From: "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx>
Disallow page merging (huge page adjustment) for the mirror root by
utilizing disallowed_hugepage_adjust().
Make the mirror root check asymmetric with NX huge pages and not to litter
the generic MMU code:
Invoke disallowed_hugepage_adjust() in kvm_tdp_mmu_map() when necessary,
specifically when KVM has mirrored TDP or the NX huge page workaround is
enabled.
Check and reduce the goal_level of a fault internally in
disallowed_hugepage_adjust() when the fault is for a mirror root and
there's a shadow present non-leaf entry at the original goal_level.
Signed-off-by: Edgecombe, Rick P <rick.p.edgecombe@xxxxxxxxx>
Co-developed-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
---
RFC v2:
- Check is_mirror_sp() in disallowed_hugepage_adjust() instead of passing
in an is_mirror arg. (Rick)
- Check kvm_has_mirrored_tdp() in kvm_tdp_mmu_map() to determine whether
to invoke disallowed_hugepage_adjust(). (Rick)
RFC v1:
- new patch
---
arch/x86/kvm/mmu/mmu.c | 3 ++-
arch/x86/kvm/mmu/tdp_mmu.c | 4 +++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3f76415cec71..9182192daa3a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3412,7 +3412,8 @@ void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_
cur_level == fault->goal_level &&
is_shadow_present_pte(spte) &&
!is_large_pte(spte) &&
- spte_to_child_sp(spte)->nx_huge_page_disallowed) {
+ ((spte_to_child_sp(spte)->nx_huge_page_disallowed) ||
+ is_mirror_sp(spte_to_child_sp(spte)))) {
/*
* A small SPTE exists for this pfn, but FNAME(fetch),
* direct_map(), or kvm_tdp_mmu_map() would like to create a
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index bb95c95f6531..f9a054754544 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1243,6 +1243,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
struct tdp_iter iter;
struct kvm_mmu_page *sp;
int ret = RET_PF_RETRY;
+ bool hugepage_adjust_disallowed = fault->nx_huge_page_workaround_enabled ||
+ kvm_has_mirrored_tdp(kvm);
kvm_mmu_hugepage_adjust(vcpu, fault);
@@ -1253,7 +1255,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
for_each_tdp_pte(iter, kvm, root, fault->gfn, fault->gfn + 1) {
int r;
- if (fault->nx_huge_page_workaround_enabled)
+ if (hugepage_adjust_disallowed)
disallowed_hugepage_adjust(fault, iter.old_spte, iter.level);
/*
--
2.43.2
