Legal definition of genocide from the UN Convention on the Prevention and Punishment of the Crime of Genocide is:
any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such: killing members of the group; causing serious bodily or mental harm to members of the group; deliberately inflicting on the group conditions of life, calculated to bring about its physical destruction in whole or in part; imposing measures intended to prevent births within the group; [and] forcibly transferring children of the group to another group
Since Soviets goal was to eliminate the Polish officers corps and the intelligentsia, I think it does qualify as a genocide.
I know this because there were members of my family in the intelligencia in Poland in the 1940s. Those who stood up to the Soviets were persecuted, those who stayed out of politics weren't.
As to the officer corps, it does not constitute an ethnic, racial, or religious group. So yes, the Soviets tried to eliminate the Polish officer corps, but this does not constitute a genocide.
Let me just make perfectly clear, I'm in no way defending the Soviets. They were some of the worst people in the history of the world. They were, IMHO, worse than the Nazis since they murdered orders of magnitude more people. However, I do think we need to keep the facts straight, and that is all that I'm doing here. The fact is the Soviets did not perpetrate a genocide in Poland, though what they did was morally just as bad, IMHO.
On the other hand, I think what they did in the Ukraine could be classified as an attempted genocide.