on an A53 box with a bunch of paranoia instances running in both host and guests, and more heavily on a FVP to check the SVE behaviour (using the sve-test selftest running in both host and guest at the same time). I plan to take this series for a spin in -next immediately. * From v2 [2]: - Removed obsolete comments - Removed __sve_save_state which is now unused * From v1 [1]: - New patch getting rid of the host SVE save code - Reworded the documentation update patch [1] https://lore.kernel.org/r/20211021151124.3098113-1-maz@xxxxxxxxxx [2] https://lore.kernel.org/r/20211028111640.3663631-1-maz@xxxxxxxxxx Marc Zyngier (6): KVM: arm64: Reorder vcpu flag definitions KVM: arm64: Get rid of host SVE tracking/saving KVM: arm64: Remove unused __sve_save_state KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE KVM: arm64: Stop mapping current thread_info at EL2 arm64/fpsimd: Document the use of TIF_FOREIGN_FPSTATE by KVM arch/arm64/include/asm/kvm_host.h | 29 +++++++++--------- arch/arm64/include/asm/kvm_hyp.h | 1 - arch/arm64/kernel/fpsimd.c | 6 +++- arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/fpsimd.c | 40 +++++++++---------------- arch/arm64/kvm/hyp/fpsimd.S | 6 ---- arch/arm64/kvm/hyp/include/hyp/switch.h | 30 +++---------------- arch/arm64/kvm/hyp/nvhe/switch.c | 1 - arch/arm64/kvm/hyp/vhe/switch.c | 1 - 9 files changed, 38 insertions(+), 77 deletions(-) -- 2.30.2
