[PATCH 15/40] KVM: Disable pagefaults during copy_from_user_inatomic()

[Avi Kivity]

From: Andrea Arcangeli <andrea@xxxxxxxxxxxx>

With CONFIG_PREEMPT=n, this is needed in order to disable the fault-in
code from sleeping.

Signed-off-by: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
 virt/kvm/kvm_main.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7972e3a..cf6df51 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -554,7 +554,9 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
 	addr = gfn_to_hva(kvm, gfn);
 	if (kvm_is_error_hva(addr))
 		return -EFAULT;
+	pagefault_disable();
 	r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
+	pagefault_enable();
 	if (r)
 		return -EFAULT;
 	return 0;
-- 
1.5.4.5

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