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Subject[PATCH 38/40] KVM: Reduce stack usage in kvm_vcpu_ioctl()
Date
From: Dave Hansen <dave@linux.vnet.ibm.com>

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
virt/kvm/kvm_main.c | 46 ++++++++++++++++++++++++++++------------------
1 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5eb96c7..0309571 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1126,6 +1126,8 @@ static long kvm_vcpu_ioctl(struct file *filp,
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
int r;
+ struct kvm_fpu *fpu = NULL;
+ struct kvm_sregs *kvm_sregs = NULL;

if (vcpu->kvm->mm != current->mm)
return -EIO;
@@ -1173,25 +1175,28 @@ out_free2:
break;
}
case KVM_GET_SREGS: {
- struct kvm_sregs kvm_sregs;
-
- memset(&kvm_sregs, 0, sizeof kvm_sregs);
- r = kvm_arch_vcpu_ioctl_get_sregs(vcpu, &kvm_sregs);
+ kvm_sregs = kzalloc(sizeof(struct kvm_sregs), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!kvm_sregs)
+ goto out;
+ r = kvm_arch_vcpu_ioctl_get_sregs(vcpu, kvm_sregs);
if (r)
goto out;
r = -EFAULT;
- if (copy_to_user(argp, &kvm_sregs, sizeof kvm_sregs))
+ if (copy_to_user(argp, kvm_sregs, sizeof(struct kvm_sregs)))
goto out;
r = 0;
break;
}
case KVM_SET_SREGS: {
- struct kvm_sregs kvm_sregs;
-
+ kvm_sregs = kmalloc(sizeof(struct kvm_sregs), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!kvm_sregs)
+ goto out;
r = -EFAULT;
- if (copy_from_user(&kvm_sregs, argp, sizeof kvm_sregs))
+ if (copy_from_user(kvm_sregs, argp, sizeof(struct kvm_sregs)))
goto out;
- r = kvm_arch_vcpu_ioctl_set_sregs(vcpu, &kvm_sregs);
+ r = kvm_arch_vcpu_ioctl_set_sregs(vcpu, kvm_sregs);
if (r)
goto out;
r = 0;
@@ -1272,25 +1277,28 @@ out_free2:
break;
}
case KVM_GET_FPU: {
- struct kvm_fpu fpu;
-
- memset(&fpu, 0, sizeof fpu);
- r = kvm_arch_vcpu_ioctl_get_fpu(vcpu, &fpu);
+ fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!fpu)
+ goto out;
+ r = kvm_arch_vcpu_ioctl_get_fpu(vcpu, fpu);
if (r)
goto out;
r = -EFAULT;
- if (copy_to_user(argp, &fpu, sizeof fpu))
+ if (copy_to_user(argp, fpu, sizeof(struct kvm_fpu)))
goto out;
r = 0;
break;
}
case KVM_SET_FPU: {
- struct kvm_fpu fpu;
-
+ fpu = kmalloc(sizeof(struct kvm_fpu), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!fpu)
+ goto out;
r = -EFAULT;
- if (copy_from_user(&fpu, argp, sizeof fpu))
+ if (copy_from_user(fpu, argp, sizeof(struct kvm_fpu)))
goto out;
- r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, &fpu);
+ r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
if (r)
goto out;
r = 0;
@@ -1300,6 +1308,8 @@ out_free2:
r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
}
out:
+ kfree(fpu);
+ kfree(kvm_sregs);
return r;
}

--
1.6.0.1


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