I'm pretty sure you don't think that qualia are reified in the brain-- that a surgeon could go in with tongs and pull out a little lump of qualia

I do think that qualia are reified in the brain. I do not think that a surgeon could go in with tongs and remove them any more than he could in with tongs and remove your recognition of your grandmother.

If qualia and other mental phenomena are not computational, then what are they?

They're a physical effect caused by the operation of a brain, just as gravity is a physical effect of mass and temperature is a physical effect of Brownian motion. See here and here for one reason why I think the computational view falls somewhere in between problematic and not-even-wrong, inclusive.

ETA: The "grandmother cell" might have been a poorly chosen counterexample, since apparently there's some research that sort of actually supports that notion with respect to face recognition. I learned the phrase as identifying a fallacy. Feel free to mentally substitute some other complex idea that is clearly not embodied in any discrete piece of the brain.