[PATCH] kvm: fix GFP_KERNEL allocation in atomic section in kvm_dev_ioctl_create_vcpu()

fix an GFP_KERNEL allocation in atomic section: kvm_dev_ioctl_create_vcpu()
called kvm_mmu_init(), which calls alloc_pages(), while holding the vcpu.

The fix is to set up the MMU state in two phases: kvm_mmu_create() and
kvm_mmu_setup().

(NOTE: free_vcpus does an kvm_mmu_destroy() call so there's no need for any
extra teardown branch on allocation/init failure here.)

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

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 2670219..100df6f 100644 (file)
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -319,7 +319,8 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module);
 void kvm_exit_arch(void);
 
 void kvm_mmu_destroy(struct kvm_vcpu *vcpu);
-int kvm_mmu_init(struct kvm_vcpu *vcpu);
+int kvm_mmu_create(struct kvm_vcpu *vcpu);
+int kvm_mmu_setup(struct kvm_vcpu *vcpu);
 
 int kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot);

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 9735445..ce7fe64 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -522,12 +522,14 @@ static int kvm_dev_ioctl_create_vcpu(struct kvm *kvm, int n)
        if (r < 0)
                goto out_free_vcpus;
 
-       kvm_arch_ops->vcpu_load(vcpu);
+       r = kvm_mmu_create(vcpu);
+       if (r < 0)
+               goto out_free_vcpus;
 
-       r = kvm_arch_ops->vcpu_setup(vcpu);
+       kvm_arch_ops->vcpu_load(vcpu);
+       r = kvm_mmu_setup(vcpu);
        if (r >= 0)
-               r = kvm_mmu_init(vcpu);
-
+               r = kvm_arch_ops->vcpu_setup(vcpu);
        vcpu_put(vcpu);
 
        if (r < 0)

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 85887fc..790423c 100644 (file)
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -639,28 +639,22 @@ error_1:
        return -ENOMEM;
 }
 
-int kvm_mmu_init(struct kvm_vcpu *vcpu)
+int kvm_mmu_create(struct kvm_vcpu *vcpu)
 {
-       int r;
-
        ASSERT(vcpu);
        ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
        ASSERT(list_empty(&vcpu->free_pages));
 
-       r = alloc_mmu_pages(vcpu);
-       if (r)
-               goto out;
-
-       r = init_kvm_mmu(vcpu);
-       if (r)
-               goto out_free_pages;
+       return alloc_mmu_pages(vcpu);
+}
 
-       return 0;
+int kvm_mmu_setup(struct kvm_vcpu *vcpu)
+{
+       ASSERT(vcpu);
+       ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
+       ASSERT(!list_empty(&vcpu->free_pages));
 
-out_free_pages:
-       free_mmu_pages(vcpu);
-out:
-       return r;
+       return init_kvm_mmu(vcpu);
 }
 
 void kvm_mmu_destroy(struct kvm_vcpu *vcpu)