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

Adds support for single byte writes to offset 0x15 of the TIMA address
space.  This offset holds the Logical Server Group Size (LGS) field.
The field is used to evenly distribute the interrupt load among the
members of a group, but is unused in the current implementation so we
just support the writing of the value for now.

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@redhat.com>
---
 hw/intc/xive.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index 8e62c7e75f..8605dd618f 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -341,6 +341,19 @@ static void xive_tm_set_os_cppr(XivePresenter *xptr, XiveTCTX *tctx,
     xive_tctx_set_cppr(tctx, TM_QW1_OS, value & 0xff);
 }
 
+static void xive_tctx_set_lgs(XiveTCTX *tctx, uint8_t ring, uint8_t lgs)
+{
+    uint8_t *regs = &tctx->regs[ring];
+
+    regs[TM_LGS] = lgs;
+}
+
+static void xive_tm_set_os_lgs(XivePresenter *xptr, XiveTCTX *tctx,
+                          hwaddr offset, uint64_t value, unsigned size)
+{
+    xive_tctx_set_lgs(tctx, TM_QW1_OS, value & 0xff);
+}
+
 /*
  * Adjust the IPB to allow a CPU to process event queues of other
  * priorities during one physical interrupt cycle.
@@ -525,6 +538,8 @@ static const XiveTmOp xive2_tm_operations[] = {
                                                      NULL },
     { XIVE_TM_HV_PAGE, TM_QW1_OS + TM_WORD2,      4, xive2_tm_push_os_ctx,
                                                      NULL },
+    { XIVE_TM_OS_PAGE, TM_QW1_OS + TM_LGS,        1, xive_tm_set_os_lgs,
+                                                     NULL },
     { XIVE_TM_HV_PAGE, TM_QW3_HV_PHYS + TM_CPPR,  1, xive_tm_set_hv_cppr,
                                                      NULL },
     { XIVE_TM_HV_PAGE, TM_QW3_HV_PHYS + TM_WORD2, 1, xive_tm_vt_push,
-- 
2.43.0