From nobody Sun Feb 8 23:35:16 2026 Received: from mail-qk1-f202.google.com (mail-qk1-f202.google.com [209.85.222.202]) (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 5A0451F5435 for ; Wed, 4 Dec 2024 19:14:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733339664; cv=none; b=His0LI0yEq1x5L4ov/gzCfYd+j38fQ2eFjU0w2WUsL7vLMEroBPJdTqcwNFyhcilPM5okNFP4z8a3K9yIqFtXJxcZW59g8x3nC0aM7sgCuZT4bpIlX4MERChGlRGnRZuqz/m0DmdastBOL4bnvXdnCkzfSCTzREWvzmvPwnhQJ8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733339664; c=relaxed/simple; bh=7uKPJu5MZttnLGZHU4AcApt1HeYqG3NuIftXyYnBeQo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mNMFJ99NDnboCh/yADfP1YcqoPPMPCiDRtv7+lkKl/upGP6dzcs7Xdw5u2GnC8stm3V12UmznVvWk5ySYOgcTzgKOqzqMtQ2jTOsG3MunmK2eKPK7qL9ZmTiWZCfiNfZkwTUCtZg68OulXTM6jJbiOLyBIt+8zDI0IupwF3zrE8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jthoughton.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=JPNoCfaY; arc=none smtp.client-ip=209.85.222.202 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--jthoughton.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JPNoCfaY" Received: by mail-qk1-f202.google.com with SMTP id af79cd13be357-7b69c165621so16230885a.0 for ; Wed, 04 Dec 2024 11:14:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1733339661; x=1733944461; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=3LkXqlJAd4fQvrkyb/GIMYTRcu+OGHQVMPLjSgCJbVo=; b=JPNoCfaY5nuJ94PckOEx0Hov6Dil/1/XKbDK88WvHtYQ+sXLAShjjzstxZ8gtplxf8 0WB/9hlsxv9yIrXYE/5PSiyy8mrGpIlWMsaoN1Y2xaojf3FQTYjSBWH5hhK5t6hMm3Ri yafWI5m+DVPPc9lLjVLrFkR4fcHKcWtjRndprEwkipUwvmJVUAdyHGi/k3d5sR35gKsc OiFCqGjYvYsdPAg6Xpj8jdJG8p2ZOSgoy4qG4gEWxRu55IlBoANsI3BnhprViMF6IGqH TDNuRJlfKqgNAKPOcDfC6kifvYOOpLpUz1E5tUyDPOe4OHjoJLXPszDFwhMVPwoowdRQ aP3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733339661; x=1733944461; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3LkXqlJAd4fQvrkyb/GIMYTRcu+OGHQVMPLjSgCJbVo=; b=ZYZPJKAuZYvM7V4f1eAF0J/GRxf8z4hbZ5N9mC9Y36dX2eAXS3lKglLvg103lPTmrD +c4jMZCxLwmhK/s1niEJBLOK++Dz54HELXxG4Avs2INgVZSOjNrZqLEq3EYJWLYifrum T09F6OD8S2BXPpk4iS/NeeDaPH1FJV302ebShJWmg/VozyjJ8GrCn5t4rBLQj62d2T95 l6NowbDIErAaQJ/bG9k5U+rdrsb5Fz47AmWLHaTLA9QoGlwDuDwl5vE6uR9H5XcHSWK7 cec2FiJeRlgaZ2fQpCzTxQQAYUlOhHINjdDL/P/2e/RILWMI9D0T9AUvsHXcWuJE1fYE x5xQ== X-Forwarded-Encrypted: i=1; AJvYcCWdfAMRM1pZJwZMZxSu5J4tNk1Y2L7uqEAwNJGT5AFkpVw2ur75+EiD1km/Ed8tcHN9sGbCb66K+6Z8/vU=@vger.kernel.org X-Gm-Message-State: AOJu0YwVBw7AMxwdVky/E0z6izprcmvbGz/phJENZTy8dnmyTlxostQN 7HOxXxlhWghWCzQRE2mkOIFM+gyNXOnaeXRHSom5YBO19IEHqIUmwJx/MXTD5ffA6qzcEBP9U6s +P6Fr38E74zl20iKmfA== X-Google-Smtp-Source: AGHT+IG2YC7xA0GwWXk+cMxHq3A6sTNXchADXjRqs7ScJbz/ng/FU66WmJEiNslyAxyIF4C+tDiCnDtGEeEHeuoK X-Received: from uah9.prod.google.com ([2002:a05:6130:5209:b0:856:f0b0:717]) (user=jthoughton job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:40c2:b0:7b6:6b07:e80d with SMTP id af79cd13be357-7b6abbb7350mr835946485a.57.1733339661300; Wed, 04 Dec 2024 11:14:21 -0800 (PST) Date: Wed, 4 Dec 2024 19:13:41 +0000 In-Reply-To: <20241204191349.1730936-1-jthoughton@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241204191349.1730936-1-jthoughton@google.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241204191349.1730936-7-jthoughton@google.com> Subject: [PATCH v1 06/13] KVM: arm64: Add support for KVM_MEM_USERFAULT From: James Houghton To: Paolo Bonzini , Sean Christopherson Cc: Jonathan Corbet , Marc Zyngier , Oliver Upton , Yan Zhao , James Houghton , Nikita Kalyazin , Anish Moorthy , Peter Gonda , Peter Xu , David Matlack , Wang@google.com, Wei W , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Adhering to the requirements of KVM Userfault: 1. When it is toggled (either on or off), zap the second stage with kvm_arch_flush_shadow_memslot(). This is to (1) respect userfault-ness and (2) to reconstruct block mappings. 2. While KVM_MEM_USERFAULT is enabled, restrict new second-stage mappings to be PAGE_SIZE, just like when dirty logging is enabled. Signed-off-by: James Houghton --- I'm not 100% sure if kvm_arch_flush_shadow_memslot() is correct in this case (like if the host does not have S2FWB). --- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/mmu.c | 23 ++++++++++++++++++++++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index ead632ad01b4..d89b4088b580 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -38,6 +38,7 @@ menuconfig KVM select HAVE_KVM_VCPU_RUN_PID_CHANGE select SCHED_INFO select GUEST_PERF_EVENTS if PERF_EVENTS + select HAVE_KVM_USERFAULT help Support hosting virtualized guest machines. =20 diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index a71fe6f6bd90..53cee0bacb75 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1482,7 +1482,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys= _addr_t fault_ipa, * logging_active is guaranteed to never be true for VM_PFNMAP * memslots. */ - if (logging_active) { + if (logging_active || kvm_memslot_userfault(memslot)) { force_pte =3D true; vma_shift =3D PAGE_SHIFT; } else { @@ -1571,6 +1571,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phy= s_addr_t fault_ipa, mmu_seq =3D vcpu->kvm->mmu_invalidate_seq; mmap_read_unlock(current->mm); =20 + if (kvm_gfn_userfault(kvm, memslot, gfn)) { + kvm_prepare_memory_fault_exit(vcpu, gfn << PAGE_SHIFT, + PAGE_SIZE, write_fault, + exec_fault, false, true); + return -EFAULT; + } + pfn =3D __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0, &writable, &page); if (pfn =3D=3D KVM_PFN_ERR_HWPOISON) { @@ -2062,6 +2069,20 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, enum kvm_mr_change change) { bool log_dirty_pages =3D new && new->flags & KVM_MEM_LOG_DIRTY_PAGES; + u32 changed_flags =3D (new ? new->flags : 0) ^ (old ? old->flags : 0); + + /* + * If KVM_MEM_USERFAULT changed, drop all the stage-2 mappings so that + * we can (1) respect userfault-ness or (2) create block mappings. + */ + if ((changed_flags & KVM_MEM_USERFAULT) && change =3D=3D KVM_MR_FLAGS_ONL= Y) + kvm_arch_flush_shadow_memslot(kvm, old); + + /* + * Nothing left to do if not toggling dirty logging. + */ + if (!(changed_flags & KVM_MEM_LOG_DIRTY_PAGES)) + return; =20 /* * At this point memslot has been committed and there is an --=20 2.47.0.338.g60cca15819-goog