[PATCH] KVM: Fix GFP_KERNEL alloc in atomic section bug

KVM does kmalloc() in an atomic section while having preemption disabled via
vcpu_load().  Fix this by moving the ->*_msr setup from the vcpu_setup method
to the vcpu_create method.

(This is also a small speedup for setting up a vcpu, which can in theory be
more frequent than the vcpu_create method).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 21 insertions, 11 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index d0a2c2d5342a..fbab07af6574 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1094,14 +1094,6 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
         rdmsrl(MSR_IA32_SYSENTER_EIP, a);
         vmcs_writel(HOST_IA32_SYSENTER_EIP, a);   /* 22.2.3 */
 
-        ret = -ENOMEM;
-        vcpu->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
-        if (!vcpu->guest_msrs)
-                goto out;
-        vcpu->host_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
-        if (!vcpu->host_msrs)
-                goto out_free_guest_msrs;
-
         for (i = 0; i < NR_VMX_MSR; ++i) {
                 u32 index = vmx_msr_index[i];
                 u32 data_low, data_high;
@@ -1155,8 +1147,6 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
 
         return 0;
 
-out_free_guest_msrs:
-        kfree(vcpu->guest_msrs);
 out:
         return ret;
 }
@@ -1906,13 +1896,33 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
 {
         struct vmcs *vmcs;
 
+        vcpu->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!vcpu->guest_msrs)
+                return -ENOMEM;
+
+        vcpu->host_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!vcpu->host_msrs)
+                goto out_free_guest_msrs;
+
         vmcs = alloc_vmcs();
         if (!vmcs)
-                return -ENOMEM;
+                goto out_free_msrs;
+
         vmcs_clear(vmcs);
         vcpu->vmcs = vmcs;
         vcpu->launched = 0;
+
         return 0;
+
+out_free_msrs:
+        kfree(vcpu->host_msrs);
+        vcpu->host_msrs = NULL;
+
+out_free_guest_msrs:
+        kfree(vcpu->guest_msrs);
+        vcpu->guest_msrs = NULL;
+
+        return -ENOMEM;
 }
 
 static struct kvm_arch_ops vmx_arch_ops = {