[PATCH v4 14/14] KVM: s390: pv: avoid export before import if possible

From: Claudio Imbrenda <imbrenda@linux.ibm.com>
To: kvm@vger.kernel.org
Cc: cohuck@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com,
	thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ulrich.Weigand@de.ibm.com
Subject: [PATCH v4 14/14] KVM: s390: pv: avoid export before import if possible
Date: Wed, 18 Aug 2021 15:26:20 +0200	[thread overview]
Message-ID: <20210818132620.46770-15-imbrenda@linux.ibm.com> (raw)
In-Reply-To: <20210818132620.46770-1-imbrenda@linux.ibm.com>

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 bc79085d7152..6f8aef5609c0 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -251,7 +251,8 @@ 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

