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. 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. Marc Zyngier (4): KVM: arm64: Reorder vcpu flag definitions 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 | 28 ++++++++++++------------- arch/arm64/kernel/fpsimd.c | 5 ++++- arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/fpsimd.c | 20 ++++++++---------- arch/arm64/kvm/hyp/include/hyp/switch.h | 3 +-- arch/arm64/kvm/hyp/nvhe/switch.c | 1 - arch/arm64/kvm/hyp/vhe/switch.c | 1 - 7 files changed, 29 insertions(+), 30 deletions(-) -- 2.30.2
