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KVM: make processes waiting on vcpu mutex killable

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vcpu mutex can be held for unlimited time so
taking it with mutex_lock on an ioctl is wrong:
one process could be passed a vcpu fd and
call this ioctl on the vcpu used by another process,
it will then be unkillable until the owner exits.

Call mutex_lock_killable instead and return status.
Note: mutex_lock_interruptible would be even nicer,
but I am not sure all users are prepared to handle EINTR
from these ioctls. They might misinterpret it as an error.

Cleanup paths expect a vcpu that can't be used by
any userspace so this will always succeed - catch bugs
by calling BUG_ON.

Catch callers that don't check return state by adding
__must_check.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Michael S. Tsirkin
2012-09-16 11:50:30 +03:00
committed by Marcelo Tosatti
parent 7454766f7b
commit 9fc77441e5
3 changed files with 17 additions and 7 deletions
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12
arch/x86/kvm/x86.c
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@@ -6016,7 +6016,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
int r;
vcpu->arch.mtrr_state.have_fixed = 1;
vcpu_load(vcpu);
r = vcpu_load(vcpu);
if (r)
return r;
r = kvm_arch_vcpu_reset(vcpu);
if (r == 0)
r = kvm_mmu_setup(vcpu);
@@ -6027,9 +6029,11 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
int r;
vcpu->arch.apf.msr_val = 0;
vcpu_load(vcpu);
r = vcpu_load(vcpu);
BUG_ON(r);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
@@ -6275,7 +6279,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
{
vcpu_load(vcpu);
int r;
r = vcpu_load(vcpu);
BUG_ON(r);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
}