From nobody Fri Oct 3 15:31:39 2025 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B5ECF1DFF7 for ; Fri, 29 Aug 2025 00:06:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756425987; cv=none; b=bKD7y5PaD/tnqdbdeT+qiN2F0W+Lb+hWXYMEWD2uRUu/0f2icfgNm6OUiZjaXKz9sXqJM3EmFLbrAu9vWC/HnsLwFShj5hgTx01SP7tPY62KR4GfbN8GXiuhFp9RqVTAGeG1MvNYZxCtqkMpH2vOc11lOkjOJR1cDqqTx88ocvM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756425987; c=relaxed/simple; bh=KCT7Nt9F54BAobdhz2zR/stlMdrvovd8onIkINoAfd8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hbNV4zNmSiTlEsJMtN3QdXY01WhjLDQ+OlER0gjwDiwOnTwAnZ4cy6lAaDod4L3uvXjjmWf3fkdv43aX6YLTY0AMjnPMJwprm6a4wwz+En5YHE+zQ9KUs/fyt4WgM0QsfOS0Q7OyNhEGoQdc9CYcMKCayabyHWaqD6SQp7Lg/BI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=4FKfHUlh; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="4FKfHUlh" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-3251961140bso1467371a91.2 for ; Thu, 28 Aug 2025 17:06:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1756425985; x=1757030785; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=QsIXvnuSh6UUFD5YwAdWYJa2UJyM2Kr57W7DFFX+dvk=; b=4FKfHUlh22KoahnDmFNzByidSTXPl8NsRcAQxmNBO1mfxUXDwVqJBJmNMhK7tEHwWt 3+Y/u9KyV2IPkHOg3AuDmqqjkhDOOqmK1bQJlZIzgSCi5u1CBTXpUDP3CAYMUMRe2iuz uH8xX9asHGXlb1VcTChRHwu0Q89Zsxsyc9FJ3JOKcBxcnv1s3OJexkFPLbKqZj5dKFHo Nr/zSgjnL9RDEtPOyPvYt5PGR/i8ig6SJVUd2h3eZnmX9hRkXu8hk6YVIrhvY1ELfDEX sLJbkuVBc47KLstym/aTUkVJmU3AT8HhpAYPnFo9fdp6evgMF+zdvS32Vif5/22czUhD AOzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756425985; x=1757030785; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=QsIXvnuSh6UUFD5YwAdWYJa2UJyM2Kr57W7DFFX+dvk=; b=O1043N7Lx2JnBoztAbwPnqDXp40CQFnaaagMZibdlVWY6LaMOLArcMsr+EU0bmYHVO jANKiJtHaOlcgzkr8dD49QEOmrqLkFavTx3VhGjekzeeTOB3QAx2TGtVae8n3veHzOTH KwGkAbx/Jb5bHgIMwZDrEwfQ3Odfu4Xj+XFrTCNVm/b/5RkUdkqLalJhwpirj/3AXdud 5xDbNDEhP91ox1i/h9S84nwQisXx0K/0lKCPlsP6POGPK0+AkHUXLMcxTUD0T/aQAA0x M2MU5GJA4wQFHRp4Qqxh6e1YLQn9FhQ4fn6eoRbj2V6C1rPI0uzTn3al6PZh6uMdfUwo gqCg== X-Forwarded-Encrypted: i=1; AJvYcCWbZQWu0W3pzMonhxgg/nRFWc3ZDYVfIVtfBJP8z4+nSzcZe494dNd1lEuXsFcGK+cTD2FvXS9e2WD03E8=@vger.kernel.org X-Gm-Message-State: AOJu0YyGFtEqZNHq1i4E73Q4s0U5+LaL3KNGPYTf0PdEv129clNF9XWS KTfRV0/KdiUGqbWilyXhhlM73hov+IKTW7NxAAkAr7c/KHsd9xYIarF4Dprz3ModIUq7TinzNrG MMohP7w== X-Google-Smtp-Source: AGHT+IGQe12O8dbqInnyVob7Pm608CuTv+jQ1L1sCiFT2qw6Fyu996exnKxTQRc1JDH1tdMc9QZ8SiBK2nQ= X-Received: from pjbsc16.prod.google.com ([2002:a17:90b:5110:b0:327:d636:2d1e]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:e890:b0:246:e8cc:8cef with SMTP id d9443c01a7336-246e8cc919bmr202029185ad.3.1756425985105; Thu, 28 Aug 2025 17:06:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 28 Aug 2025 17:06:02 -0700 In-Reply-To: <20250829000618.351013-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250829000618.351013-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.318.gd7df087d1a-goog Message-ID: <20250829000618.351013-3-seanjc@google.com> Subject: [RFC PATCH v2 02/18] KVM: x86/mmu: Add dedicated API to map guest_memfd pfn into TDP MMU From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ira Weiny , Kai Huang , Michael Roth , Yan Zhao , Vishal Annapurve , Rick Edgecombe , Ackerley Tng Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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; =20 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); =20 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); } =20 +int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_= t pfn) +{ + struct kvm_page_fault fault =3D { + .addr =3D gfn_to_gpa(gfn), + .error_code =3D PFERR_GUEST_FINAL_MASK | PFERR_PRIVATE_ACCESS, + .prefetch =3D true, + .is_tdp =3D true, + .nx_huge_page_workaround_enabled =3D is_nx_huge_page_enabled(vcpu->kvm), + + .max_level =3D PG_LEVEL_4K, + .req_level =3D PG_LEVEL_4K, + .goal_level =3D PG_LEVEL_4K, + .is_private =3D true, + + .gfn =3D gfn, + .slot =3D kvm_vcpu_gfn_to_memslot(vcpu, gfn), + .pfn =3D pfn, + .map_writable =3D true, + }; + struct kvm *kvm =3D 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 =3D kvm_mmu_reload(vcpu); + if (r) + return r; + + r =3D 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 =3D kvm_tdp_mmu_map(vcpu, &fault); + } while (r =3D=3D RET_PF_RETRY); + + if (r !=3D 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 =3D nonpaging_page_fault; @@ -5977,7 +6036,6 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu) out: return r; } -EXPORT_SYMBOL_GPL(kvm_mmu_load); =20 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 pf= n, void __user *src, int order, void *_arg) { - u64 error_code =3D PFERR_GUEST_FINAL_MASK | PFERR_PRIVATE_ACCESS; - struct kvm_tdx *kvm_tdx =3D to_kvm_tdx(kvm); struct tdx_gmem_post_populate_arg *arg =3D _arg; - struct kvm_vcpu *vcpu =3D arg->vcpu; + struct kvm_tdx *kvm_tdx =3D to_kvm_tdx(kvm); + u64 err, entry, level_state; gpa_t gpa =3D gfn_to_gpa(gfn); - u8 level =3D PG_LEVEL_4K; struct page *src_page; int ret, i; - u64 err, entry, level_state; =20 /* * 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, gf= n_t gfn, kvm_pfn_t pfn, if (ret !=3D 1) return -ENOMEM; =20 - ret =3D kvm_tdp_map_page(vcpu, gpa, error_code, &level); + ret =3D kvm_tdp_mmu_map_private_pfn(arg->vcpu, gfn, pfn); if (ret < 0) goto out; =20 @@ -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_SHI= FT) - 1)) return -EINVAL; =20 - kvm_mmu_reload(vcpu); ret =3D 0; while (region.nr_pages) { if (signal_pending(current)) { --=20 2.51.0.318.gd7df087d1a-goog