Warm the chicken broth and rosemary in a saucepan over medium heat; set aside. Heat 1 tablespoon olive oil in a large Dutch oven or pot over medium-high heat. Add the pancetta and cook until crisp, 4 to 5 minutes; remove to a plate with a slotted spoon. Add the mushrooms to the pot and cook until slightly browned, 3 to 4 minutes. Remove to the plate; set aside.
Add the remaining 1 tablespoon olive oil to the pot; add the onion and cook until softened, about 4 minutes. Add the rice and toast, stirring, 2 to 3 minutes. Stir in the wine and cook, scraping up any browned bits, until the wine is absorbed, 3 to 5 minutes.
Add 3 cups warm broth and bring to a simmer. Cook, stirring, until most of the liquid is absorbed, 8 to 10 minutes. Add 3 more cups broth; return to a simmer and cook, stirring, until the rice is just tender, about 13 minutes.
Remove the pot from the heat; stir in the pancetta, mushrooms, butter, cheese and chives. Stir in more hot broth if the risotto is too thick; season with salt and pepper. Top with more chives.