Factor out the logic to atomically replace an SPTE with an SPTE that
points to a new page table. This will be used in a follow-up commit to
split a large page SPTE into one level lower.
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 53 ++++++++++++++++++++++++++------------
1 file changed, 37 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index cc9fe33c9b36..9ee3f4f7fdf5 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -945,6 +945,39 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
return ret;
}
+/*
+ * tdp_mmu_install_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: True if the new page table was installed. False if spte being
+ * replaced changed, causing the atomic compare-exchange to fail.
+ * If this function returns false the sp will be freed before
+ * returning.
+ */
+static bool tdp_mmu_install_sp_atomic(struct kvm *kvm,
+ struct tdp_iter *iter,
+ struct kvm_mmu_page *sp,
+ bool account_nx)
+{
+ u64 spte;
+
+ spte = make_nonleaf_spte(sp->spt, !shadow_accessed_mask);
+
+ if (tdp_mmu_set_spte_atomic(kvm, iter, spte)) {
+ tdp_mmu_link_page(kvm, sp, account_nx);
+ return true;
+ } else {
+ tdp_mmu_free_sp(sp);
+ return false;
+ }
+}
+
/*
* Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
* page tables and SPTEs to translate the faulting guest physical address.
@@ -954,8 +987,6 @@ 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);
@@ -983,6 +1014,9 @@ 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
@@ -992,21 +1026,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
break;
sp = alloc_tdp_mmu_page(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_page(vcpu->kvm, sp,
- fault->huge_page_disallowed &&
- fault->req_level >= iter.level);
-
- trace_kvm_mmu_get_page(sp, true);
- } else {
- tdp_mmu_free_sp(sp);
+ if (!tdp_mmu_install_sp_atomic(vcpu->kvm, &iter, sp, account_nx))
break;
- }
}
}
--
2.34.0.rc2.393.gf8c9666880-goog
