[PATCH] kvm: s390: pv: Mark mm as protected after the set secure parameters and improve cleanup

Janosch Frank
2020-10-30T14:01:56Z

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@linux.ibm.com>
---
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 6b74b92c1a58..08ea6c4735cd 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 eb99e2f95ebe..f5847f9dec7c 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 cfb0017f33a7..64795d034926 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
--
2.25.1