[Qemu-devel] [PATCH 03/10] ppc/pnv: Rework cache watch model of PnvXIVE

[Cédric Le Goater]

When the software modifies the XIVE internal structures, ESB, EAS,
END, NVT, it also must update the caches of the different XIVE
sub-engines. HW offers a set of common interface for such purpose.

The CWATCH_SPEC register defines the block/index of the target and a
set of flags to perform a full update and to watch for update
conflicts.

The cache watch CWATCH_DATAX registers are then loaded with the target
data with a first read on CWATCH_DATA0. Writing back is done in the
opposit order, CWATCH_DATA0 triggering the update.

The SCRUB_TRIG registers are used to flush the cache in RAM, and to
possibly invalidate it. Cache disablement is also an option but as we
do not model the cache, these registers are no-ops

Today, the modeling of these registers is incorrect but it did not
impact the set up of a baremetal system. However, running KVM requires
a rework.

Fixes: 2dfa91a2aa5a ("ppc/pnv: add a XIVE interrupt controller model for 
POWER9")
Signed-off-by: Cédric Le Goater <address@hidden>
---
 hw/intc/pnv_xive.c | 142 +++++++++++++++++++++++++++++++++------------
 1 file changed, 106 insertions(+), 36 deletions(-)

diff --git a/hw/intc/pnv_xive.c b/hw/intc/pnv_xive.c
index 9ab77feee9d8..4dc92ef1e372 100644
--- a/hw/intc/pnv_xive.c
+++ b/hw/intc/pnv_xive.c
@@ -169,7 +169,7 @@ static uint64_t pnv_xive_vst_addr_indirect(PnvXive *xive, 
uint32_t type,
     vsd = ldq_be_dma(&address_space_memory, vsd_addr);
 
     if (!(vsd & VSD_ADDRESS_MASK)) {
-        xive_error(xive, "VST: invalid %s entry %x !?", info->name, 0);
+        xive_error(xive, "VST: invalid %s entry %x !?", info->name, idx);
         return 0;
     }
 
@@ -190,7 +190,7 @@ static uint64_t pnv_xive_vst_addr_indirect(PnvXive *xive, 
uint32_t type,
         vsd = ldq_be_dma(&address_space_memory, vsd_addr);
 
         if (!(vsd & VSD_ADDRESS_MASK)) {
-            xive_error(xive, "VST: invalid %s entry %x !?", info->name, 0);
+            xive_error(xive, "VST: invalid %s entry %x !?", info->name, idx);
             return 0;
         }
 
@@ -294,8 +294,12 @@ static int pnv_xive_write_end(XiveRouter *xrtr, uint8_t 
blk, uint32_t idx,
                               word_number);
 }
 
-static int pnv_xive_end_update(PnvXive *xive, uint8_t blk, uint32_t idx)
+static int pnv_xive_end_update(PnvXive *xive)
 {
+    uint8_t  blk = GETFIELD(VC_EQC_CWATCH_BLOCKID,
+                           xive->regs[(VC_EQC_CWATCH_SPEC >> 3)]);
+    uint32_t idx = GETFIELD(VC_EQC_CWATCH_OFFSET,
+                           xive->regs[(VC_EQC_CWATCH_SPEC >> 3)]);
     int i;
     uint64_t eqc_watch[4];
 
@@ -307,6 +311,24 @@ static int pnv_xive_end_update(PnvXive *xive, uint8_t blk, 
uint32_t idx)
                               XIVE_VST_WORD_ALL);
 }
 
+static void pnv_xive_end_cache_load(PnvXive *xive)
+{
+    uint8_t  blk = GETFIELD(VC_EQC_CWATCH_BLOCKID,
+                           xive->regs[(VC_EQC_CWATCH_SPEC >> 3)]);
+    uint32_t idx = GETFIELD(VC_EQC_CWATCH_OFFSET,
+                           xive->regs[(VC_EQC_CWATCH_SPEC >> 3)]);
+    uint64_t eqc_watch[4] = { 0 };
+    int i;
+
+    if (pnv_xive_vst_read(xive, VST_TSEL_EQDT, blk, idx, eqc_watch)) {
+        xive_error(xive, "VST: no END entry %x/%x !?", blk, idx);
+    }
+
+    for (i = 0; i < ARRAY_SIZE(eqc_watch); i++) {
+        xive->regs[(VC_EQC_CWATCH_DAT0 >> 3) + i] = be64_to_cpu(eqc_watch[i]);
+    }
+}
+
 static int pnv_xive_get_nvt(XiveRouter *xrtr, uint8_t blk, uint32_t idx,
                             XiveNVT *nvt)
 {
@@ -320,8 +342,12 @@ static int pnv_xive_write_nvt(XiveRouter *xrtr, uint8_t 
blk, uint32_t idx,
                               word_number);
 }
 
-static int pnv_xive_nvt_update(PnvXive *xive, uint8_t blk, uint32_t idx)
+static int pnv_xive_nvt_update(PnvXive *xive)
 {
+    uint8_t  blk = GETFIELD(PC_VPC_CWATCH_BLOCKID,
+                           xive->regs[(PC_VPC_CWATCH_SPEC >> 3)]);
+    uint32_t idx = GETFIELD(PC_VPC_CWATCH_OFFSET,
+                           xive->regs[(PC_VPC_CWATCH_SPEC >> 3)]);
     int i;
     uint64_t vpc_watch[8];
 
@@ -333,6 +359,24 @@ static int pnv_xive_nvt_update(PnvXive *xive, uint8_t blk, 
uint32_t idx)
                               XIVE_VST_WORD_ALL);
 }
 
+static void pnv_xive_nvt_cache_load(PnvXive *xive)
+{
+    uint8_t  blk = GETFIELD(PC_VPC_CWATCH_BLOCKID,
+                           xive->regs[(PC_VPC_CWATCH_SPEC >> 3)]);
+    uint32_t idx = GETFIELD(PC_VPC_CWATCH_OFFSET,
+                           xive->regs[(PC_VPC_CWATCH_SPEC >> 3)]);
+    uint64_t vpc_watch[8] = { 0 };
+    int i;
+
+    if (pnv_xive_vst_read(xive, VST_TSEL_VPDT, blk, idx, vpc_watch)) {
+        xive_error(xive, "VST: no NVT entry %x/%x !?", blk, idx);
+    }
+
+    for (i = 0; i < ARRAY_SIZE(vpc_watch); i++) {
+        xive->regs[(PC_VPC_CWATCH_DAT0 >> 3) + i] = be64_to_cpu(vpc_watch[i]);
+    }
+}
+
 static int pnv_xive_get_eas(XiveRouter *xrtr, uint8_t blk, uint32_t idx,
                             XiveEAS *eas)
 {
@@ -346,12 +390,6 @@ static int pnv_xive_get_eas(XiveRouter *xrtr, uint8_t blk, 
uint32_t idx,
     return pnv_xive_vst_read(xive, VST_TSEL_IVT, blk, idx, eas);
 }
 
-static int pnv_xive_eas_update(PnvXive *xive, uint8_t blk, uint32_t idx)
-{
-    /* All done. */
-    return 0;
-}
-
 static XiveTCTX *pnv_xive_get_tctx(XiveRouter *xrtr, CPUState *cs)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
@@ -950,28 +988,43 @@ static void pnv_xive_ic_reg_write(void *opaque, hwaddr 
offset,
      * XIVE PC & VC cache updates for EAS, NVT and END
      */
     case VC_IVC_SCRUB_MASK:
-        break;
     case VC_IVC_SCRUB_TRIG:
-        pnv_xive_eas_update(xive, GETFIELD(PC_SCRUB_BLOCK_ID, val),
-                            GETFIELD(VC_SCRUB_OFFSET, val));
         break;
 
-    case VC_EQC_SCRUB_MASK:
     case VC_EQC_CWATCH_SPEC:
-    case VC_EQC_CWATCH_DAT0 ... VC_EQC_CWATCH_DAT3:
+        val &= ~VC_EQC_CWATCH_CONFLICT; /* HW resets this bit */
+        break;
+    case VC_EQC_CWATCH_DAT1 ... VC_EQC_CWATCH_DAT3:
         break;
+    case VC_EQC_CWATCH_DAT0:
+        /* writing to DATA0 triggers the cache write */
+        xive->regs[reg] = val;
+        pnv_xive_end_update(xive);
+        break;
+    case VC_EQC_SCRUB_MASK:
     case VC_EQC_SCRUB_TRIG:
-        pnv_xive_end_update(xive, GETFIELD(VC_SCRUB_BLOCK_ID, val),
-                            GETFIELD(VC_SCRUB_OFFSET, val));
+        /*
+         * The scrubbing registers flush the cache in RAM and can also
+         * invalidate.
+         */
         break;
 
-    case PC_VPC_SCRUB_MASK:
     case PC_VPC_CWATCH_SPEC:
-    case PC_VPC_CWATCH_DAT0 ... PC_VPC_CWATCH_DAT7:
+        val &= ~PC_VPC_CWATCH_CONFLICT; /* HW resets this bit */
+        break;
+    case PC_VPC_CWATCH_DAT1 ... PC_VPC_CWATCH_DAT7:
         break;
+    case PC_VPC_CWATCH_DAT0:
+        /* writing to DATA0 triggers the cache write */
+        xive->regs[reg] = val;
+        pnv_xive_nvt_update(xive);
+        break;
+    case PC_VPC_SCRUB_MASK:
     case PC_VPC_SCRUB_TRIG:
-        pnv_xive_nvt_update(xive, GETFIELD(PC_SCRUB_BLOCK_ID, val),
-                           GETFIELD(PC_SCRUB_OFFSET, val));
+        /*
+         * The scrubbing registers flush the cache in RAM and can also
+         * invalidate.
+         */
         break;
 
 
@@ -1022,15 +1075,6 @@ static uint64_t pnv_xive_ic_reg_read(void *opaque, 
hwaddr offset, unsigned size)
     case PC_GLOBAL_CONFIG:
 
     case PC_VPC_SCRUB_MASK:
-    case PC_VPC_CWATCH_SPEC:
-    case PC_VPC_CWATCH_DAT0:
-    case PC_VPC_CWATCH_DAT1:
-    case PC_VPC_CWATCH_DAT2:
-    case PC_VPC_CWATCH_DAT3:
-    case PC_VPC_CWATCH_DAT4:
-    case PC_VPC_CWATCH_DAT5:
-    case PC_VPC_CWATCH_DAT6:
-    case PC_VPC_CWATCH_DAT7:
 
     case VC_GLOBAL_CONFIG:
     case VC_AIB_TX_ORDER_TAG2:
@@ -1043,12 +1087,6 @@ static uint64_t pnv_xive_ic_reg_read(void *opaque, 
hwaddr offset, unsigned size)
     case VC_IRQ_CONFIG_IPI_CASC:
 
     case VC_EQC_SCRUB_MASK:
-    case VC_EQC_CWATCH_DAT0:
-    case VC_EQC_CWATCH_DAT1:
-    case VC_EQC_CWATCH_DAT2:
-    case VC_EQC_CWATCH_DAT3:
-
-    case VC_EQC_CWATCH_SPEC:
     case VC_IVC_SCRUB_MASK:
     case VC_SBC_CONFIG:
     case VC_AT_MACRO_KILL_MASK:
@@ -1080,6 +1118,38 @@ static uint64_t pnv_xive_ic_reg_read(void *opaque, 
hwaddr offset, unsigned size)
     /*
      * XIVE PC & VC cache updates for EAS, NVT and END
      */
+    case VC_EQC_CWATCH_SPEC:
+        xive->regs[reg] = ~(VC_EQC_CWATCH_FULL | VC_EQC_CWATCH_CONFLICT);
+        val = xive->regs[reg];
+        break;
+    case VC_EQC_CWATCH_DAT0:
+        /*
+         * Load DATA registers from cache with data requested by the
+         * SPEC register
+         */
+        pnv_xive_end_cache_load(xive);
+        val = xive->regs[reg];
+        break;
+    case VC_EQC_CWATCH_DAT1 ... VC_EQC_CWATCH_DAT3:
+        val = xive->regs[reg];
+        break;
+
+    case PC_VPC_CWATCH_SPEC:
+        xive->regs[reg] = ~(PC_VPC_CWATCH_FULL | PC_VPC_CWATCH_CONFLICT);
+        val = xive->regs[reg];
+        break;
+    case PC_VPC_CWATCH_DAT0:
+        /*
+         * Load DATA registers from cache with data requested by the
+         * SPEC register
+         */
+        pnv_xive_nvt_cache_load(xive);
+        val = xive->regs[reg];
+        break;
+    case PC_VPC_CWATCH_DAT1 ... PC_VPC_CWATCH_DAT7:
+        val = xive->regs[reg];
+        break;
+
     case PC_VPC_SCRUB_TRIG:
     case VC_IVC_SCRUB_TRIG:
     case VC_EQC_SCRUB_TRIG:
-- 
2.21.0