1 files changed, 28 insertions, 8 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rm_xics.c b/arch/powerpc/kvm/book3s_hv_rm_xics.c
index 3ee38e6e884f..7b066f6b02ad 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_xics.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_xics.c
@@ -183,8 +183,10 @@ static void icp_rm_down_cppr(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
          * state update in HW (ie bus transactions) so we can handle them
          * separately here as well.
          */
-        if (resend)
+        if (resend) {
                 icp->rm_action |= XICS_RM_CHECK_RESEND;
+                icp->rm_resend_icp = icp;
+        }
 }
 
 
@@ -254,10 +256,25 @@ int kvmppc_rm_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
          * nothing needs to be done as there can be no XISR to
          * reject.
          *
+         * ICP state: Check_IPI
+         *
          * If the CPPR is less favored, then we might be replacing
-         * an interrupt, and thus need to possibly reject it as in
+         * an interrupt, and thus need to possibly reject it.
          *
-         * ICP state: Check_IPI
+         * ICP State: IPI
+         *
+         * Besides rejecting any pending interrupts, we also
+         * update XISR and pending_pri to mark IPI as pending.
+         *
+         * PAPR does not describe this state, but if the MFRR is being
+         * made less favored than its earlier value, there might be
+         * a previously-rejected interrupt needing to be resent.
+         * Ideally, we would want to resend only if
+         *      prio(pending_interrupt) < mfrr &&
+         *      prio(pending_interrupt) < cppr
+         * where pending interrupt is the one that was rejected. But
+         * we don't have that state, so we simply trigger a resend
+         * whenever the MFRR is made less favored.
          */
         do {
                 old_state = new_state = ACCESS_ONCE(icp->state);
@@ -270,13 +287,14 @@ int kvmppc_rm_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
                 resend = false;
                 if (mfrr < new_state.cppr) {
                         /* Reject a pending interrupt if not an IPI */
-                        if (mfrr <= new_state.pending_pri)
+                        if (mfrr <= new_state.pending_pri) {
                                 reject = new_state.xisr;
-                        new_state.pending_pri = mfrr;
-                        new_state.xisr = XICS_IPI;
+                                new_state.pending_pri = mfrr;
+                                new_state.xisr = XICS_IPI;
+                        }
                 }
 
-                if (mfrr > old_state.mfrr && mfrr > new_state.cppr) {
+                if (mfrr > old_state.mfrr) {
                         resend = new_state.need_resend;
                         new_state.need_resend = 0;
                 }
@@ -289,8 +307,10 @@ int kvmppc_rm_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
         }
 
         /* Pass resends to virtual mode */
-        if (resend)
+        if (resend) {
                 this_icp->rm_action |= XICS_RM_CHECK_RESEND;
+                this_icp->rm_resend_icp = icp;
+        }
 
         return check_too_hard(xics, this_icp);
 }