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 4112847606D; Fri, 7 Aug 2026 21:52:50 +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=1786139570; cv=none; b=EAbL0WqWpI6RUGnqPbphELzjEsl54OVVpFFlt59Hd9Vx+sOMzELmuas7T/zjXQk90PW0fEq01gfIKOTpeWD8p6BUHYxAdfZ1byPu8W+2X+KbYd8e2mW9/Oz2b00LPNvUHXeSZVKdikcsp4AGOiCR8q2gCiXHiRRsOy/15JVOdcY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786139570; c=relaxed/simple; bh=FoI3ZMvAwFhi7kaXsVeKkdELz832DofYJBPVRl9mtgo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=TRo9TxU9QPPUTLcWYQmspyxYvZ/UGkSB3h+j+18Eh59dVC5Jg8Vle5t/5+Cam5UIpp5vxhE2/IVD10BGy6H3xlOT95zXMvUOHJNn1anfIDPWz/oCxj9eFI0r1JpM+JtiOtpb3w8MIdS2lufqnKKVuN9c+zOWxfTmaqquimlC1ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MZ12nlj4; 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="MZ12nlj4" Received: by smtp.kernel.org (Postfix) with ESMTPS id DC1DAC2BCF7; Fri, 7 Aug 2026 21:52:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1786139569; bh=FoI3ZMvAwFhi7kaXsVeKkdELz832DofYJBPVRl9mtgo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=MZ12nlj4zg6jc33zJXDKBEAaD/2iRklHNAS3yqR77/cY7X3ZJKAcrJ58VSIp7lhGu ACCJy4wxgey6mcl1O1bfQezwlRgXCE9weYeGS1Bxn5M/OSPMvj/Je7PmCQNt7iGrDE S5hmlbXeV/ypmRrGSir13wZ+hn+H/TNo/ffnLg8fsX7v2CJDSOY9uwYskZzfRq/e4e JNyfbgPDjLv2fI83BbyS0+oKR6WkdWJ9A3yES7p7vG3wELaD/VDZMou/U8gsYdtxHC BK40gZGMnLuCMYH2q9rrdO0a6QC7TIsM+y2Qf6UxXhX98fpJ433AmOOKhmgaZBjtop qqA644ZGh4obA== 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 C7290C5ACD4; Fri, 7 Aug 2026 21:52:49 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Fri, 07 Aug 2026 14:53:00 -0700 Subject: [PATCH v10 21/41] KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260807-gmem-inplace-conversion-v10-21-2fc18ee6d3ba@google.com> References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> In-Reply-To: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@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 , John Hubbard , Peter Xu , tarunsahu@google.com, 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 , Xiaoyao Li X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1786139565; l=1641; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=5c5dIhQl3iWs3iceAiL8YJI/msPrnkAFg0lQ3bgVOW4=; b=UFZH2wM8ekLm4JtT1xYICDEeZuWmO10XkYOEwLNUAayGVaTkOQFrtplSWoHHOIzAaNHX6v238 KUC3rk4iwceAAxaAu6Ixrfp57qOfaUHTUgYifWYSAeKfD3DcUx7Bej/ 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 Reviewed-by: Fuad Tabba Reviewed-by: Xiaoyao Li Tested-by: Shivank Garg Signed-off-by: Ackerley Tng --- 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 39968610868fd..1ac60628b4c07 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10631,14 +10631,15 @@ 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 -- 2.55.0.654.g21b8a5bc05-goog