powerpc/xive: Fix trying to "push" an already active pool VP

commit b32e56e5a87a1f9243db92bc7a5df0ffb4627cfb upstream.

When setting up a CPU, we "push" (activate) a pool VP for it.

However it's an error to do so if it already has an active
pool VP.

This happens when doing soft CPU hotplug on powernv since we
don't tear down the CPU on unplug. The HW flags the error which
gets captured by the diagnostics.

Fix this by making sure to "pull" out any already active pool
first.

Fixes: 243e25112d06 ("powerpc/xive: Native exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index ebc244b08d6748512c19199446d25f7ac49fca9b..0f89ee557b044f66435b2e145c58fa4e7076e0d4 100644 (file)
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c
@@ -388,6 +388,10 @@ static void xive_native_setup_cpu(unsigned int cpu, struct xive_cpu *xc)
        if (xive_pool_vps == XIVE_INVALID_VP)
                return;
 
+       /* Check if pool VP already active, if it is, pull it */
+       if (in_be32(xive_tima + TM_QW2_HV_POOL + TM_WORD2) & TM_QW2W2_VP)
+               in_be64(xive_tima + TM_SPC_PULL_POOL_CTX);
+
        /* Enable the pool VP */
        vp = xive_pool_vps + cpu;
        pr_debug("CPU %d setting up pool VP 0x%x\n", cpu, vp);