[kvm-unit-tests PATCH] riscv: Make NR_CPUS configurable

Andrew Jones
2024-08-20T17:01:54Z

Unit tests would like to go nuts with the number of harts in order
to help shake out issues with hart number assumptions. Rather than
set a huge number that will only be used when a platform supports
a huge number or when QEMU is told to exceed the recommended
number of vcpus, make the number configurable. However, we do bump
the default from 16 to 2*xlen since we would like to always force
kvm-unit-tests to use cpumasks with more than one word in order to
ensure that code stays maintained.

Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
---
configure | 8 ++++++++
lib/riscv/asm/setup.h | 3 ++-
2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 27ae9cc89657..6a8d6239a3cb 100755
--- a/configure
+++ b/configure
@@ -77,6 +77,8 @@ usage() {
Specify the page size (translation granule). PAGE_SIZE can be
4k [default], 16k, 64k for arm64.
4k [default], 64k for ppc64.
+ --max-cpus=MAX_CPUS
+ Specify the maximum number of CPUs supported. (riscv64 only)
--earlycon=EARLYCON
Specify the UART name, type and address (optional, arm and
arm64 only). The specified address will overwrite the UART
@@ -168,6 +170,9 @@ while [[ "$1" = -* ]]; do
--page-size)
page_size="$arg"
;;
+ --max-cpus)
+ max_cpus="$arg"
+ ;;
--earlycon)
earlycon="$arg"
;;
@@ -496,8 +501,11 @@ cat <<EOF >> lib/config.h

EOF
elif [ "$arch" = "riscv32" ] || [ "$arch" = "riscv64" ]; then
+ [ -z $max_cpus ] && max_cpus='(__riscv_xlen * 2)'
+
cat <<EOF >> lib/config.h

+#define CONFIG_NR_CPUS $max_cpus
#define CONFIG_UART_EARLY_BASE 0x10000000

EOF
diff --git a/lib/riscv/asm/setup.h b/lib/riscv/asm/setup.h
index a13159bfe395..43b63c56d96f 100644
--- a/lib/riscv/asm/setup.h
+++ b/lib/riscv/asm/setup.h
@@ -2,9 +2,10 @@
#ifndef _ASMRISCV_SETUP_H_
#define _ASMRISCV_SETUP_H_
#include <libcflat.h>
+#include <config.h>
#include <asm/processor.h>

-#define NR_CPUS 16
+#define NR_CPUS CONFIG_NR_CPUS
extern struct thread_info cpus[NR_CPUS];
extern int nr_cpus;
extern uint64_t timebase_frequency;
--
2.45.2