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 3E2DA3BED24; Thu, 10 Sep 2026 23:55:39 +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=1789084539; cv=none; b=u0q0DQuazj6wSzba5GFNzW46QMZLiolOwju6rBctnO/ZmASuA4bpqztGdCI8Y4iNqdivYo/Q+PGtX72M8eoBrlUYcarSo777j0RWFS407D7ehI6DDLdjvR+GlB9opeSR5YJEjZ8VgcfUWOj6MqvEkknxBpGf6+0XgNFMg51AnYk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789084539; c=relaxed/simple; bh=Yr1oBLTtdwaGJyWjVIRhbbXF2lJ13BwSgT203mgx3k4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=UhMt7/ZStxEKwTrblw/2yNCr7O/fppYO81SGDAG7BdKyHoncfvD+5PE3+Afg249wFS+jIRXh4B5/UixelbmqiIKYCf0RBOaj+Zp6ve1WH65rrBS9Kpo1I0mQVHVFwaCFVDIsB5rzIEjk37qQewF4RmPreU3dKBy1hdKzKvifQtA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dBKt8TQD; 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="dBKt8TQD" Received: by smtp.kernel.org (Postfix) with ESMTPS id 17B7FC2BD04; Thu, 10 Sep 2026 23:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789084539; bh=Yr1oBLTtdwaGJyWjVIRhbbXF2lJ13BwSgT203mgx3k4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=dBKt8TQD2PFaRSH2tTbwsIbxT/fdsxDWDKi5YzZMb8ka8kl7ZflJA0RnTN7riPytP urTBUKr+fwtRV+9piCUjuV5dJh4lJe5ubM0F9x5q86aAXZ6WV58WMEAuEbZN1Hz7LP m+ImjQMPiOnbazmfZxpvo3MGRMBYhI3mUnM/dJKhgOLn9q7zQrK5pbteMCteERaq4r 3pmu0581+29Yv8+XvhZb8rZKWpevCwUlmXdtXXXEz8n5DEU6QF7uhgsbfDI4GKvmZD KYJQq+1AhQxp6SvkDP+W/3UUzPJ7LAj9dRNQETToZ1SwBMPvRIqw/N+I7oDa0RRmp/ PZGmlWPtpd7ig== 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 F01DBC88E45; Thu, 10 Sep 2026 23:55:38 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 10 Sep 2026 16:55:49 -0700 Subject: [PATCH v13 23/44] KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs Precedence: bulk X-Mailing-List: kvm@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: <20260910-gmem-inplace-conversion-v13-23-dd6fbf94f4e1@google.com> References: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@google.com> In-Reply-To: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@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, 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 , John Hubbard , Peter Xu , tarunsahu@google.com, Randy Dunlap , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , Fuad Tabba , 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 , Xiaoyao Li X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1789084533; l=1694; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=RrmAu7ijt4T2BgV+VK4Wz6c8RsidOxZAmXDSW4OkVVw=; b=dSAQjeKmiLaKcZ3hz47vvakbuCRsgz9FVSQ5XqgaYCqPZV1uwCfGkSyysLvwAbEf1IHgLbigg mHLMql6CMxDAlFlXxnySZnQASx4VI9Do9ieGbBmxMLcQnNva9MvwGp/ 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: Sean Christopherson Now that guest_memfd supports tracking private vs. shared within gmem itself, allow userspace to specify INIT_SHARED on a guest_memfd instance for x86 Confidential Computing (CoCo) VMs, so long as in-place conversion is enabled, i.e. when it's actually possible for a guest_memfd instance to contain shared memory. Signed-off-by: Sean Christopherson Signed-off-by: Ackerley Tng Tested-by: Shivank Garg Reviewed-by: Fuad Tabba Reviewed-by: Xiaoyao Li Reviewed-by: Binbin Wu --- arch/x86/kvm/x86.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 75e03a2f79db2..c081e4b9b25de 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10637,14 +10637,15 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) } #ifdef CONFIG_KVM_GUEST_MEMFD -/* - * KVM doesn't yet support initializing guest_memfd memory as shared for VMs - * with private memory (the private vs. shared tracking needs to be moved into - * guest_memfd). - */ bool kvm_arch_supports_gmem_init_shared(struct kvm *kvm) { - return !kvm_arch_has_private_mem(kvm); + /* + * INIT_SHARED is supported if in-place conversion is enabled, or if + * the VM doesn't support private memory. If the VM has private memory + * and in-place conversion is disabled, then guest_memfd can _only_ be + * used for private memory. + */ + return gmem_in_place_conversion || !kvm_arch_has_private_mem(kvm); } #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT -- 2.55.0.1007.g17ff1f9808-goog