[PATCH v4 12/28] KVM: TDX: WARN if mirror SPTE doesn't have full RWX when creating S-EPT mapping
From: Sean Christopherson <seanjc@google.com>
Date: 2025-10-30 20:10:28
Also in:
kvm, kvm-riscv, kvmarm, linux-coco, linux-mips, linux-riscv, linuxppc-dev, lkml, loongarch
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Pass in the mirror_spte to kvm_x86_ops.set_external_spte() to provide symmetry with .remove_external_spte(), and assert in TDX that the mirror SPTE is shadow-present with full RWX permissions (the TDX-Module doesn't allow the hypervisor to control protections). Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/mmu/tdp_mmu.c | 3 +-- arch/x86/kvm/vmx/tdx.c | 6 +++++- 3 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b5867f8fe6ce..87a5f5100b1d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -1848,7 +1848,7 @@ struct kvm_x86_ops { void *external_spt); /* Update the external page table from spte getting set. */ int (*set_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level, - kvm_pfn_t pfn_for_gfn); + u64 mirror_spte); /* Update external page tables for page table about to be freed. */ int (*free_external_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index e1a96e9ea1bb..9c26038f6b77 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c@@ -515,7 +515,6 @@ static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sp bool was_present = is_shadow_present_pte(old_spte); bool is_present = is_shadow_present_pte(new_spte); bool is_leaf = is_present && is_last_spte(new_spte, level); - kvm_pfn_t new_pfn = spte_to_pfn(new_spte); int ret = 0; KVM_BUG_ON(was_present, kvm);
@@ -534,7 +533,7 @@ static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sp * external page table, or leaf. */ if (is_leaf) { - ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_pfn); + ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_spte); } else { void *external_spt = get_external_spt(gfn, new_spte, level);
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 7ab67ad83677..658e0407eb21 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c@@ -1629,14 +1629,18 @@ static int tdx_mem_page_record_premap_cnt(struct kvm *kvm, gfn_t gfn, } static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, - enum pg_level level, kvm_pfn_t pfn) + enum pg_level level, u64 mirror_spte) { struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); + kvm_pfn_t pfn = spte_to_pfn(mirror_spte); /* TODO: handle large pages. */ if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm)) return -EIO; + WARN_ON_ONCE(!is_shadow_present_pte(mirror_spte) || + (mirror_spte & VMX_EPT_RWX_MASK) != VMX_EPT_RWX_MASK); + /* * Read 'pre_fault_allowed' before 'kvm_tdx->state'; see matching * barrier in tdx_td_finalize().
--
2.51.1.930.gacf6e81ea2-goog