From: Mark Brown Date: Tue, 7 Mar 2023 17:37:14 +0000 (+0000) Subject: KVM: arm64: Document check for TIF_FOREIGN_FPSTATE X-Git-Tag: v6.6.7~2639^2~12^2~1^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4c181e3d352e9280c84fb4b4c7a8940ce005374e;p=platform%2Fkernel%2Flinux-starfive.git KVM: arm64: Document check for TIF_FOREIGN_FPSTATE In kvm_arch_vcpu_load_fp() we unconditionally set the current FP state to FP_STATE_HOST_OWNED, this will be overridden to FP_STATE_NONE if TIF_FOREIGN_FPSTATE is set but the check is deferred until kvm_arch_vcpu_ctxflush_fp() where we are no longer preemptable. Add a comment to this effect to help avoid people being concerned about the lack of a check and discover where the check is done. Signed-off-by: Mark Brown Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20221214-kvm-arm64-sme-context-switch-v2-1-57ba0082e9ff@kernel.org --- diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 1279949..3fd0ce6 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -81,6 +81,11 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) fpsimd_kvm_prepare(); + /* + * We will check TIF_FOREIGN_FPSTATE just before entering the + * guest in kvm_arch_vcpu_ctxflush_fp() and override this to + * FP_STATE_FREE if the flag set. + */ vcpu->arch.fp_state = FP_STATE_HOST_OWNED; vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);