Add and use a new API for mapping a private pfn from guest_memfd into the TDP MMU from TDX's post-populate hook instead of partially open-coding the functionality into the TDX code. Sharing code with the pre-fault path sounded good on paper, but it's fatally flawed as simulating a fault loses the pfn, and calling back into gmem to re-retrieve the pfn creates locking problems, e.g. kvm_gmem_populate() already holds the gmem invalidation lock. Providing a dedicated API will also removing several MMU exports that ideally would not be exposed outside of the MMU, let alone to vendor code. On that topic, opportunistically drop the kvm_mmu_load() export. Leave kvm_tdp_mmu_gpa_is_mapped() alone for now; the entire commit that added kvm_tdp_mmu_gpa_is_mapped() will be removed in the near future. Cc: Michael Roth Cc: Yan Zhao Cc: Ira Weiny Cc: Vishal Annapurve Cc: Rick Edgecombe Link: https://lore.kernel.org/all/20250709232103.zwmufocd3l7sqk7y@amd.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu.h | 1 + arch/x86/kvm/mmu/mmu.c | 60 +++++++++++++++++++++++++++++++++++++++++- arch/x86/kvm/vmx/tdx.c | 10 +++---- 3 files changed, 63 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index b4b6860ab971..697b90a97f43 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -259,6 +259,7 @@ extern bool tdp_mmu_enabled; bool kvm_tdp_mmu_gpa_is_mapped(struct kvm_vcpu *vcpu, u64 gpa); int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code, u8 *level); +int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn); static inline bool kvm_memslots_have_rmaps(struct kvm *kvm) { diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 92ff15969a36..65300e43d6a1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4994,6 +4994,65 @@ long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, return min(range->size, end - range->gpa); } +int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) +{ + struct kvm_page_fault fault = { + .addr = gfn_to_gpa(gfn), + .error_code = PFERR_GUEST_FINAL_MASK | PFERR_PRIVATE_ACCESS, + .prefetch = true, + .is_tdp = true, + .nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(vcpu->kvm), + + .max_level = PG_LEVEL_4K, + .req_level = PG_LEVEL_4K, + .goal_level = PG_LEVEL_4K, + .is_private = true, + + .gfn = gfn, + .slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn), + .pfn = pfn, + .map_writable = true, + }; + struct kvm *kvm = vcpu->kvm; + int r; + + lockdep_assert_held(&kvm->slots_lock); + + if (KVM_BUG_ON(!tdp_mmu_enabled, kvm)) + return -EIO; + + if (kvm_gfn_is_write_tracked(kvm, fault.slot, fault.gfn)) + return -EPERM; + + r = kvm_mmu_reload(vcpu); + if (r) + return r; + + r = mmu_topup_memory_caches(vcpu, false); + if (r) + return r; + + do { + if (signal_pending(current)) + return -EINTR; + + if (kvm_test_request(KVM_REQ_VM_DEAD, vcpu)) + return -EIO; + + cond_resched(); + + guard(read_lock)(&kvm->mmu_lock); + + r = kvm_tdp_mmu_map(vcpu, &fault); + } while (r == RET_PF_RETRY); + + if (r != RET_PF_FIXED) + return -EIO; + + return 0; +} +EXPORT_SYMBOL_GPL(kvm_tdp_mmu_map_private_pfn); + static void nonpaging_init_context(struct kvm_mmu *context) { context->page_fault = nonpaging_page_fault; @@ -5977,7 +6036,6 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu) out: return r; } -EXPORT_SYMBOL_GPL(kvm_mmu_load); void kvm_mmu_unload(struct kvm_vcpu *vcpu) { diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 71da245d160f..c83e1ff02827 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -3151,15 +3151,12 @@ struct tdx_gmem_post_populate_arg { static int tdx_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, void __user *src, int order, void *_arg) { - u64 error_code = PFERR_GUEST_FINAL_MASK | PFERR_PRIVATE_ACCESS; - struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); struct tdx_gmem_post_populate_arg *arg = _arg; - struct kvm_vcpu *vcpu = arg->vcpu; + struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); + u64 err, entry, level_state; gpa_t gpa = gfn_to_gpa(gfn); - u8 level = PG_LEVEL_4K; struct page *src_page; int ret, i; - u64 err, entry, level_state; /* * Get the source page if it has been faulted in. Return failure if the @@ -3171,7 +3168,7 @@ static int tdx_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, if (ret != 1) return -ENOMEM; - ret = kvm_tdp_map_page(vcpu, gpa, error_code, &level); + ret = kvm_tdp_mmu_map_private_pfn(arg->vcpu, gfn, pfn); if (ret < 0) goto out; @@ -3234,7 +3231,6 @@ static int tdx_vcpu_init_mem_region(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *c !vt_is_tdx_private_gpa(kvm, region.gpa + (region.nr_pages << PAGE_SHIFT) - 1)) return -EINVAL; - kvm_mmu_reload(vcpu); ret = 0; while (region.nr_pages) { if (signal_pending(current)) { -- 2.51.0.318.gd7df087d1a-goog