Consolidate the logic to atomically replace an SPTE with an SPTE that
points to a new page table into a single helper function. This will be
used in a follow-up commit to split huge pages, which involves replacing
each huge page SPTE with an SPTE that points to a page table.
Opportunistically drop the call to trace_kvm_mmu_get_page() in
kvm_tdp_mmu_map() since it is redundant with the identical tracepoint in
tdp_mmu_alloc_sp().
No functional change intended.
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 68 ++++++++++++++++++++------------------
1 file changed, 36 insertions(+), 32 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 902dd6e49e50..f6144db48367 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -251,24 +251,6 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
}
}
-/**
- * tdp_mmu_link_sp() - Add a new shadow page to the list of used pages
- *
- * @kvm: kvm instance
- * @sp: the new page
- * @account_nx: This page replaces a NX large page and should be marked for
- * eventual reclaim.
- */
-static void tdp_mmu_link_sp(struct kvm *kvm, struct kvm_mmu_page *sp,
- bool account_nx)
-{
- 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);
- spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
-}
-
/**
* tdp_mmu_unlink_sp() - Remove a shadow page from the list of used pages
*
@@ -959,6 +941,38 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
return ret;
}
+/*
+ * tdp_mmu_link_sp_atomic - Atomically replace the given spte with an spte
+ * pointing to the provided page table.
+ *
+ * @kvm: kvm instance
+ * @iter: a tdp_iter instance currently on the SPTE that should be set
+ * @sp: The new TDP page table to install.
+ * @account_nx: True if this page table is being installed to split a
+ * non-executable huge page.
+ *
+ * Returns: 0 if the new page table was installed. Non-0 if the page table
+ * could not be installed (e.g. the atomic compare-exchange failed).
+ */
+static int tdp_mmu_link_sp_atomic(struct kvm *kvm, struct tdp_iter *iter,
+ struct kvm_mmu_page *sp, bool account_nx)
+{
+ u64 spte = make_nonleaf_spte(sp->spt, !shadow_accessed_mask);
+ int ret;
+
+ ret = tdp_mmu_set_spte_atomic(kvm, iter, spte);
+ if (ret)
+ return ret;
+
+ 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);
+ spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
+
+ return 0;
+}
+
/*
* Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
* page tables and SPTEs to translate the faulting guest physical address.
@@ -968,8 +982,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
struct kvm_mmu *mmu = vcpu->arch.mmu;
struct tdp_iter iter;
struct kvm_mmu_page *sp;
- u64 *child_pt;
- u64 new_spte;
int ret;
kvm_mmu_hugepage_adjust(vcpu, fault);
@@ -1004,6 +1016,9 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
}
if (!is_shadow_present_pte(iter.old_spte)) {
+ bool account_nx = fault->huge_page_disallowed &&
+ fault->req_level >= iter.level;
+
/*
* If SPTE has been frozen by another thread, just
* give up and retry, avoiding unnecessary page table
@@ -1013,18 +1028,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
break;
sp = tdp_mmu_alloc_sp(vcpu, iter.gfn, iter.level - 1);
- child_pt = sp->spt;
-
- new_spte = make_nonleaf_spte(child_pt,
- !shadow_accessed_mask);
-
- if (!tdp_mmu_set_spte_atomic(vcpu->kvm, &iter, new_spte)) {
- tdp_mmu_link_sp(vcpu->kvm, sp,
- fault->huge_page_disallowed &&
- fault->req_level >= iter.level);
-
- trace_kvm_mmu_get_page(sp, true);
- } else {
+ if (tdp_mmu_link_sp_atomic(vcpu->kvm, &iter, sp, account_nx)) {
tdp_mmu_free_sp(sp);
break;
}
--
2.35.0.rc0.227.g00780c9af4-goog
