From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 C1AC718C15 for ; Mon, 30 Oct 2023 16:10:50 +0000 (UTC) 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="OVEeW0dF" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-da033914f7cso3990938276.0 for ; Mon, 30 Oct 2023 09:10:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698682249; x=1699287049; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=3/eJ4eIlm/QBKFGigGc88HjjNKR0Bxic1+CMFaJ9ygg=; b=OVEeW0dFYghTa15q2Mo6yQyJrpladLzfpF7iGt4dD177ZUvmbKWczin6NAlHEOV3xx SswW4JSJEg2Aw140kUjdtk8MVKaCZCQGKE2qf/PQYVYbviMJoQ23T9bkN4t6Zy1bzsJl xERQhB4M7wnZ871AUNZ+LjM4YImiP5flZFP9TVfX10BjhZdjATmlkUdu0je9gOv+HGcb EKyNcGhSp6HwTronY7ITMuORjX7cE+ASFbOdEq/2R5OVhFDiSD8o/Dm4S0Q2YnAjRBLV fZ3EegfL8SQ83gXpsAg3tbV22s+47lc7LaArrKpt2CPkeU1/ISCBVGudBcxHtfMenWKW d/Tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698682249; x=1699287049; 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=3/eJ4eIlm/QBKFGigGc88HjjNKR0Bxic1+CMFaJ9ygg=; b=mH2c5wOd/u5iOQmByE8BVcGcvSHtoSu57G6MSYUpKW8D1hFhXK+yNDaVGKKfiyBa5J QkS46e389MuOrRfsqnKpZdTOMurDEMAaBhL7XNcmQPryxHPLkMA/FOTrcO2+3+sCdS0k d1oEZe6+dA2/5jjcgDmdGvC7iOStkKcZ3MTjKlNqbq9O0IQxJ8mQT3gudFRP0U0sOEPW itAnJ3G8msfDtGORnhiplRyb7W+Mp9Mdaj8bc64AUyE8tkcitspoR8le7o7ez/IVS4vI uxar6tZ4xrzdwLoq2aBvwfeh0UKhSP6mmcV/GihQ7/kCMgCV6CdOP5u9yk+9ms5LVwWH gguA== X-Gm-Message-State: AOJu0YwkNXXHdAfB2EByfqVv8RcfrZHvTHV+0cxFKS/IAxn+p31AK465 OR1objg03vNS2wg7UWQwieRKBx3OPoc= X-Google-Smtp-Source: AGHT+IG/nj4LaX3JPzHZqsehR5FWhArOOi7E0ApKeqEkunCLK98IonUlxUU55c5VBDsNlZFSGb1icvfnahw= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:1083:b0:d9a:c3b8:4274 with SMTP id v3-20020a056902108300b00d9ac3b84274mr243782ybu.7.1698682249642; Mon, 30 Oct 2023 09:10:49 -0700 (PDT) Date: Mon, 30 Oct 2023 16:10:48 +0000 In-Reply-To: Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231027182217.3615211-1-seanjc@google.com> <20231027182217.3615211-14-seanjc@google.com> Message-ID: Subject: Re: [PATCH v13 13/35] KVM: Introduce per-page memory attributes From: Sean Christopherson To: Chao Gao Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , "=?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?=" , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" On Mon, Oct 30, 2023, Chao Gao wrote: > On Fri, Oct 27, 2023 at 11:21:55AM -0700, Sean Christopherson wrote: > >From: Chao Peng > > > >In confidential computing usages, whether a page is private or shared is > >necessary information for KVM to perform operations like page fault > >handling, page zapping etc. There are other potential use cases for > >per-page memory attributes, e.g. to make memory read-only (or no-exec, > >or exec-only, etc.) without having to modify memslots. > > > >Introduce two ioctls (advertised by KVM_CAP_MEMORY_ATTRIBUTES) to allow > >userspace to operate on the per-page memory attributes. > > - KVM_SET_MEMORY_ATTRIBUTES to set the per-page memory attributes to > > a guest memory range. > > > - KVM_GET_SUPPORTED_MEMORY_ATTRIBUTES to return the KVM supported > > memory attributes. > > This ioctl() is already removed. So, the changelog is out-of-date and needs > an update. Doh, I lost track of this and the fixup for KVM_CAP_MEMORY_ATTRIBUTES below. > >+:Capability: KVM_CAP_MEMORY_ATTRIBUTES > >+:Architectures: x86 > >+:Type: vm ioctl > >+:Parameters: struct kvm_memory_attributes(in) > > ^ add one space here? Ah, yeah, that does appear to be the standard. > > > >+static bool kvm_pre_set_memory_attributes(struct kvm *kvm, > >+ struct kvm_gfn_range *range) > >+{ > >+ /* > >+ * Unconditionally add the range to the invalidation set, regardless of > >+ * whether or not the arch callback actually needs to zap SPTEs. E.g. > >+ * if KVM supports RWX attributes in the future and the attributes are > >+ * going from R=>RW, zapping isn't strictly necessary. Unconditionally > >+ * adding the range allows KVM to require that MMU invalidations add at > >+ * least one range between begin() and end(), e.g. allows KVM to detect > >+ * bugs where the add() is missed. Rexlaing the rule *might* be safe, > > ^^^^^^^^ Relaxing > > >@@ -4640,6 +4850,17 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) > > case KVM_CAP_BINARY_STATS_FD: > > case KVM_CAP_SYSTEM_EVENT_DATA: > > return 1; > >+#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES > >+ case KVM_CAP_MEMORY_ATTRIBUTES: > >+ u64 attrs = kvm_supported_mem_attributes(kvm); > >+ > >+ r = -EFAULT; > >+ if (copy_to_user(argp, &attrs, sizeof(attrs))) > >+ goto out; > >+ r = 0; > >+ break; > > This cannot work, e.g., no @argp in this function and is fixed by a later commit: > > fcbef1e5e5d2 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory") I'll post a fixup patch for all of these, thanks much!