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Date: Wed, 2 Aug 2023 22:27:37 +0800
From: Wei Wang <wei.w.wang@...el.com>
To: seanjc@...gle.com, pbonzini@...hat.com, bgardon@...gle.com,
dmatlack@...gle.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
Wei Wang <wei.w.wang@...el.com>
Subject: [PATCH v1] KVM: x86/mmu: refactor kvm_tdp_mmu_map
The implementation of kvm_tdp_mmu_map is a bit long. It essentially does
three things:
1) adjust the leaf entry level (e.g. 4KB, 2MB or 1GB) to map according to
the hugepage configurations;
2) map the nonleaf entries of the tdp page table; and
3) map the target leaf entry.
Improve the readabiliy by moving the implementation of 2) above into a
subfunction, kvm_tdp_mmu_map_nonleaf, and removing the unnecessary
"goto"s. No functional changes intended.
Signed-off-by: Wei Wang <wei.w.wang@...el.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 76 ++++++++++++++++++++------------------
1 file changed, 41 insertions(+), 35 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 512163d52194..0b29a7f853b5 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1057,43 +1057,33 @@ static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter,
static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
struct kvm_mmu_page *sp, bool shared);
-/*
- * Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
- * page tables and SPTEs to translate the faulting guest physical address.
- */
-int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
+static int kvm_tdp_mmu_map_nonleafs(struct kvm_vcpu *vcpu,
+ struct kvm_page_fault *fault,
+ struct tdp_iter *iter)
{
struct kvm_mmu *mmu = vcpu->arch.mmu;
struct kvm *kvm = vcpu->kvm;
- struct tdp_iter iter;
struct kvm_mmu_page *sp;
- int ret = RET_PF_RETRY;
-
- kvm_mmu_hugepage_adjust(vcpu, fault);
-
- trace_kvm_mmu_spte_requested(fault);
-
- rcu_read_lock();
-
- tdp_mmu_for_each_pte(iter, mmu, fault->gfn, fault->gfn + 1) {
- int r;
+ int ret;
+ tdp_mmu_for_each_pte((*iter), mmu, fault->gfn, fault->gfn + 1) {
if (fault->nx_huge_page_workaround_enabled)
- disallowed_hugepage_adjust(fault, iter.old_spte, iter.level);
+ disallowed_hugepage_adjust(fault, iter->old_spte,
+ iter->level);
/*
* If SPTE has been frozen by another thread, just give up and
* retry, avoiding unnecessary page table allocation and free.
*/
- if (is_removed_spte(iter.old_spte))
- goto retry;
+ if (is_removed_spte(iter->old_spte))
+ return RET_PF_RETRY;
- if (iter.level == fault->goal_level)
- goto map_target_level;
+ if (iter->level == fault->goal_level)
+ return RET_PF_CONTINUE;
/* Step down into the lower level page table if it exists. */
- if (is_shadow_present_pte(iter.old_spte) &&
- !is_large_pte(iter.old_spte))
+ if (is_shadow_present_pte(iter->old_spte) &&
+ !is_large_pte(iter->old_spte))
continue;
/*
@@ -1101,26 +1091,26 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
* needs to be split.
*/
sp = tdp_mmu_alloc_sp(vcpu);
- tdp_mmu_init_child_sp(sp, &iter);
+ tdp_mmu_init_child_sp(sp, iter);
sp->nx_huge_page_disallowed = fault->huge_page_disallowed;
- if (is_shadow_present_pte(iter.old_spte))
- r = tdp_mmu_split_huge_page(kvm, &iter, sp, true);
+ if (is_shadow_present_pte(iter->old_spte))
+ ret = tdp_mmu_split_huge_page(kvm, iter, sp, true);
else
- r = tdp_mmu_link_sp(kvm, &iter, sp, true);
+ ret = tdp_mmu_link_sp(kvm, iter, sp, true);
/*
* Force the guest to retry if installing an upper level SPTE
* failed, e.g. because a different task modified the SPTE.
*/
- if (r) {
+ if (ret) {
tdp_mmu_free_sp(sp);
- goto retry;
+ return RET_PF_RETRY;
}
if (fault->huge_page_disallowed &&
- fault->req_level >= iter.level) {
+ fault->req_level >= iter->level) {
spin_lock(&kvm->arch.tdp_mmu_pages_lock);
if (sp->nx_huge_page_disallowed)
track_possible_nx_huge_page(kvm, sp);
@@ -1132,13 +1122,29 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
* The walk aborted before reaching the target level, e.g. because the
* iterator detected an upper level SPTE was frozen during traversal.
*/
- WARN_ON_ONCE(iter.level == fault->goal_level);
- goto retry;
+ WARN_ON_ONCE(iter->level == fault->goal_level);
+ return RET_PF_RETRY;
+}
-map_target_level:
- ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
+/*
+ * Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
+ * page tables and SPTEs to translate the faulting guest physical address.
+ */
+int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
+{
+ struct tdp_iter iter;
+ int ret;
+
+ kvm_mmu_hugepage_adjust(vcpu, fault);
+
+ trace_kvm_mmu_spte_requested(fault);
+
+ rcu_read_lock();
+
+ ret = kvm_tdp_mmu_map_nonleafs(vcpu, fault, &iter);
+ if (ret == RET_PF_CONTINUE)
+ ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
-retry:
rcu_read_unlock();
return ret;
}
--
2.27.0
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