hw/riscv/riscv-iommu: add riscv_iommu_hpm_incr_ctr()

This function will increment a specific counter, generating an interrupt
when an overflow occurs.

Some extra changes in riscv-iommu.c  were required to add this new
helper in riscv-iommu-hpm.c:

- RISCVIOMMUContext was moved to riscv-iommu.h, making it visible in
  riscv-iommu-hpm.c;

- riscv_iommu_notify() is now public.

No behavior change is made since HPM support is not being advertised
yet.

Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250224190826.1858473-5-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 114 insertions, 0 deletions

diff --git a/hw/riscv/riscv-iommu-hpm.c b/hw/riscv/riscv-iommu-hpm.c
index 5833ab8956..8eca5ee17e 100644
--- a/hw/riscv/riscv-iommu-hpm.c
+++ b/hw/riscv/riscv-iommu-hpm.c
@@ -52,3 +52,117 @@ uint64_t riscv_iommu_hpmcycle_read(RISCVIOMMUState *s)
     return (ctr_val + get_cycles() - ctr_prev) |
         (cycle & RISCV_IOMMU_IOHPMCYCLES_OVF);
 }
+
+static void hpm_incr_ctr(RISCVIOMMUState *s, uint32_t ctr_idx)
+{
+    const uint32_t off = ctr_idx << 3;
+    uint64_t cntr_val;
+
+    cntr_val = ldq_le_p(&s->regs_rw[RISCV_IOMMU_REG_IOHPMCTR_BASE + off]);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_IOHPMCTR_BASE + off], cntr_val + 1);
+
+    /* Handle the overflow scenario. */
+    if (cntr_val == UINT64_MAX) {
+        /*
+         * Generate interrupt only if OF bit is clear. +1 to offset the cycle
+         * register OF bit.
+         */
+        const uint32_t ovf =
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_IOCOUNTOVF,
+                                  BIT(ctr_idx + 1), 0);
+        if (!get_field(ovf, BIT(ctr_idx + 1))) {
+            riscv_iommu_reg_mod64(s,
+                                  RISCV_IOMMU_REG_IOHPMEVT_BASE + off,
+                                  RISCV_IOMMU_IOHPMEVT_OF,
+                                  0);
+            riscv_iommu_notify(s, RISCV_IOMMU_INTR_PM);
+        }
+    }
+}
+
+void riscv_iommu_hpm_incr_ctr(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+                              unsigned event_id)
+{
+    const uint32_t inhibit = riscv_iommu_reg_get32(
+        s, RISCV_IOMMU_REG_IOCOUNTINH);
+    uint32_t did_gscid;
+    uint32_t pid_pscid;
+    uint32_t ctr_idx;
+    gpointer value;
+    uint32_t ctrs;
+    uint64_t evt;
+
+    if (!(s->cap & RISCV_IOMMU_CAP_HPM)) {
+        return;
+    }
+
+    value = g_hash_table_lookup(s->hpm_event_ctr_map,
+                                GUINT_TO_POINTER(event_id));
+    if (value == NULL) {
+        return;
+    }
+
+    for (ctrs = GPOINTER_TO_UINT(value); ctrs != 0; ctrs &= ctrs - 1) {
+        ctr_idx = ctz32(ctrs);
+        if (get_field(inhibit, BIT(ctr_idx + 1))) {
+            continue;
+        }
+
+        evt = riscv_iommu_reg_get64(s,
+            RISCV_IOMMU_REG_IOHPMEVT_BASE + (ctr_idx << 3));
+
+        /*
+         * It's quite possible that event ID has been changed in counter
+         * but hashtable hasn't been updated yet. We don't want to increment
+         * counter for the old event ID.
+         */
+        if (event_id != get_field(evt, RISCV_IOMMU_IOHPMEVT_EVENT_ID)) {
+            continue;
+        }
+
+        if (get_field(evt, RISCV_IOMMU_IOHPMEVT_IDT)) {
+            did_gscid = get_field(ctx->gatp, RISCV_IOMMU_DC_IOHGATP_GSCID);
+            pid_pscid = get_field(ctx->ta, RISCV_IOMMU_DC_TA_PSCID);
+        } else {
+            did_gscid = ctx->devid;
+            pid_pscid = ctx->process_id;
+        }
+
+        if (get_field(evt, RISCV_IOMMU_IOHPMEVT_PV_PSCV)) {
+            /*
+             * If the transaction does not have a valid process_id, counter
+             * increments if device_id matches DID_GSCID. If the transaction
+             * has a valid process_id, counter increments if device_id
+             * matches DID_GSCID and process_id matches PID_PSCID. See
+             * IOMMU Specification, Chapter 5.23. Performance-monitoring
+             * event selector.
+             */
+            if (ctx->process_id &&
+                get_field(evt, RISCV_IOMMU_IOHPMEVT_PID_PSCID) != pid_pscid) {
+                continue;
+            }
+        }
+
+        if (get_field(evt, RISCV_IOMMU_IOHPMEVT_DV_GSCV)) {
+            uint32_t mask = ~0;
+
+            if (get_field(evt, RISCV_IOMMU_IOHPMEVT_DMASK)) {
+                /*
+                 * 1001 1011   mask = GSCID
+                 * 0000 0111   mask = mask ^ (mask + 1)
+                 * 1111 1000   mask = ~mask;
+                 */
+                mask = get_field(evt, RISCV_IOMMU_IOHPMEVT_DID_GSCID);
+                mask = mask ^ (mask + 1);
+                mask = ~mask;
+            }
+
+            if ((get_field(evt, RISCV_IOMMU_IOHPMEVT_DID_GSCID) & mask) !=
+                (did_gscid & mask)) {
+                continue;
+            }
+        }
+
+        hpm_incr_ctr(s, ctr_idx);
+    }
+}