Tested-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
On Fri, Mar 10, 2023 at 04:22:54PM -0800, Sean Christopherson wrote:
> When adding/removing gfns to/from write-tracking, assert that mmu_lock
> is held for write, and that either slots_lock or kvm->srcu is held.
> mmu_lock must be held for write to protect gfn_write_track's refcount,
> and SRCU or slots_lock must be held to protect the memslot itself.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/page_track.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
> index 1993db4578e5..ffcd7ac66f9e 100644
> --- a/arch/x86/kvm/mmu/page_track.c
> +++ b/arch/x86/kvm/mmu/page_track.c
> @@ -12,6 +12,7 @@
> */
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> +#include <linux/lockdep.h>
> #include <linux/kvm_host.h>
> #include <linux/rculist.h>
>
> @@ -77,9 +78,6 @@ static void update_gfn_write_track(struct kvm_memory_slot *slot, gfn_t gfn,
> * add guest page to the tracking pool so that corresponding access on that
> * page will be intercepted.
> *
> - * It should be called under the protection both of mmu-lock and kvm->srcu
> - * or kvm->slots_lock.
> - *
> * @kvm: the guest instance we are interested in.
> * @slot: the @gfn belongs to.
> * @gfn: the guest page.
> @@ -87,6 +85,11 @@ static void update_gfn_write_track(struct kvm_memory_slot *slot, gfn_t gfn,
> void kvm_write_track_add_gfn(struct kvm *kvm, struct kvm_memory_slot *slot,
> gfn_t gfn)
> {
> + lockdep_assert_held_write(&kvm->mmu_lock);
> +
> + lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
> + srcu_read_lock_held(&kvm->srcu));
> +
> if (WARN_ON(!kvm_page_track_write_tracking_enabled(kvm)))
> return;
>
> @@ -107,9 +110,6 @@ EXPORT_SYMBOL_GPL(kvm_write_track_add_gfn);
> * remove the guest page from the tracking pool which stops the interception
> * of corresponding access on that page.
> *
> - * It should be called under the protection both of mmu-lock and kvm->srcu
> - * or kvm->slots_lock.
> - *
> * @kvm: the guest instance we are interested in.
> * @slot: the @gfn belongs to.
> * @gfn: the guest page.
> @@ -117,6 +117,11 @@ EXPORT_SYMBOL_GPL(kvm_write_track_add_gfn);
> void kvm_write_track_remove_gfn(struct kvm *kvm,
> struct kvm_memory_slot *slot, gfn_t gfn)
> {
> + lockdep_assert_held_write(&kvm->mmu_lock);
> +
> + lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
> + srcu_read_lock_held(&kvm->srcu));
> +
> if (WARN_ON(!kvm_page_track_write_tracking_enabled(kvm)))
> return;
>
> --
> 2.40.0.rc1.284.g88254d51c5-goog
>
