On Thu, Oct 03, 2019 at 08:04:23PM +0300, Jarkko Sakkinen wrote:
> Use mmu_notifier_put() to synchronize sgx_encl_mm deletion.
>
> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
> v2:
> * Was not thinking clearly that we also use it for lockless
> operation on the mm list. Just migrating to mmu_notifier_put().
> Please ignore the previous patch!
> arch/x86/kernel/cpu/sgx/encl.c | 26 ++++++++++----------------
> 1 file changed, 10 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index d145360380d5..8cc9ea353bee 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -131,14 +131,6 @@ static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
> return entry;
> }
>
> -static void sgx_encl_mm_release_deferred(struct rcu_head *rcu)
> -{
> - struct sgx_encl_mm *encl_mm =
> - container_of(rcu, struct sgx_encl_mm, rcu);
> -
> - kfree(encl_mm);
> -}
> -
> static void sgx_mmu_notifier_release(struct mmu_notifier *mn,
> struct mm_struct *mm)
> {
> @@ -161,19 +153,21 @@ static void sgx_mmu_notifier_release(struct mmu_notifier *mn,
>
> if (tmp == encl_mm) {
> synchronize_srcu(&encl_mm->encl->srcu);
> -
> - /*
> - * Delay freeing encl_mm until after mmu_notifier synchronizes
> - * its SRCU to ensure encl_mm cannot be dereferenced.
> - */
> - mmu_notifier_unregister_no_release(mn, mm);
> - mmu_notifier_call_srcu(&encl_mm->rcu,
> - &sgx_encl_mm_release_deferred);
> + mmu_notifier_put(mn);
> }
> }
>
> +static void sgx_mmu_notifier_free(struct mmu_notifier *mn)
> +{
> + struct sgx_encl_mm *encl_mm =
> + container_of(mn, struct sgx_encl_mm, mmu_notifier);
> +
> + kfree(encl_mm);
> +}
> +
> static const struct mmu_notifier_ops sgx_mmu_notifier_ops = {
> .release = sgx_mmu_notifier_release,
> + .free_notifier = sgx_mmu_notifier_free,
> };
>
> static struct sgx_encl_mm *sgx_encl_find_mm(struct sgx_encl *encl,
> --
> 2.20.1
>
This one I squashed (master updated).
/Jarkko
