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-rw-r--r--arch/s390/kvm/priv.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 3916263..d026389 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -336,6 +336,7 @@ static int handle_tprot(struct kvm_vcpu *vcpu)
u64 address1 = disp1 + base1 ? vcpu->arch.guest_gprs[base1] : 0;
u64 address2 = disp2 + base2 ? vcpu->arch.guest_gprs[base2] : 0;
struct vm_area_struct *vma;
+ unsigned long user_address;
vcpu->stat.instruction_tprot++;
@@ -349,9 +350,14 @@ static int handle_tprot(struct kvm_vcpu *vcpu)
return -EOPNOTSUPP;
+ /* we must resolve the address without holding the mmap semaphore.
+ * This is ok since the userspace hypervisor is not supposed to change
+ * the mapping while the guest queries the memory. Otherwise the guest
+ * might crash or get wrong info anyway. */
+ user_address = (unsigned long) __guestaddr_to_user(vcpu, address1);
+
down_read(&current->mm->mmap_sem);
- vma = find_vma(current->mm,
- (unsigned long) __guestaddr_to_user(vcpu, address1));
+ vma = find_vma(current->mm, user_address);
if (!vma) {
up_read(&current->mm->mmap_sem);
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
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