From: Andrea Arcangeli <andrea@qumranet.com>
Date: Wed, 30 Jan 2008 18:57:35 +0000 (+0100)
Subject: KVM: Disable pagefaults during copy_from_user_inatomic()
X-Git-Tag: v2.6.26-rc1~1028^2~132
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0aac03f07b37da96e00371e66973d5ffaae578a4;p=linux-2.6

KVM: Disable pagefaults during copy_from_user_inatomic()

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

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7972e3aa2c..cf6df5167a 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;