What was Homer's attitude or perspective concerning war itself?
I think that a bit more detail and specificity in the question is needed. In Homer's Iliad, I don't see much in way of positivity about war. Homer goes out of his way to debunk the Classical myth regarding the perceived glory and joy of war. Rather, Homer shows war to be what it is: Cruel, savage, and filled with heartache for those who are cursed to survive. Hector is a great example of this. Though he is a warrior filled with a sense of arete and skill, he is filled with the pain of leaving his family, making his wife a widow and his son fatherless. We see this when he has to face Achilles, and the fear that grips a great warrior. Homer's construction of Achilles is one of intense power, but one where there is mourning when his best friend, Patrocles, is killed as well as a sense of agony about his deeds when Priam comes to beg for his son. The sacking of Troy is not a moment where there is glory and triumph, as much as savagery and intensity of pain, as demonstrated with the killing of Hector's son. Homer is smart enough to be able to show how the only real fruit of war is a legacy of suffering and pain for the survivors, making the dead its only benefactors.