[PATCH v3 14/14] KVM: s390: pv: avoid export before import if possible

Claudio Imbrenda
2021-08-04T15:41:23Z

If the appropriate UV feature bit is set, there is no need to perform
an export before import.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
arch/s390/kernel/uv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 5b632846c4a4..fa0a51121136 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -298,7 +298,8 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr,

static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm)
{
- return uvcb->cmd != UVC_CMD_UNPIN_PAGE_SHARED &&
+ return !test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
+ uvcb->cmd != UVC_CMD_UNPIN_PAGE_SHARED &&
atomic_read(&mm->context.is_protected) > 1;
}

--
2.31.1