[kvm-unit-tests PATCH] s390x: Add initial smp code

Janosch Frank
2019-09-23T14:18:16Z

Let's add a rudimentary SMP library, which will scan for cpus and has
helper functions that manage the cpu state.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---

I left the setup code untouched, as I didn't want to indent too many
lines.

---
lib/s390x/asm/arch_def.h | 8 ++
lib/s390x/asm/sigp.h | 28 ++++-
lib/s390x/io.c | 5 +-
lib/s390x/sclp.h | 1 +
lib/s390x/smp.c | 252 +++++++++++++++++++++++++++++++++++++++
lib/s390x/smp.h | 51 ++++++++
s390x/Makefile | 1 +
s390x/cstart64.S | 7 ++
8 files changed, 347 insertions(+), 6 deletions(-)
create mode 100644 lib/s390x/smp.c
create mode 100644 lib/s390x/smp.h

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 5f8f45e..d5a7f51 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -157,6 +157,14 @@ struct cpuid {
uint64_t reserved : 15;
};

+static inline unsigned short stap(void)
+{
+ unsigned short cpu_address;
+
+ asm volatile("stap %0" : "=Q" (cpu_address));
+ return cpu_address;
+}
+
static inline int tprot(unsigned long addr)
{
int cc;
diff --git a/lib/s390x/asm/sigp.h b/lib/s390x/asm/sigp.h
index fbd94fc..2d52313 100644
--- a/lib/s390x/asm/sigp.h
+++ b/lib/s390x/asm/sigp.h
@@ -46,14 +46,32 @@

#ifndef __ASSEMBLER__

-static inline void sigp_stop(void)
+
+static inline int sigp(uint16_t addr, uint8_t order, unsigned long parm,
+ uint32_t *status)
{
- register unsigned long status asm ("1") = 0;
- register unsigned long cpu asm ("2") = 0;
+ register unsigned long reg1 asm ("1") = parm;
+ int cc;

asm volatile(
- " sigp %0,%1,0(%2)\n"
- : "+d" (status) : "d" (cpu), "d" (SIGP_STOP) : "cc");
+ " sigp %1,%2,0(%3)\n"
+ " ipm %0\n"
+ " srl %0,28\n"
+ : "=d" (cc), "+d" (reg1) : "d" (addr), "a" (order) : "cc");
+ if (status)
+ *status = reg1;
+ return cc;
+}
+
+static inline int sigp_retry(uint16_t addr, uint8_t order, unsigned long parm,
+ uint32_t *status)
+{
+ int cc;
+
+ do {
+ cc = sigp(addr, order, parm, status);
+ } while (cc == 2);
+ return cc;
}

#endif /* __ASSEMBLER__ */
diff --git a/lib/s390x/io.c b/lib/s390x/io.c
index becadfc..32f09b5 100644
--- a/lib/s390x/io.c
+++ b/lib/s390x/io.c
@@ -16,6 +16,7 @@
#include <asm/facility.h>
#include <asm/sigp.h>
#include "sclp.h"
+#include "smp.h"

extern char ipl_args[];
uint8_t stfl_bytes[NR_STFL_BYTES] __attribute__((aligned(8)));
@@ -37,12 +38,14 @@ void setup(void)
setup_facilities();
sclp_console_setup();
sclp_memory_setup();
+ smp_setup();
}

void exit(int code)
{
+ smp_teardown();
printf("\nEXIT: STATUS=%d\n", ((code) << 1) | 1);
while (1) {
- sigp_stop();
+ sigp(0, SIGP_STOP, 0, NULL);
}
}
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 98c482a..4e69845 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -19,6 +19,7 @@
#define SCLP_CMD_CODE_MASK 0xffff00ff

/* SCLP command codes */
+#define SCLP_READ_CPU_INFO 0x00010001
#define SCLP_CMDW_READ_SCP_INFO 0x00020001
#define SCLP_CMDW_READ_SCP_INFO_FORCED 0x00120001
#define SCLP_READ_STORAGE_ELEMENT_INFO 0x00040001
diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
new file mode 100644
index 0000000..7602886
--- /dev/null
+++ b/lib/s390x/smp.c
@@ -0,0 +1,252 @@
+/*
+ * s390x smp
+ * Based on Linux's arch/s390/kernel/smp.c and
+ * arch/s390/include/asm/sigp.h
+ *
+ * Copyright (c) 2019 IBM Corp
+ *
+ * Authors:
+ * Janosch Frank <frankja@linux.ibm.com>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2.
+ */
+#include <libcflat.h>
+#include <asm/arch_def.h>
+#include <asm/sigp.h>
+#include <asm/page.h>
+#include <asm/barrier.h>
+#include <asm/spinlock.h>
+#include <asm/asm-offsets.h>
+
+#include <alloc.h>
+#include <alloc_page.h>
+
+#include "smp.h"
+#include "sclp.h"
+
+static char cpu_info_buffer[PAGE_SIZE] __attribute__((__aligned__(4096)));
+static struct cpu *cpus;
+static struct cpu *cpu0;
+static struct spinlock lock;
+
+extern void smp_cpu_setup_state(void);
+
+int smp_query_num_cpus(void)
+{
+ struct ReadCpuInfo *info = (void *)cpu_info_buffer;
+ return info->nr_configured;
+}
+
+struct cpu *smp_cpu_from_addr(uint16_t addr)
+{
+ int i, num = smp_query_num_cpus();
+
+ for (i = 0; i < num; i++) {
+ if (cpus[i].addr == addr)
+ return &cpus[i];
+ }
+ return NULL;
+}
+
+bool smp_cpu_stopped(uint16_t addr)
+{
+ uint32_t status;
+
+ if (sigp(addr, SIGP_SENSE, 0, &status) != SIGP_CC_STATUS_STORED)
+ return false;
+ return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
+}
+
+bool smp_cpu_running(uint16_t addr)
+{
+ if (sigp(addr, SIGP_SENSE_RUNNING, 0, NULL) != SIGP_CC_STATUS_STORED)
+ return true;
+ /* Status stored condition code is equivalent to cpu not running. */
+ return false;
+}
+
+static int smp_cpu_stop_nolock(uint16_t addr, bool store)
+{
+ struct cpu *cpu;
+ uint8_t order = store ? SIGP_STOP_AND_STORE_STATUS : SIGP_STOP;
+
+ cpu = smp_cpu_from_addr(addr);
+ if (!cpu || cpu == cpu0)
+ return -1;
+
+ if (sigp_retry(addr, order, 0, NULL))
+ return -1;
+
+ while (!smp_cpu_stopped(addr))
+ mb();
+ cpu->active = false;
+ return 0;
+}
+
+int smp_cpu_stop(uint16_t addr)
+{
+ int rc;
+
+ spin_lock(&lock);
+ rc = smp_cpu_stop_nolock(addr, false);
+ spin_unlock(&lock);
+ return rc;
+}
+
+int smp_cpu_stop_store_status(uint16_t addr)
+{
+ int rc;
+
+ spin_lock(&lock);
+ rc = smp_cpu_stop_nolock(addr, true);
+ spin_unlock(&lock);
+ return rc;
+}
+
+int smp_cpu_restart(uint16_t addr)
+{
+ int rc = -1;
+ struct cpu *cpu;
+
+ spin_lock(&lock);
+ cpu = smp_cpu_from_addr(addr);
+ if (cpu) {
+ rc = sigp(addr, SIGP_RESTART, 0, NULL);
+ cpu->active = true;
+ }
+ spin_unlock(&lock);
+ return rc;
+}
+
+int smp_cpu_start(uint16_t addr, struct psw psw)
+{
+ int rc = -1;
+ struct cpu *cpu;
+ struct lowcore *lc;
+
+ spin_lock(&lock);
+ cpu = smp_cpu_from_addr(addr);
+ if (cpu) {
+ lc = cpu->lowcore;
+ lc->restart_new_psw.mask = psw.mask;
+ lc->restart_new_psw.addr = psw.addr;
+ rc = sigp(addr, SIGP_RESTART, 0, NULL);
+ }
+ spin_unlock(&lock);
+ return rc;
+}
+
+int smp_cpu_destroy(uint16_t addr)
+{
+ struct cpu *cpu;
+ int rc;
+
+ spin_lock(&lock);
+ rc = smp_cpu_stop_nolock(addr, false);
+ if (!rc) {
+ cpu = smp_cpu_from_addr(addr);
+ free_pages(cpu->lowcore, 2 * PAGE_SIZE);
+ free_pages(cpu->stack, 4 * PAGE_SIZE);
+ cpu->lowcore = (void *)-1UL;
+ cpu->stack = (void *)-1UL;
+ }
+ spin_unlock(&lock);
+ return rc;
+}
+
+int smp_cpu_setup(uint16_t addr, struct psw psw)
+{
+ struct lowcore *lc;
+ struct cpu *cpu;
+ int rc = -1;
+
+ spin_lock(&lock);
+
+ if (!cpus)
+ goto out;
+
+ cpu = smp_cpu_from_addr(addr);
+
+ if (!cpu || cpu->active)
+ goto out;
+
+ sigp_retry(cpu->addr, SIGP_INITIAL_CPU_RESET, 0, NULL);
+
+ lc = alloc_pages(1);
+ cpu->lowcore = lc;
+ memset(lc, 0, PAGE_SIZE * 2);
+ sigp_retry(cpu->addr, SIGP_SET_PREFIX, (unsigned long )lc, NULL);
+
+ /* Copy all exception psws. */
+ memcpy(lc, cpu0->lowcore, 512);
+
+ /* Setup stack */
+ cpu->stack = (uint64_t *)alloc_pages(2);
+
+ /* Start without DAT and any other mask bits. */
+ cpu->lowcore->sw_int_grs[14] = psw.addr;
+ cpu->lowcore->sw_int_grs[15] = (uint64_t)cpu->stack + (PAGE_SIZE * 4);
+ lc->restart_new_psw.mask = 0x0000000180000000UL;
+ lc->restart_new_psw.addr = (uint64_t)smp_cpu_setup_state;
+ lc->sw_int_cr0 = 0x0000000000040000UL;
+
+ /* Start processing */
+ rc = sigp_retry(cpu->addr, SIGP_RESTART, 0, NULL);
+ if (!rc)
+ cpu->active = true;
+
+out:
+ spin_unlock(&lock);
+ return rc;
+}
+
+/*
+ * Disregarding state, stop all cpus that once were online except for
+ * calling cpu.
+ */
+void smp_teardown(void)
+{
+ int i = 0;
+ uint16_t this_cpu = stap();
+ struct ReadCpuInfo *info = (void *)cpu_info_buffer;
+
+ spin_lock(&lock);
+ for (; i < info->nr_configured; i++) {
+ if (cpus[i].active &&
+ cpus[i].addr != this_cpu) {
+ sigp_retry(cpus[i].addr, SIGP_STOP, 0, NULL);
+ }
+ }
+ spin_unlock(&lock);
+}
+
+/*Expected to be called from boot cpu */
+extern uint64_t *stackptr;
+void smp_setup(void)
+{
+ int i = 0;
+ unsigned short cpu0_addr = stap();
+ struct ReadCpuInfo *info = (void *)cpu_info_buffer;
+
+ spin_lock(&lock);
+ sclp_mark_busy();
+ info->h.length = PAGE_SIZE;
+ sclp_service_call(SCLP_READ_CPU_INFO, cpu_info_buffer);
+
+ if (smp_query_num_cpus() > 1)
+ printf("SMP: Initializing, found %d cpus\n", info->nr_configured);
+
+ cpus = calloc(info->nr_configured, sizeof(cpus));
+ for (i = 0; i < info->nr_configured; i++) {
+ cpus[i].addr = info->entries[i].address;
+ cpus[i].active = false;
+ if (info->entries[i].address == cpu0_addr) {
+ cpu0 = &cpus[i];
+ cpu0->stack = stackptr;
+ cpu0->lowcore = (void *)0;
+ cpu0->active = true;
+ }
+ }
+ spin_unlock(&lock);
+}
diff --git a/lib/s390x/smp.h b/lib/s390x/smp.h
new file mode 100644
index 0000000..4476c31
--- /dev/null
+++ b/lib/s390x/smp.h
@@ -0,0 +1,51 @@
+/*
+ * s390x smp
+ *
+ * Copyright (c) 2019 IBM Corp
+ *
+ * Authors:
+ * Janosch Frank <frankja@linux.ibm.com>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2.
+ */
+#ifndef SMP_H
+#define SMP_H
+
+struct cpu {
+ struct lowcore *lowcore;
+ uint64_t *stack;
+ uint16_t addr;
+ bool active;
+};
+
+struct cpu_status {
+ uint64_t fprs[16]; /* 0x0000 */
+ uint64_t grs[16]; /* 0x0080 */
+ struct psw psw; /* 0x0100 */
+ uint8_t pad_0x0110[0x0118 - 0x0110]; /* 0x0110 */
+ uint32_t prefix; /* 0x0118 */
+ uint32_t fpc; /* 0x011c */
+ uint8_t pad_0x0120[0x0124 - 0x0120]; /* 0x0120 */
+ uint32_t todpr; /* 0x0124 */
+ uint64_t cputm; /* 0x0128 */
+ uint64_t ckc; /* 0x0130 */
+ uint8_t pad_0x0138[0x0140 - 0x0138]; /* 0x0138 */
+ uint32_t ars[16]; /* 0x0140 */
+ uint64_t crs[16]; /* 0x0384 */
+};
+
+int smp_query_num_cpus(void);
+struct cpu *smp_cpu_from_addr(uint16_t addr);
+bool smp_cpu_stopped(uint16_t addr);
+bool smp_cpu_running(uint16_t addr);
+int smp_cpu_restart(uint16_t addr);
+int smp_cpu_start(uint16_t addr, struct psw psw);
+int smp_cpu_stop(uint16_t addr);
+int smp_cpu_stop_store_status(uint16_t addr);
+int smp_cpu_destroy(uint16_t addr);
+int smp_cpu_setup(uint16_t addr, struct psw psw);
+void smp_teardown(void);
+void smp_setup(void);
+
+#endif
diff --git a/s390x/Makefile b/s390x/Makefile
index 96033dd..d83dd0b 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -48,6 +48,7 @@ cflatobjs += lib/s390x/sclp.o
cflatobjs += lib/s390x/sclp-console.o
cflatobjs += lib/s390x/interrupt.o
cflatobjs += lib/s390x/mmu.o
+cflatobjs += lib/s390x/smp.o

OBJDIRS += lib/s390x

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 36f7cab..5dc1577 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -172,6 +172,13 @@ diag308_load_reset:
lhi %r2, 1
br %r14

+.globl smp_cpu_setup_state
+smp_cpu_setup_state:
+ xgr %r1, %r1
+ lmg %r0, %r15, GEN_LC_SW_INT_GRS
+ lctlg %c0, %c0, GEN_LC_SW_INT_CR0
+ br %r14
+
pgm_int:
SAVE_REGS
brasl %r14, handle_pgm_int
--
2.17.2