From 0e587aa7335588ac5e12ef707f7979ff91b11751 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 26 Feb 2022 00:15:28 +0000 Subject: KVM: x86/mmu: Add helpers to read/write TDP MMU SPTEs and document RCU Add helpers to read and write TDP MMU SPTEs instead of open coding rcu_dereference() all over the place, and to provide a convenient location to document why KVM doesn't exempt holding mmu_lock for write from having to hold RCU (and any future changes to the rules). No functional change intended. Signed-off-by: Sean Christopherson Reviewed-by: Ben Gardon Message-Id: <20220226001546.360188-11-seanjc@google.com> Reviewed-by: Mingwei Zhang Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_iter.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/mmu/tdp_iter.c') diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c index be3f096db2eb..6d3b3e5a5533 100644 --- a/arch/x86/kvm/mmu/tdp_iter.c +++ b/arch/x86/kvm/mmu/tdp_iter.c @@ -12,7 +12,7 @@ static void tdp_iter_refresh_sptep(struct tdp_iter *iter) { iter->sptep = iter->pt_path[iter->level - 1] + SHADOW_PT_INDEX(iter->gfn << PAGE_SHIFT, iter->level); - iter->old_spte = READ_ONCE(*rcu_dereference(iter->sptep)); + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); } static gfn_t round_gfn_for_level(gfn_t gfn, int level) @@ -89,7 +89,7 @@ static bool try_step_down(struct tdp_iter *iter) * Reread the SPTE before stepping down to avoid traversing into page * tables that are no longer linked from this entry. */ - iter->old_spte = READ_ONCE(*rcu_dereference(iter->sptep)); + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); child_pt = spte_to_child_pt(iter->old_spte, iter->level); if (!child_pt) @@ -123,7 +123,7 @@ static bool try_step_side(struct tdp_iter *iter) iter->gfn += KVM_PAGES_PER_HPAGE(iter->level); iter->next_last_level_gfn = iter->gfn; iter->sptep++; - iter->old_spte = READ_ONCE(*rcu_dereference(iter->sptep)); + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); return true; } -- cgit v1.2.3