From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52A6427B4F7; Fri, 19 Jun 2026 00:31:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781829109; cv=none; b=L0/zlsaXgh+L3UoyhKc3Fk8SmlB4l4NLOegixL/Tm55PnlayLTxZIpQsF3apS0oh3o5U9GugUxdqV8JtaLxP0ICbR2g15Vm0t2FKtpZEldNGVB/8RQWxeRj5DJsvNjivMZIt8ESf1iZ55le2p2VAjgUXMFRhu9iGQwsRpy/EOWo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781829109; c=relaxed/simple; bh=fyOOtYfClGp09cjDKzYjVc3evf/urOJQVD3GzH69oRM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=eLAkouAKirtQ6oogfshfimNfQMkArzAaJ7GV9N5H9Uw0G7885hrj0/tw6hxzVmVCIvhSf2suDMypEAe6UQpRncrCwZ7hXWD7LRM2hwPtOLz7Zjs+5vnIZIZq9yitHuYH+d4fzzMSaWkmK1uW4Y923AwSzbmrtG7Hg0SEXALlPTg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TPlGqjqD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TPlGqjqD" Received: by smtp.kernel.org (Postfix) with ESMTPS id 36DB5C2BCC7; Fri, 19 Jun 2026 00:31:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1781829109; bh=fyOOtYfClGp09cjDKzYjVc3evf/urOJQVD3GzH69oRM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=TPlGqjqDI/PMYxZn5xjOYwF7kCayjYwZzXjWtCvfQBBsR+o5aBUNHa8P0RtkelR5T njG+iVbj5faKb06+4r5OgWAOaejxWytg8snWVAne03bxp+tLpRNRbCkYcBO6+JsB4b sx7FYlXH22R/CcVl5HD0FQgB+iOmSfzyAri9iokTLLktlf53uFwjduL5zrqwUFQGHZ DKf+tLgO0pNo/7Ef7mzlJu/YwiGdvp0ZdPac4shTpWs6ZrelZeV5MOqOcum8XHGTio tX4UAG/oOSaEcDt409fdpNxFbxRA8VISikCTBNlkcyQEta3GyXkaMr5wuWQTEe7vrv /1UoZpXReqNmQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D1FDCD98FE; Fri, 19 Jun 2026 00:31:49 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 18 Jun 2026 17:32:01 -0700 Subject: [PATCH v8 24/46] KVM: guest_memfd: Make in-place conversion the default Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260618-gmem-inplace-conversion-v8-24-9d2959357853@google.com> References: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> In-Reply-To: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , Vlastimil Babka , Baoquan He Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1781829104; l=3290; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=PRIZz/MUEDcYpJgxuI5DJhHZ5hfaG9jP2sr46JVINBY=; b=RxWU2Nn3vTjbe31iLWemaFC4u3fW67LS6mTsCASZGW43syFeZcJruijQ/SaPumweB4lztWXkR KKo4Y/vgPRQCh4wCRuGDPhwjndAdVzR8opSq/5IR4MMrz5c5YObQXT4 X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com From: Ackerley Tng Make in-place conversion the default if the arch has private mem. The default can be overridden at compile type by enabling CONFIG_KVM_VM_MEMORY_ATTRIBUTES, or at KVM load time through a module parameter. In-place conversion also implies tracking a guest's private/shared state in guest_memfd. To avoid inconsistencies in the way memory attributes are tracked between the per-VM or by guest_memfd, make the module_param read-only (0444). Document that using per-VM attributes for tracking private/shared state of guest memory is deprecated in favor of tracking in guest_memfd. Warn if the admin sets gmem_in_place_conversion as false when CONFIG_KVM_VM_MEMORY_ATTRIBUTES is not enabled. Add warning in the code path where guest memory is populated for a CoCo VM, since that's the earliest point in a CoCo VM's lifecycle where memory attributes are queried. Unlike other query sites, this site is exclusively used by CoCo VMs. Signed-off-by: Sean Christopherson --- arch/x86/kvm/Kconfig | 7 ++++++- virt/kvm/guest_memfd.c | 5 +++++ virt/kvm/kvm_main.c | 3 ++- 3 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index c28393dc664eb..a3c189d765150 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -85,7 +85,12 @@ config KVM_VM_MEMORY_ATTRIBUTES bool "Enable per-VM PRIVATE vs. SHARED attributes (for CoCo VMs)" help Enable support for tracking PRIVATE vs. SHARED memory using per-VM - memory attributes. + memory attributes. Using per-VM attributes are deprecated in favor + of tracking PRIVATE state in guest_memfd. Select this if you need + to run CoCo VMs using a VMM that doesn't support guest_memfd memory + attributes. + + If unsure, say N. config KVM_SW_PROTECTED_VM bool "Enable support for KVM software-protected VMs" diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 86c9f5b0863cb..5cb73543c03c8 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -1193,10 +1193,15 @@ static bool kvm_gmem_range_is_private(struct file *file, pgoff_t index, { struct maple_tree *mt = &GMEM_I(file_inode(file))->attributes; +#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES if (!gmem_in_place_conversion) return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE, KVM_MEMORY_ATTRIBUTE_PRIVATE); +#else + if (WARN_ON_ONCE(!gmem_in_place_conversion)) + return false; +#endif return kvm_gmem_range_has_attributes(mt, index, nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dd1d18a1d2f68..46e92b5dc3804 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -102,7 +102,8 @@ static bool __ro_after_init allow_unsafe_mappings; module_param(allow_unsafe_mappings, bool, 0444); #ifdef kvm_arch_has_private_mem -bool __ro_after_init gmem_in_place_conversion = false; +bool __ro_after_init gmem_in_place_conversion = !IS_ENABLED(CONFIG_KVM_VM_MEMORY_ATTRIBUTES); +module_param(gmem_in_place_conversion, bool, 0444); EXPORT_SYMBOL_FOR_KVM_INTERNAL(gmem_in_place_conversion); #endif -- 2.55.0.rc0.738.g0c8ab3ebcc-goog