KVM: PPC: Book3S: Fix server always zero from kvmppc_xive_get_xive()

In KVM's XICS-on-XIVE emulation, kvmppc_xive_get_xive() returns the
value of state->guest_server as "server". However, this value is not
set by it's counterpart kvmppc_xive_set_xive(). When the guest uses
this interface to migrate interrupts away from a CPU that is going
offline, it sees all interrupts as belonging to CPU 0, so they are
left assigned to (now) offline CPUs.

This patch removes the guest_server field from the state, and returns
act_server in it's place (that is, the CPU actually handling the
interrupt, which may differ from the one requested).

Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller")
Cc: stable@vger.kernel.org
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

2 files changed, 2 insertions, 4 deletions

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index 13304622ab1c..bf457843e032 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -622,7 +622,7 @@ int kvmppc_xive_get_xive(struct kvm *kvm, u32 irq, u32 *server,
                 return -EINVAL;
         state = &sb->irq_state[idx];
         arch_spin_lock(&sb->lock);
-        *server = state->guest_server;
+        *server = state->act_server;
         *priority = state->guest_priority;
         arch_spin_unlock(&sb->lock);
 
@@ -1331,7 +1331,7 @@ static int xive_get_source(struct kvmppc_xive *xive, long irq, u64 addr)
         xive->saved_src_count++;
 
         /* Convert saved state into something compatible with xics */
-        val = state->guest_server;
+        val = state->act_server;
         prio = state->saved_scan_prio;
 
         if (prio == MASKED) {
@@ -1507,7 +1507,6 @@ static int xive_set_source(struct kvmppc_xive *xive, long irq, u64 addr)
         /* First convert prio and mark interrupt as untargetted */
         act_prio = xive_prio_from_guest(guest_prio);
         state->act_priority = MASKED;
-        state->guest_server = server;
 
         /*
          * We need to drop the lock due to the mutex below. Hopefully
diff --git a/arch/powerpc/kvm/book3s_xive.h b/arch/powerpc/kvm/book3s_xive.h
index 5938f7644dc1..6ba63f8e8a61 100644
--- a/arch/powerpc/kvm/book3s_xive.h
+++ b/arch/powerpc/kvm/book3s_xive.h
@@ -35,7 +35,6 @@ struct kvmppc_xive_irq_state {
         struct xive_irq_data *pt_data;  /* XIVE Pass-through associated data */
 
         /* Targetting as set by guest */
-        u32 guest_server;               /* Current guest selected target */
         u8 guest_priority;              /* Guest set priority */
         u8 saved_priority;              /* Saved priority when masking */