linux-kernel - [PATCH 5.9 076/152] KVM: s390: pv: Mark mm as protected after the set secure parameters and improve cleanup

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Date:   Tue,  1 Dec 2020 09:53:11 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Janosch Frank <frankja@...ux.ibm.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 076/152] KVM: s390: pv: Mark mm as protected after the set secure parameters and improve cleanup

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

[ Upstream commit 1ed576a20cd5c93295f57d6b7400357bd8d01b21 ]

We can only have protected guest pages after a successful set secure
parameters call as only then the UV allows imports and unpacks.

By moving the test we can now also check for it in s390_reset_acc()
and do an early return if it is 0.

Signed-off-by: Janosch Frank <frankja@...ux.ibm.com>
Fixes: 29b40f105ec8 ("KVM: s390: protvirt: Add initial vm and cpu lifecycle handling")
Reviewed-by: Cornelia Huck <cohuck@...hat.com>
Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/s390/kvm/kvm-s390.c | 2 +-
 arch/s390/kvm/pv.c       | 3 ++-
 arch/s390/mm/gmap.c      | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6b74b92c1a586..08ea6c4735cdc 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2312,7 +2312,7 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 		struct kvm_s390_pv_unp unp = {};
 
 		r = -EINVAL;
-		if (!kvm_s390_pv_is_protected(kvm))
+		if (!kvm_s390_pv_is_protected(kvm) || !mm_is_protected(kvm->mm))
 			break;
 
 		r = -EFAULT;
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index eb99e2f95ebed..f5847f9dec7c9 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -208,7 +208,6 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 		return -EIO;
 	}
 	kvm->arch.gmap->guest_handle = uvcb.guest_handle;
-	atomic_set(&kvm->mm->context.is_protected, 1);
 	return 0;
 }
 
@@ -228,6 +227,8 @@ int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
 	*rrc = uvcb.header.rrc;
 	KVM_UV_EVENT(kvm, 3, "PROTVIRT VM SET PARMS: rc %x rrc %x",
 		     *rc, *rrc);
+	if (!cc)
+		atomic_set(&kvm->mm->context.is_protected, 1);
 	return cc ? -EINVAL : 0;
 }
 
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 373542ca1113e..78dbba6a4500c 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2690,6 +2690,8 @@ static const struct mm_walk_ops reset_acc_walk_ops = {
 #include <linux/sched/mm.h>
 void s390_reset_acc(struct mm_struct *mm)
 {
+	if (!mm_is_protected(mm))
+		return;
 	/*
 	 * we might be called during
 	 * reset:                             we walk the pages and clear
-- 
2.27.0