[PATCH v2 06/14] ppc/xive2: Process group backlog when updating the CPPR

[Michael Kowal]

From: Frederic Barrat <fbarrat@linux.ibm.com>

When the hypervisor or OS pushes a new value to the CPPR, if the LSMFB
value is lower than the new CPPR value, there could be a pending group
interrupt in the backlog, so it needs to be scanned.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
---
 include/hw/ppc/xive2.h |   4 +
 hw/intc/xive.c         |   4 +-
 hw/intc/xive2.c        | 173 ++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 177 insertions(+), 4 deletions(-)

diff --git a/include/hw/ppc/xive2.h b/include/hw/ppc/xive2.h
index d88db05687..e61b978f37 100644
--- a/include/hw/ppc/xive2.h
+++ b/include/hw/ppc/xive2.h
@@ -115,6 +115,10 @@ typedef struct Xive2EndSource {
  * XIVE2 Thread Interrupt Management Area (POWER10)
  */
 
+void xive2_tm_set_hv_cppr(XivePresenter *xptr, XiveTCTX *tctx,
+                          hwaddr offset, uint64_t value, unsigned size);
+void xive2_tm_set_os_cppr(XivePresenter *xptr, XiveTCTX *tctx,
+                          hwaddr offset, uint64_t value, unsigned size);
 void xive2_tm_push_os_ctx(XivePresenter *xptr, XiveTCTX *tctx, hwaddr offset,
                            uint64_t value, unsigned size);
 uint64_t xive2_tm_pull_os_ctx(XivePresenter *xptr, XiveTCTX *tctx,
diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index 9345cddead..74a78da88b 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -603,7 +603,7 @@ static const XiveTmOp xive2_tm_operations[] = {
      * MMIOs below 2K : raw values and special operations without side
      * effects
      */
-    { XIVE_TM_OS_PAGE, TM_QW1_OS + TM_CPPR,       1, xive_tm_set_os_cppr,
+    { XIVE_TM_OS_PAGE, TM_QW1_OS + TM_CPPR,       1, xive2_tm_set_os_cppr,
                                                      NULL },
     { XIVE_TM_HV_PAGE, TM_QW1_OS + TM_WORD2,      4, xive2_tm_push_os_ctx,
                                                      NULL },
@@ -611,7 +611,7 @@ static const XiveTmOp xive2_tm_operations[] = {
                                                      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,
+    { XIVE_TM_HV_PAGE, TM_QW3_HV_PHYS + TM_CPPR,  1, xive2_tm_set_hv_cppr,
                                                      NULL },
     { XIVE_TM_HV_PAGE, TM_QW3_HV_PHYS + TM_WORD2, 1, xive_tm_vt_push,
                                                      NULL },
diff --git a/hw/intc/xive2.c b/hw/intc/xive2.c
index 7130892482..0c53f71879 100644
--- a/hw/intc/xive2.c
+++ b/hw/intc/xive2.c
@@ -18,6 +18,7 @@
 #include "hw/ppc/xive.h"
 #include "hw/ppc/xive2.h"
 #include "hw/ppc/xive2_regs.h"
+#include "trace.h"
 
 uint32_t xive2_router_get_config(Xive2Router *xrtr)
 {
@@ -764,6 +765,172 @@ void xive2_tm_push_os_ctx(XivePresenter *xptr, XiveTCTX 
*tctx,
     }
 }
 
+static int xive2_tctx_get_nvp_indexes(XiveTCTX *tctx, uint8_t ring,
+                                      uint32_t *nvp_blk, uint32_t *nvp_idx)
+{
+    uint32_t w2, cam;
+
+    w2 = xive_tctx_word2(&tctx->regs[ring]);
+    switch (ring) {
+    case TM_QW1_OS:
+        if (!(be32_to_cpu(w2) & TM2_QW1W2_VO)) {
+            return -1;
+        }
+        cam = xive_get_field32(TM2_QW1W2_OS_CAM, w2);
+        break;
+    case TM_QW2_HV_POOL:
+        if (!(be32_to_cpu(w2) & TM2_QW2W2_VP)) {
+            return -1;
+        }
+        cam = xive_get_field32(TM2_QW2W2_POOL_CAM, w2);
+        break;
+    case TM_QW3_HV_PHYS:
+        if (!(be32_to_cpu(w2) & TM2_QW3W2_VT)) {
+            return -1;
+        }
+        cam = xive2_tctx_hw_cam_line(tctx->xptr, tctx);
+        break;
+    default:
+        return -1;
+    }
+    *nvp_blk = xive2_nvp_blk(cam);
+    *nvp_idx = xive2_nvp_idx(cam);
+    return 0;
+}
+
+static void xive2_tctx_set_cppr(XiveTCTX *tctx, uint8_t ring, uint8_t cppr)
+{
+    uint8_t *regs = &tctx->regs[ring];
+    Xive2Router *xrtr = XIVE2_ROUTER(tctx->xptr);
+    uint8_t old_cppr, backlog_prio, first_group, group_level = 0;
+    uint8_t pipr_min, lsmfb_min, ring_min;
+    bool group_enabled;
+    uint32_t nvp_blk, nvp_idx;
+    Xive2Nvp nvp;
+    int rc;
+
+    trace_xive_tctx_set_cppr(tctx->cs->cpu_index, ring,
+                             regs[TM_IPB], regs[TM_PIPR],
+                             cppr, regs[TM_NSR]);
+
+    if (cppr > XIVE_PRIORITY_MAX) {
+        cppr = 0xff;
+    }
+
+    old_cppr = regs[TM_CPPR];
+    regs[TM_CPPR] = cppr;
+
+    /*
+     * Recompute the PIPR based on local pending interrupts. It will
+     * be adjusted below if needed in case of pending group interrupts.
+     */
+    pipr_min = xive_ipb_to_pipr(regs[TM_IPB]);
+    group_enabled = !!regs[TM_LGS];
+    lsmfb_min = (group_enabled) ? regs[TM_LSMFB] : 0xff;
+    ring_min = ring;
+
+    /* PHYS updates also depend on POOL values */
+    if (ring == TM_QW3_HV_PHYS) {
+        uint8_t *pregs = &tctx->regs[TM_QW2_HV_POOL];
+
+        /* POOL values only matter if POOL ctx is valid */
+        if (pregs[TM_WORD2] & 0x80) {
+
+            uint8_t pool_pipr = xive_ipb_to_pipr(pregs[TM_IPB]);
+            uint8_t pool_lsmfb = pregs[TM_LSMFB];
+
+            /*
+             * Determine highest priority interrupt and
+             * remember which ring has it.
+             */
+            if (pool_pipr < pipr_min) {
+                pipr_min = pool_pipr;
+                if (pool_pipr < lsmfb_min) {
+                    ring_min = TM_QW2_HV_POOL;
+                }
+            }
+
+            /* Values needed for group priority calculation */
+            if (pregs[TM_LGS] && (pool_lsmfb < lsmfb_min)) {
+                group_enabled = true;
+                lsmfb_min = pool_lsmfb;
+                if (lsmfb_min < pipr_min) {
+                    ring_min = TM_QW2_HV_POOL;
+                }
+            }
+        }
+    }
+    regs[TM_PIPR] = pipr_min;
+
+    rc = xive2_tctx_get_nvp_indexes(tctx, ring_min, &nvp_blk, &nvp_idx);
+    if (rc) {
+        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: set CPPR on invalid context\n");
+        return;
+    }
+
+    if (cppr < old_cppr) {
+        /*
+         * FIXME: check if there's a group interrupt being presented
+         * and if the new cppr prevents it. If so, then the group
+         * interrupt needs to be re-added to the backlog and
+         * re-triggered (see re-trigger END info in the NVGC
+         * structure)
+         */
+    }
+
+    if (group_enabled &&
+        lsmfb_min < cppr &&
+        lsmfb_min < regs[TM_PIPR]) {
+        /*
+         * Thread has seen a group interrupt with a higher priority
+         * than the new cppr or pending local interrupt. Check the
+         * backlog
+         */
+        if (xive2_router_get_nvp(xrtr, nvp_blk, nvp_idx, &nvp)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "XIVE: No NVP %x/%x\n",
+                          nvp_blk, nvp_idx);
+            return;
+        }
+
+        if (!xive2_nvp_is_valid(&nvp)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid NVP %x/%x\n",
+                          nvp_blk, nvp_idx);
+            return;
+        }
+
+        first_group = xive_get_field32(NVP2_W0_PGOFIRST, nvp.w0);
+        if (!first_group) {
+            qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid NVP %x/%x\n",
+                          nvp_blk, nvp_idx);
+            return;
+        }
+
+        backlog_prio = xive2_presenter_backlog_check(tctx->xptr,
+                                                     nvp_blk, nvp_idx,
+                                                     first_group, 
&group_level);
+        tctx->regs[ring_min + TM_LSMFB] = backlog_prio;
+        if (backlog_prio != 0xFF) {
+            xive2_presenter_backlog_decr(tctx->xptr, nvp_blk, nvp_idx,
+                                         backlog_prio, group_level);
+            regs[TM_PIPR] = backlog_prio;
+        }
+    }
+    /* CPPR has changed, check if we need to raise a pending exception */
+    xive_tctx_notify(tctx, ring_min, group_level);
+}
+
+void xive2_tm_set_hv_cppr(XivePresenter *xptr, XiveTCTX *tctx,
+                          hwaddr offset, uint64_t value, unsigned size)
+{
+    xive2_tctx_set_cppr(tctx, TM_QW3_HV_PHYS, value & 0xff);
+}
+
+void xive2_tm_set_os_cppr(XivePresenter *xptr, XiveTCTX *tctx,
+                          hwaddr offset, uint64_t value, unsigned size)
+{
+    xive2_tctx_set_cppr(tctx, TM_QW1_OS, value & 0xff);
+}
+
 static void xive2_tctx_set_target(XiveTCTX *tctx, uint8_t ring, uint8_t target)
 {
     uint8_t *regs = &tctx->regs[ring];
@@ -934,7 +1101,9 @@ int xive2_presenter_tctx_match(XivePresenter *xptr, 
XiveTCTX *tctx,
 
 bool xive2_tm_irq_precluded(XiveTCTX *tctx, int ring, uint8_t priority)
 {
-    uint8_t *regs = &tctx->regs[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];
 
     /*
      * The xive2_presenter_tctx_match() above tells if there's a match
@@ -942,7 +1111,7 @@ bool xive2_tm_irq_precluded(XiveTCTX *tctx, int ring, 
uint8_t priority)
      * priority to know if the thread can take the interrupt now or if
      * it is precluded.
      */
-    if (priority < regs[TM_CPPR]) {
+    if (priority < alt_regs[TM_CPPR]) {
         return false;
     }
     return true;
-- 
2.43.0