pc-bios/s390-ccw: Introduce CLP Architecture

Call Logical Processor (CLP) Architecture is used for managing PCI functions on
s390x. Define and include the structures and routines needed to interact with
PCI devices during IPL.

Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Message-ID: <20260309003601.242634-9-jrossi@linux.ibm.com>
[thuth: fix a typo in one of the comments]
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/Makefile

@@ -35,7 +35,7 @@ QEMU_DGFLAGS = -MMD -MP -MT $@ -MF $(@D)/$(*F).d
 
 OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.o netmain.o \
 	  virtio.o virtio-net.o virtio-scsi.o virtio-blkdev.o cio.o dasd-ipl.o \
-	  virtio-ccw.o
+	  virtio-ccw.o clp.o
 
 SLOF_DIR := $(SRC_PATH)/../../roms/SLOF
 

pc-bios/s390-ccw/clp.c

@@ -0,0 +1,99 @@
+/*
+ * Call Logical Processor (CLP) architecture
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <jrossi@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "clp.h"
+#include <stdio.h>
+#include <string.h>
+
+int clp_pci(void *data)
+{
+    struct { uint8_t _[CLP_BLK_SIZE]; } *req = data;
+    int cc = 3;
+
+    asm volatile (
+        "     .insn   rrf,0xb9a00000,0,%[req],0,2\n"
+        "     ipm     %[cc]\n"
+        "     srl     %[cc],28\n"
+        : [cc] "+d" (cc), "+m" (*req)
+        : [req] "a" (req)
+        : "cc");
+    if (cc) {
+        printf("CLP returned with non-zero condition code %d\n", cc);
+    }
+    return cc;
+}
+
+/*
+ * Get the PCI function entry for a given function ID
+ * Return 0 on success, 1 if the FID is not found, or a negative RC on error
+ */
+int find_pci_function(uint32_t fid, ClpFhListEntry *entry)
+{
+    int count = 0;
+    int limit = PCI_MAX_FUNCTIONS;
+    ClpReqRspListPci rrb;
+
+    rrb.request.hdr.len = sizeof(ClpReqListPci);
+    rrb.request.hdr.cmd = 0x02;
+    rrb.request.resume_token = 0;
+    rrb.response.hdr.len = sizeof(ClpRspListPci);
+
+    do {
+        if (clp_pci(&rrb) || rrb.response.hdr.rsp != 0x0010) {
+            puts("Failed to list PCI functions");
+            return -1;
+        }
+
+        /* Resume token set when max entries are returned */
+        if (rrb.response.resume_token) {
+            count = CLP_FH_LIST_NR_ENTRIES;
+            rrb.request.resume_token = rrb.response.resume_token;
+        } else {
+            count = (rrb.response.hdr.len - 32) / sizeof(ClpFhListEntry);
+        }
+
+        limit -= count;
+
+        for (int i = 0; i < count; i++) {
+            if (rrb.response.fh_list[i].fid == fid) {
+                memcpy(entry, &rrb.response.fh_list[i], sizeof(ClpFhListEntry));
+                return 0;
+            }
+        }
+
+    } while (rrb.request.resume_token && limit > 0);
+
+    puts("No function entry found for FID!");
+
+    return 1;
+}
+
+/*
+ * Enable the PCI function associated with a given handle
+ * Return 0 on success or a negative RC on error
+ */
+int enable_pci_function(uint32_t *fhandle)
+{
+    ClpReqRspSetPci rrb;
+
+    rrb.request.hdr.len = sizeof(ClpReqSetPci);
+    rrb.request.hdr.cmd = 0x05;
+    rrb.request.fh = *fhandle;
+    rrb.request.oc = 0;
+    rrb.request.ndas = 1;
+    rrb.response.hdr.len = sizeof(ClpRspSetPci);
+
+    if (clp_pci(&rrb) || rrb.response.hdr.rsp != 0x0010) {
+        puts("Failed to enable PCI function");
+        return -1;
+    }
+
+    *fhandle = rrb.response.fh;
+    return 0;
+}

pc-bios/s390-ccw/clp.h

@@ -0,0 +1,24 @@
+/*
+ * Call Logical Processor (CLP) architecture definitions
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <jrossi@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef CLP_H
+#define CLP_H
+
+#ifndef QEMU_PACKED
+#define QEMU_PACKED __attribute__((packed))
+#endif
+
+#include <stdint.h>
+#include <s390-pci-clp.h>
+
+int clp_pci(void *data);
+int find_pci_function(uint32_t fid, ClpFhListEntry *entry);
+int enable_pci_function(uint32_t *fhandle);
+
+#endif