Drop kvm_x86_ops.remove_external_spte(), and instead handling the removal of leaf SPTEs in the S-EPT (a.k.a. external root) in .set_private_spte(). This will allow extending tdx_sept_set_private_spte() to support splitting a huge S-EPT entry without needing yet another kvm_x86_ops hook. Bug the VM if the callback fails, as redundant KVM_BUG_ON() calls are benign (the WARN will fire if and only if the VM isn't already bugged) and handle_changed_spte() is most definitely not prepared to handle failure. Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm-x86-ops.h | 1 - arch/x86/include/asm/kvm_host.h | 2 -- arch/x86/kvm/mmu/tdp_mmu.c | 20 +++++++++++--------- arch/x86/kvm/vmx/tdx.c | 21 ++++++++++++--------- 4 files changed, 23 insertions(+), 21 deletions(-) diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index 394dc29483a7..3ca56fe6b951 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -97,7 +97,6 @@ KVM_X86_OP(load_mmu_pgd) KVM_X86_OP_OPTIONAL(alloc_external_sp) KVM_X86_OP_OPTIONAL(free_external_sp) KVM_X86_OP_OPTIONAL_RET0(set_external_spte) -KVM_X86_OP_OPTIONAL(remove_external_spte) KVM_X86_OP_OPTIONAL(reclaim_external_sp) KVM_X86_OP_OPTIONAL_RET0(topup_external_cache) KVM_X86_OP(has_wbinvd_exit) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 67deec8e205e..385f1cf32d70 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1861,8 +1861,6 @@ struct kvm_x86_ops { u64 new_spte, enum pg_level level); void (*reclaim_external_sp)(struct kvm *kvm, gfn_t gfn, struct kvm_mmu_page *sp); - void (*remove_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level, - u64 mirror_spte); int (*topup_external_cache)(struct kvm_vcpu *vcpu, int min); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 271dd6f875a6..d49aecba18d8 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -559,20 +559,22 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep, * SPTE being converted to a hugepage (leaf) or being zapped. Shadow * pages are kernel allocations and should never be migrated. * - * When removing leaf entries from a mirror, immediately propagate the - * changes to the external page tables. Note, non-leaf mirror entries - * are handled by handle_removed_pt(), as TDX requires that all leaf - * entries are removed before the owning page table. Note #2, writes - * to make mirror PTEs shadow-present are propagated to external page - * tables by __tdp_mmu_set_spte_atomic(), as KVM needs to ensure the - * external page table was successfully updated before marking the - * mirror SPTE present. + * When modifying leaf entries in mirrored page tables, propagate the + * changes to the external SPTE. Bug the VM on failure, as callers + * aren't prepared to handle errors, e.g. due to lock contention in the + * TDX-Module. Note, changes to non-leaf mirror SPTEs are handled by + * handle_removed_pt() (the TDX-Module requires that child entries are + * removed before the parent SPTE), and changes to non-present mirror + * SPTEs are handled by __tdp_mmu_set_spte_atomic() (KVM needs to set + * the external SPTE while the mirror SPTE is frozen so that installing + * a new SPTE is effectively an atomic operation). */ if (was_present && !was_leaf && (is_leaf || !is_present || WARN_ON_ONCE(pfn_changed))) handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared); else if (was_leaf && is_mirror_sptep(sptep) && !is_leaf) - kvm_x86_call(remove_external_spte)(kvm, gfn, level, old_spte); + KVM_BUG_ON(kvm_x86_call(set_external_spte)(kvm, gfn, old_spte, + new_spte, level), kvm); } static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm, diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 0f3d27699a3d..9f7789c5f0a7 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1751,11 +1751,11 @@ static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn, return 0; } -static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, - enum pg_level level, u64 mirror_spte) +static int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, + enum pg_level level, u64 old_spte) { struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); - kvm_pfn_t pfn = spte_to_pfn(mirror_spte); + kvm_pfn_t pfn = spte_to_pfn(old_spte); gpa_t gpa = gfn_to_gpa(gfn); u64 err, entry, level_state; @@ -1767,16 +1767,16 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, * there can't be anything populated in the private EPT. */ if (KVM_BUG_ON(!is_hkid_assigned(to_kvm_tdx(kvm)), kvm)) - return; + return -EIO; /* TODO: handle large pages. */ if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm)) - return; + return -EIO; err = tdh_do_no_vcpus(tdh_mem_range_block, kvm, &kvm_tdx->td, gpa, level, &entry, &level_state); if (TDX_BUG_ON_2(err, TDH_MEM_RANGE_BLOCK, entry, level_state, kvm)) - return; + return -EIO; /* * TDX requires TLB tracking before dropping private page. Do @@ -1792,14 +1792,15 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, err = tdh_do_no_vcpus(tdh_mem_page_remove, kvm, &kvm_tdx->td, gpa, level, &entry, &level_state); if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_REMOVE, entry, level_state, kvm)) - return; + return -EIO; err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, pfn, level); if (TDX_BUG_ON(err, TDH_PHYMEM_PAGE_WBINVD, kvm)) - return; + return -EIO; __tdx_quirk_reset_page(pfn, level); tdx_pamt_put(pfn, level); + return 0; } static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, u64 old_spte, @@ -1811,6 +1812,9 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, u64 old_spte, struct vcpu_tdx *tdx = to_tdx(vcpu); int ret; + if (is_shadow_present_pte(old_spte)) + return tdx_sept_remove_private_spte(kvm, gfn, level, old_spte); + if (KVM_BUG_ON(!vcpu, kvm)) return -EINVAL; @@ -3639,7 +3643,6 @@ void __init tdx_hardware_setup(void) vt_x86_ops.set_external_spte = tdx_sept_set_private_spte; vt_x86_ops.reclaim_external_sp = tdx_sept_reclaim_private_sp; - vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte; /* * FIXME: Wire up the PAMT hook iff DPAMT is supported, once VMXON is -- 2.53.0.rc1.217.geba53bf80e-goog