From nobody Sun Feb 8 11:44:37 2026 Received: from mail-vs1-f73.google.com (mail-vs1-f73.google.com [209.85.217.73]) (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 E9EF72054E0 for ; Thu, 9 Jan 2025 20:49:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.217.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736455800; cv=none; b=XNEDxfX8lhnrXZjKTsjBfCbYzSSUwORFcKL4eaAmGHfGSf5Ux6I+pFKnrXSGpyZfVfqHperTYzVcKBEFnQpPBGRF53ZSRxdfipvFCgGpSQV4akoHfAb3dshj5QFG4PiVswwVYxFR3fk0Daju86EXfWT9cvViPtE5GmMPdt323Mc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736455800; c=relaxed/simple; bh=HNfpPbc0B5+oiokqFlBEDy9D4Azs1/AaYZmxA0SH3Sc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Ws3ZRyLqMHz1zWEpeanrsVUTq/OXN9QYbazuAxrHBrOpxa7G0Qmu/hHpkAzU/ZOKCBj2vyyDdibph5PqazWtBP1Ey0tYaWJHH+6VgPa+DE01wyZFPnvMk2QXrEZofsBNn/AEwtGeQN8iQjjhdefkOumD1v3VvuY9ElUAZztw11s= 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=LiAyCuwj; arc=none smtp.client-ip=209.85.217.73 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="LiAyCuwj" Received: by mail-vs1-f73.google.com with SMTP id ada2fe7eead31-4afd70f8125so150544137.1 for ; Thu, 09 Jan 2025 12:49:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1736455798; x=1737060598; 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=sy46ZKdMOYPNfFozinwrK5U4YnAl6mgCHSprJv2I5EE=; b=LiAyCuwjezVniwNKKASD5bBlkD7sA4eWP3Jg1YTyIlzNR1+HrBnfpLHFRCHADZcE7V xDsN8VNRWnN5JHAOMDPNV+pUHviJR6bl5DhyXnHmD4GKHpZsJE1L0BE3odnB3jtYFjhi +cFTsSmnmiDWuXFuy2UlDHnXY3m+2mmSIZbOfXrD9qAv8Ila4AipFifEtafpnror4Q3y rF21EUWJihAFlG8ISK00ovsfuaMc+xHzVEpPYktVcpNmXbIsgqemMxdaw4Nz7ZN9HTYS bsFxMIxeXRZQqh3+X7tHmx97R6cGyr4ae1WtnAB2Q5VrWbN/LhjS3jcAPwu3pQ9za3cS hnIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736455798; x=1737060598; 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=sy46ZKdMOYPNfFozinwrK5U4YnAl6mgCHSprJv2I5EE=; b=B2Zfe0FNscgOFto32Ueo8DEzqsd3+h7PolMdk260IFM4zWt+0AtlvVSthkONOG80Y+ N+3h3PILOPVeIoBRxokGyOhm9yw8UsJDngrO6EuhjmVqlI3Tnr5P2XoMOnjmwEJl67SH /cqx1XIRMqrC5YMmOUclo5tf8RMMbzBvs+weeMvAzpH57BodR8kVa2lJuL540mfzzy9W 966FUaSTgYhO6GWk7tlrr2XEQCpSue4JYqJJ6XVcNXGbt+DDGj7rjX+PBVTyIHdXQa+O Uv3gy0FH2b7mRs3XWU0qo18HrxPZrta9pd/kkZccJQaB6f6csFF/th6/JVTs2wb//1HQ rdeQ== X-Forwarded-Encrypted: i=1; AJvYcCXJd6JB0wfQ9HuU/wYeK04i/jLR4AzRb9GVaSjRShTXYhm0lmpKgmNQYpf/tNdx6wiEDYDQ9wbNtrFvDls=@vger.kernel.org X-Gm-Message-State: AOJu0YymSM7/v6o0jMa38if6DNOSULlkAyisMdQRYBh+GHpvDFV8hQZX xHSR2xqnapufqW8Q5irbumDY9fCnTHe3Wh9aqvL/RcXRxJW4HzZXrB8jsNtzHUrfTPcdpMlyauv a/W7MKkQWo5bhzo0tFA== X-Google-Smtp-Source: AGHT+IGxjoRseI0ptp1PpNGkamYSZpMVzGlMOrPqkiBhNVZ0uPSquo0Jh6/07xFgWyNiCB/pmTP7I9swsH2tkGpZ X-Received: from vsvj16.prod.google.com ([2002:a05:6102:3e10:b0:4b4:f067:c6f]) (user=jthoughton job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6102:c12:b0:4b1:1a11:fe3 with SMTP id ada2fe7eead31-4b3d0f15e35mr7763898137.8.1736455797824; Thu, 09 Jan 2025 12:49:57 -0800 (PST) Date: Thu, 9 Jan 2025 20:49:19 +0000 In-Reply-To: <20250109204929.1106563-1-jthoughton@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250109204929.1106563-1-jthoughton@google.com> X-Mailer: git-send-email 2.47.1.613.gc27f4b7a9f-goog Message-ID: <20250109204929.1106563-4-jthoughton@google.com> Subject: [PATCH v2 03/13] KVM: Allow late setting of KVM_MEM_USERFAULT on guest_memfd memslot 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 , wei.w.wang@intel.com, 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" Currently guest_memfd memslots can only be deleted. Slightly change the logic to allow KVM_MR_FLAGS_ONLY changes when the only flag being changed is KVM_MEM_USERFAULT. Signed-off-by: James Houghton --- virt/kvm/kvm_main.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 4bceae6a6401..882c1f7b4aa8 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2015,9 +2015,6 @@ int __kvm_set_memory_region(struct kvm *kvm, if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages) return -EINVAL; } else { /* Modify an existing slot. */ - /* Private memslots are immutable, they can only be deleted. */ - if (mem->flags & KVM_MEM_GUEST_MEMFD) - return -EINVAL; if ((mem->userspace_addr !=3D old->userspace_addr) || (npages !=3D old->npages) || ((mem->flags ^ old->flags) & KVM_MEM_READONLY)) @@ -2031,6 +2028,16 @@ int __kvm_set_memory_region(struct kvm *kvm, return 0; } =20 + /* + * Except for being able to set KVM_MEM_USERFAULT, private memslots are + * immutable, they can only be deleted. + */ + if (mem->flags & KVM_MEM_GUEST_MEMFD && + !(change =3D=3D KVM_MR_CREATE || + (change =3D=3D KVM_MR_FLAGS_ONLY && + (mem->flags ^ old->flags) =3D=3D KVM_MEM_USERFAULT))) + return -EINVAL; + if ((change =3D=3D KVM_MR_CREATE || change =3D=3D KVM_MR_MOVE) && kvm_check_memslot_overlap(slots, id, base_gfn, base_gfn + npages)) return -EEXIST; @@ -2046,7 +2053,7 @@ int __kvm_set_memory_region(struct kvm *kvm, new->npages =3D npages; new->flags =3D mem->flags; new->userspace_addr =3D mem->userspace_addr; - if (mem->flags & KVM_MEM_GUEST_MEMFD) { + if (mem->flags & KVM_MEM_GUEST_MEMFD && change =3D=3D KVM_MR_CREATE) { r =3D kvm_gmem_bind(kvm, new, mem->guest_memfd, mem->guest_memfd_offset); if (r) goto out; --=20 2.47.1.613.gc27f4b7a9f-goog