[PATCH v4 11/14] pnv/xive: Add special handling for pool targets

[Michael Kowal]

From: Glenn Miles <milesg@linux.vnet.ibm.com>

Hypervisor "pool" targets do not get their own interrupt line and instead
must share an interrupt line with the hypervisor "physical" targets.
This also means that the pool ring must use some of the registers from the
physical ring in the TIMA.  Specifically, the NSR, PIPR and CPPR registers:

  NSR = Notification Source Register
  PIPR = Post Interrupt Priority Register
  CPPR = Current Processor Priority Register

The NSR specifies that there is an active interrupt.  The CPPR
specifies the priority of the context and the PIPR specifies the
priority of the interrupt.  For an interrupt to be presented to
a context, the priority of the interrupt must be higher than the
priority of the context it is interrupting (value must be lower).

The existing code was not aware of the sharing of these registers.
This commit adds that support.

Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
---
 hw/intc/xive.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index 9d85da0999..5c5c3a2dd6 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -74,33 +74,49 @@ static uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t 
ring)
 
     if (regs[TM_NSR] & mask) {
         uint8_t cppr = regs[TM_PIPR];
+        uint8_t alt_ring;
+        uint8_t *alt_regs;
+
+        /* POOL interrupt uses IPB in QW2, POOL ring */
+        if ((ring == TM_QW3_HV_PHYS) && (nsr & (TM_QW3_NSR_HE_POOL << 6))) {
+            alt_ring = TM_QW2_HV_POOL;
+        } else {
+            alt_ring = ring;
+        }
+        alt_regs = &tctx->regs[alt_ring];
 
         regs[TM_CPPR] = cppr;
 
         /* Reset the pending buffer bit */
-        regs[TM_IPB] &= ~xive_priority_to_ipb(cppr);
-        regs[TM_PIPR] = ipb_to_pipr(regs[TM_IPB]);
+        alt_regs[TM_IPB] &= ~xive_priority_to_ipb(cppr);
+        regs[TM_PIPR] = ipb_to_pipr(alt_regs[TM_IPB]);
 
         /* Drop Exception bit */
         regs[TM_NSR] &= ~mask;
 
-        trace_xive_tctx_accept(tctx->cs->cpu_index, ring,
-                               regs[TM_IPB], regs[TM_PIPR],
+        trace_xive_tctx_accept(tctx->cs->cpu_index, alt_ring,
+                               alt_regs[TM_IPB], regs[TM_PIPR],
                                regs[TM_CPPR], regs[TM_NSR]);
     }
 
-    return (nsr << 8) | regs[TM_CPPR];
+    return ((uint64_t)nsr << 8) | regs[TM_CPPR];
 }
 
 static void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring)
 {
+    /* HV_POOL ring uses HV_PHYS NSR, CPPR and PIPR registers */
+    uint8_t alt_ring = (ring == TM_QW2_HV_POOL) ? TM_QW3_HV_PHYS : ring;
+    uint8_t *alt_regs = &tctx->regs[alt_ring];
     uint8_t *regs = &tctx->regs[ring];
 
-    if (regs[TM_PIPR] < regs[TM_CPPR]) {
+    if (alt_regs[TM_PIPR] < alt_regs[TM_CPPR]) {
         switch (ring) {
         case TM_QW1_OS:
             regs[TM_NSR] |= TM_QW1_NSR_EO;
             break;
+        case TM_QW2_HV_POOL:
+            alt_regs[TM_NSR] = (TM_QW3_NSR_HE_POOL << 6);
+            break;
         case TM_QW3_HV_PHYS:
             regs[TM_NSR] |= (TM_QW3_NSR_HE_PHYS << 6);
             break;
@@ -108,8 +124,8 @@ static void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring)
             g_assert_not_reached();
         }
         trace_xive_tctx_notify(tctx->cs->cpu_index, ring,
-                               regs[TM_IPB], regs[TM_PIPR],
-                               regs[TM_CPPR], regs[TM_NSR]);
+                               regs[TM_IPB], alt_regs[TM_PIPR],
+                               alt_regs[TM_CPPR], alt_regs[TM_NSR]);
         qemu_irq_raise(xive_tctx_output(tctx, ring));
     }
 }
@@ -217,14 +233,14 @@ static uint64_t xive_tm_vt_poll(XivePresenter *xptr, 
XiveTCTX *tctx,
 static const uint8_t xive_tm_hw_view[] = {
     3, 0, 0, 0,   0, 0, 0, 0,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-0 User */
     3, 3, 3, 3,   3, 3, 0, 2,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-1 OS   */
-    0, 0, 3, 3,   0, 0, 0, 0,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-2 POOL */
+    0, 0, 3, 3,   0, 3, 3, 0,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-2 POOL */
     3, 3, 3, 3,   0, 3, 0, 2,   3, 0, 0, 3,   3, 3, 3, 0, /* QW-3 PHYS */
 };
 
 static const uint8_t xive_tm_hv_view[] = {
     3, 0, 0, 0,   0, 0, 0, 0,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-0 User */
     3, 3, 3, 3,   3, 3, 0, 2,   3, 3, 3, 3,   0, 0, 0, 0, /* QW-1 OS   */
-    0, 0, 3, 3,   0, 0, 0, 0,   0, 3, 3, 3,   0, 0, 0, 0, /* QW-2 POOL */
+    0, 0, 3, 3,   0, 3, 3, 0,   0, 3, 3, 3,   0, 0, 0, 0, /* QW-2 POOL */
     3, 3, 3, 3,   0, 3, 0, 2,   3, 0, 0, 3,   0, 0, 0, 0, /* QW-3 PHYS */
 };
 
-- 
2.43.0