From 23afc82539cfcce105bf18c5c835c75e463ca349 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Mon, 24 Jan 2022 15:57:19 +0000 Subject: [PATCH] KVM: arm64: Add comments for context flush and sync callbacks Add a little bit of information on where _ctxflush_fp() and _ctxsync_fp() are called to help people unfamiliar with the code get up to speed. Signed-off-by: Mark Brown Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220124155720.3943374-2-broonie@kernel.org --- arch/arm64/kvm/fpsimd.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 2f48fd3..397fdac7 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -84,6 +84,11 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED; } +/* + * Called just before entering the guest once we are no longer + * preemptable. Syncs the host's TIF_FOREIGN_FPSTATE with the KVM + * mirror of the flag used by the hypervisor. + */ void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu) { if (test_thread_flag(TIF_FOREIGN_FPSTATE)) @@ -93,10 +98,11 @@ void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu) } /* - * If the guest FPSIMD state was loaded, update the host's context - * tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu - * so that they will be written back if the kernel clobbers them due to - * kernel-mode NEON before re-entry into the guest. + * Called just after exiting the guest. If the guest FPSIMD state + * was loaded, update the host's context tracking data mark the CPU + * FPSIMD regs as dirty and belonging to vcpu so that they will be + * written back if the kernel clobbers them due to kernel-mode NEON + * before re-entry into the guest. */ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) { -- 2.7.4