On Tue, Aug 10, 2021 at 3:46 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Drop @shared from tdp_mmu_link_page() and hardcode it to work for
> mmu_lock being held for read. The helper has exactly one caller and
> in all likelihood will only ever have exactly one caller. Even if KVM
> adds a path to install translations without an initiating page fault,
> odds are very, very good that the path will just be a wrapper to the
> "page fault" handler (both SNP and TDX RFCs propose patches to do
> exactly that).
>
> No functional change intended.
>
> Cc: Ben Gardon <bgardon@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
Nice cleanup!
> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index d99e064d366f..c5b901744d15 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -257,26 +257,17 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
> *
> * @kvm: kvm instance
> * @sp: the new page
> - * @shared: This operation may not be running under the exclusive use of
> - * the MMU lock and the operation must synchronize with other
> - * threads that might be adding or removing pages.
> * @account_nx: This page replaces a NX large page and should be marked for
> * eventual reclaim.
> */
> static void tdp_mmu_link_page(struct kvm *kvm, struct kvm_mmu_page *sp,
> - bool shared, bool account_nx)
> + bool account_nx)
> {
> - if (shared)
> - spin_lock(&kvm->arch.tdp_mmu_pages_lock);
> - else
> - lockdep_assert_held_write(&kvm->mmu_lock);
> -
> + spin_lock(&kvm->arch.tdp_mmu_pages_lock);
> list_add(&sp->link, &kvm->arch.tdp_mmu_pages);
> if (account_nx)
> account_huge_nx_page(kvm, sp);
> -
> - if (shared)
> - spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
> + spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
> }
>
> /**
> @@ -1062,7 +1053,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
> !shadow_accessed_mask);
>
> if (tdp_mmu_set_spte_atomic_no_dirty_log(vcpu->kvm, &iter, new_spte)) {
> - tdp_mmu_link_page(vcpu->kvm, sp, true,
> + tdp_mmu_link_page(vcpu->kvm, sp,
> huge_page_disallowed &&
> req_level >= iter.level);
>
> --
> 2.32.0.605.g8dce9f2422-goog
>
