Re: [PATCH 15/50] ppc/xive: Move NSR decoding into helper functions

[Mike Kowal]

On 5/11/2025 10:10 PM, Nicholas Piggin wrote:

Rather than functions to return masks to test NSR bits, have functions
to test those bits directly. This should be no functional change, it
just makes the code more readable.

Reviewed-by: Michael Kowal <ko...@linux.ibm.com>

Thanks MAK

Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
  hw/intc/xive.c        | 51 +++++++++++++++++++++++++++++++++++--------
  include/hw/ppc/xive.h |  4 ++++
  2 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index bb40a69c5b..c2da23f9ea 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -25,6 +25,45 @@
  /*
   * XIVE Thread Interrupt Management context
   */
+bool xive_nsr_indicates_exception(uint8_t ring, uint8_t nsr)
+{
+    switch (ring) {
+    case TM_QW1_OS:
+        return !!(nsr & TM_QW1_NSR_EO);
+    case TM_QW2_HV_POOL:
+    case TM_QW3_HV_PHYS:
+        return !!(nsr & TM_QW3_NSR_HE);
+    default:
+        g_assert_not_reached();
+    }
+}
+
+bool xive_nsr_indicates_group_exception(uint8_t ring, uint8_t nsr)
+{
+    if ((nsr & TM_NSR_GRP_LVL) > 0) {
+        g_assert(xive_nsr_indicates_exception(ring, nsr));
+        return true;
+    }
+    return false;
+}
+
+uint8_t xive_nsr_exception_ring(uint8_t ring, uint8_t nsr)
+{
+    /* NSR determines if pool/phys ring is for phys or pool interrupt */
+    if ((ring == TM_QW3_HV_PHYS) || (ring == TM_QW2_HV_POOL)) {
+        uint8_t he = (nsr & TM_QW3_NSR_HE) >> 6;
+
+        if (he == TM_QW3_NSR_HE_PHYS) {
+            return TM_QW3_HV_PHYS;
+        } else if (he == TM_QW3_NSR_HE_POOL) {
+            return TM_QW2_HV_POOL;
+        } else {
+            /* Don't support LSI mode */
+            g_assert_not_reached();
+        }
+    }
+    return ring;
+}

static qemu_irq xive_tctx_output(XiveTCTX *tctx, uint8_t ring)

  {
@@ -48,18 +87,12 @@ static uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t 
ring)

qemu_irq_lower(xive_tctx_output(tctx, ring)); - if (regs[TM_NSR] != 0) {

+    if (xive_nsr_indicates_exception(ring, nsr)) {
          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) == (TM_QW3_NSR_HE_POOL << 6))) {
-            alt_ring = TM_QW2_HV_POOL;
-        } else {
-            alt_ring = ring;
-        }
+        alt_ring = xive_nsr_exception_ring(ring, nsr);
          alt_regs = &tctx->regs[alt_ring];

regs[TM_CPPR] = cppr;

@@ -68,7 +101,7 @@ static uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t 
ring)
           * If the interrupt was for a specific VP, reset the pending
           * buffer bit, otherwise clear the logical server indicator
           */
-        if (!(regs[TM_NSR] & TM_NSR_GRP_LVL)) {
+        if (!xive_nsr_indicates_group_exception(ring, nsr)) {
              alt_regs[TM_IPB] &= ~xive_priority_to_ipb(cppr);
          }

diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h

index 538f438681..28f0f1b79a 100644
--- a/include/hw/ppc/xive.h
+++ b/include/hw/ppc/xive.h
@@ -365,6 +365,10 @@ static inline uint32_t xive_tctx_word2(uint8_t *ring)
      return *((uint32_t *) &ring[TM_WORD2]);
  }

+bool xive_nsr_indicates_exception(uint8_t ring, uint8_t nsr);

+bool xive_nsr_indicates_group_exception(uint8_t ring, uint8_t nsr);
+uint8_t xive_nsr_exception_ring(uint8_t ring, uint8_t nsr);
+
  /*
   * XIVE Router
   */