ppc/xive2: Reset Generation Flipped bit on END Cache Watch

When the END Event Queue wraps the END EQ Generation bit is flipped and the
Generation Flipped bit is set to one.  On a END cache Watch read operation,
the Generation Flipped bit needs to be reset.

While debugging an error modified END not valid error messages to include
the method since all were the same.

Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-8-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/intc/pnv_xive2.c b/hw/intc/pnv_xive2.c
index 6b724fe762f619aa35ad086f5311e77ca38458dc..ec247ce48ff733ccc4b31e55bbc80ec674aa14cb 100644 (file)
--- a/hw/intc/pnv_xive2.c
+++ b/hw/intc/pnv_xive2.c
@@ -1325,10 +1325,11 @@ static uint64_t pnv_xive2_ic_vc_read(void *opaque, hwaddr offset,
     case VC_ENDC_WATCH3_DATA0:
         /*
          * Load DATA registers from cache with data requested by the
-         * SPEC register
+         * SPEC register.  Clear gen_flipped bit in word 1.
          */
         watch_engine = (offset - VC_ENDC_WATCH0_DATA0) >> 6;
         pnv_xive2_end_cache_load(xive, watch_engine);
+        xive->vc_regs[reg] &= ~(uint64_t)END2_W1_GEN_FLIPPED;
         val = xive->vc_regs[reg];
         break;
 

diff --git a/hw/intc/xive2.c b/hw/intc/xive2.c
index 01cf96a2af65d6c6800358c3821df4e8fd2b6462..edf5d9eb94cb708b3fa9b473312657d34e2a0f87 100644 (file)
--- a/hw/intc/xive2.c
+++ b/hw/intc/xive2.c
@@ -374,8 +374,8 @@ static void xive2_end_enqueue(Xive2End *end, uint32_t data)
         qgen ^= 1;
         end->w1 = xive_set_field32(END2_W1_GENERATION, end->w1, qgen);
 
-        /* TODO(PowerNV): reset GF bit on a cache watch operation */
-        end->w1 = xive_set_field32(END2_W1_GEN_FLIPPED, end->w1, qgen);
+        /* Set gen flipped to 1, it gets reset on a cache watch operation */
+        end->w1 = xive_set_field32(END2_W1_GEN_FLIPPED, end->w1, 1);
     }
     end->w1 = xive_set_field32(END2_W1_PAGE_OFF, end->w1, qindex);
 }