On Mon, 4 Dec 2017 21:35:23 +0100 Christoffer Dall <cdall@xxxxxxxxxx> wrote: > From: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > > As we're about to call vcpu_load() from architecture-specific > implementations of the KVM vcpu ioctls, but yet we access data > structures protected by the vcpu->mutex in the generic code, factor > this logic out from vcpu_load(). > > x86 is the only architecture which calls vcpu_load() outside of the main > vcpu ioctl function, and these calls will no longer take the vcpu mutex > following this patch. However, with the exception of > kvm_arch_vcpu_postcreate (see below), the callers are either in the > creation or destruction path of the VCPU, which means there cannot be > any concurrent access to the data structure, because the file descriptor > is not yet accessible, or is already gone. > > kvm_arch_vcpu_postcreate makes the newly created vcpu potentially > accessible by other in-kernel threads through the kvm->vcpus array, and > we therefore take the vcpu mutex in this case directly. > > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > --- > arch/x86/kvm/vmx.c | 4 +--- > arch/x86/kvm/x86.c | 20 +++++++------------- > include/linux/kvm_host.h | 2 +- > virt/kvm/kvm_main.c | 17 ++++++----------- > 4 files changed, 15 insertions(+), 28 deletions(-) Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
