On 1/29/26 4:52 PM, Eric Farman wrote:
On Tue, 2026-01-27 at 11:15 -0500, [email protected] wrote:
From: Jared Rossi <[email protected]>
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.
Signed-off-by: Jared Rossi <[email protected]>
---
pc-bios/s390-ccw/Makefile | 2 +-
pc-bios/s390-ccw/clp.c | 96 +++++++++++++++++++++++++++++++++++++++
pc-bios/s390-ccw/clp.h | 24 ++++++++++
3 files changed, 121 insertions(+), 1 deletion(-)
create mode 100644 pc-bios/s390-ccw/clp.c
create mode 100644 pc-bios/s390-ccw/clp.h
First off, this looks like correct according to my reading.
My only question is whether we need any breadcrumbs in case things fail?
Dumping the requested FID
in case of an enable, or the response code in either case? (I haven't gotten to
the later patches
yet, just looking at the puts here has me wondering if that's enough of a clue.)
Improving the logging makes sense; I'll add more useful output.
Thanks,
Jared Rossi
diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index 259cff09db..9c29548f84 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/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
diff --git a/pc-bios/s390-ccw/clp.c b/pc-bios/s390-ccw/clp.c
new file mode 100644
index 0000000000..2a14bb9b73
--- /dev/null
+++ b/pc-bios/s390-ccw/clp.c
@@ -0,0 +1,96 @@
+/*
+ * Call Logical Processor (CLP) architecture
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <[email protected]>
+ *
+ * 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 _[2048]; } *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");
+ 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 = 32;
+ 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 enteries 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 = 32;
+ rrb.request.hdr.cmd = 0x05;
+ rrb.request.fh = *fhandle;
+ rrb.request.oc = 0;
+ rrb.request.ndas = 1;
+ rrb.response.hdr.len = 32;
+
+ if (clp_pci(&rrb) || rrb.response.hdr.rsp != 0x0010) {
+ puts("Failed to enable PCI function");
+ return -1;
+ }
+
+ *fhandle = rrb.response.fh;
+ return 0;
+}
diff --git a/pc-bios/s390-ccw/clp.h b/pc-bios/s390-ccw/clp.h
new file mode 100644
index 0000000000..1ac2f8c177
--- /dev/null
+++ b/pc-bios/s390-ccw/clp.h
@@ -0,0 +1,24 @@
+/*
+ * Call Logical Processor (CLP) architecture definitions
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <[email protected]>
+ *
+ * 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
