When this was introduced, kvm_flush_remote_tlbs() could be called without holding mmu_lock. It is now acknowledged that the function must be called before releasing mmu_lock, and all callers have already been changed to do so.
This patch adds a comment explaining this. Signed-off-by: Takuya Yoshikawa <[email protected]> --- virt/kvm/kvm_main.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a9e999a..53521ea 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -184,6 +184,15 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) return called; } +/* + * tlbs_dirty is used only for optimizing x86's shadow paging code with mmu + * notifiers in mind, see the note on sync_page(). Since it is always protected + * with mmu_lock there, should kvm_flush_remote_tlbs() be called before + * releasing mmu_lock, the trick using smp_mb() and cmpxchg() is not necessary. + * + * Currently, the assumption about kvm_flush_remote_tlbs() callers is true, but + * the code is kept as is for someone who may change the rule in the future. + */ void kvm_flush_remote_tlbs(struct kvm *kvm) { long dirty_count = kvm->tlbs_dirty; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
