[kvm-unit-tests GIT PULL 03/26] lib: s390x: hw: rework do_detect_host so we don't need allocation

[Nico Boehr <nrb@linux.ibm.com>]

From: Janosch Frank <frankja@linux.ibm.com>

The current implementation needs to allocate a page for stsi 1.1.1 and
3.2.2. As such it's not usable before the allocator is set
up.

Unfortunately we might end up with detect_host calls before the
allocator setup is done. For example in the SCLP console setup code.

Let's allocate the stsi storage on the stack to solve that problem.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20231031095519.73311-2-frankja@linux.ibm.com
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 lib/s390x/hardware.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/s390x/hardware.c b/lib/s390x/hardware.c
index 2bcf9c4..2175256 100644
--- a/lib/s390x/hardware.c
+++ b/lib/s390x/hardware.c
@@ -13,6 +13,7 @@
 #include <libcflat.h>
 #include <alloc_page.h>
 #include <asm/arch_def.h>
+#include <asm/page.h>
 #include "hardware.h"
 #include "stsi.h"
 
@@ -21,9 +22,10 @@ static const uint8_t qemu_ebcdic[] = { 0xd8, 0xc5, 0xd4, 0xe4 };
 /* The string "KVM/" in EBCDIC */
 static const uint8_t kvm_ebcdic[] = { 0xd2, 0xe5, 0xd4, 0x61 };
 
-static enum s390_host do_detect_host(void *buf)
+static enum s390_host do_detect_host(void)
 {
-	struct sysinfo_3_2_2 *stsi_322 = buf;
+	uint8_t buf[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+	struct sysinfo_3_2_2 *stsi_322 = (struct sysinfo_3_2_2 *)buf;
 
 	if (stsi_get_fc() == 2)
 		return HOST_IS_LPAR;
@@ -56,14 +58,11 @@ enum s390_host detect_host(void)
 {
 	static enum s390_host host = HOST_IS_UNKNOWN;
 	static bool initialized = false;
-	void *buf;
 
 	if (initialized)
 		return host;
 
-	buf = alloc_page();
-	host = do_detect_host(buf);
-	free_page(buf);
+	host = do_detect_host();
 	initialized = true;
 	return host;
 }
-- 
2.41.0