[kvm-unit-tests PATCH 5/8] s390x: uv-host: Explain why we set up the home space and remove the space change

[Janosch Frank <frankja@linux.ibm.com>]

UV home addresses don't require us to be in home space but we need to
have it set up so hw/fw can use the home asce to translate home
virtual addresses.

Hence we add a comment why we're setting up the home asce and remove
the address space since it's unneeded.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 s390x/uv-host.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/s390x/uv-host.c b/s390x/uv-host.c
index 426a67f6..28035707 100644
--- a/s390x/uv-host.c
+++ b/s390x/uv-host.c
@@ -444,13 +444,18 @@ static void test_clear(void)
 
 static void setup_vmem(void)
 {
-	uint64_t asce, mask;
+	uint64_t asce;
 
 	setup_mmu(get_max_ram_size(), NULL);
+	/*
+	 * setup_mmu() will enable DAT and set the primary address
+	 * space but we need to have a valid home space since UV calls
+	 * take home space virtual addresses.
+	 *
+	 * Hence we just copy the primary asce into the home space.
+	 */
 	asce = stctg(1);
 	lctlg(13, asce);
-	mask = extract_psw_mask() | 0x0000C00000000000UL;
-	load_psw_mask(mask);
 }
 
 int main(void)
-- 
2.30.2