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 7466A3A3E75; Tue, 28 Apr 2026 23:25:19 +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=1777418719; cv=none; b=TzNZHIVG5O63AW6yuDfOXJx9CIRODvbvbaIauwUbfqD17ekOlULYs9ELcYDUUgUasUdR+X8bHfNG35rbt/1QXMj/ACmhs7VKSCjrXlimc8qkhINaQdNOstq0foPJsVbmgOqzmBkKk5gVfN0klbLsyMfnkRpfM5TyhmySyjLUsWo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777418719; c=relaxed/simple; bh=zncE2hxQkprEk/co3eBc2SR0h1oYBU1WvKX4YOZi9bM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=YsDr90TROPqrjHQXZCxNDYWfj38QFuQ0Nk6Aj5R9F0cqMGCImV6ZGxLRP1KnIb83kB7iRqXeJtB8iSC/zSnLyoJHdE8ZMrJKv1v6N2nrPJ+csMVc3pfINH1t71BBMXqVeC592xXswc5fo9fDDjbvVBDOCDIdLBMCNfGkWIpt8aE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KUZBH2j5; 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="KUZBH2j5" Received: by smtp.kernel.org (Postfix) with ESMTPS id 407DDC2BCB8; Tue, 28 Apr 2026 23:25:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777418719; bh=zncE2hxQkprEk/co3eBc2SR0h1oYBU1WvKX4YOZi9bM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=KUZBH2j5InYqZEArSttoYJSjeqs4A/ExMhyoDcp25A8Wz8G9/mSZcuLXBAodSZ1gl H+1NyM1FpGLECjTF4lXRXex+qmXR7w2YczKNVE7aC5uAH6PfnOC1t8bNkI+CXxpOCb IbsFwKAvIyJ3lkupbeSAizS6VBtk6uCiMgR8oc07MRuR1NoJvL/jfidW7dzpFLZk7b AXsPioKlZqSzlS/QuVwy0nCbbROpVmRVh46/8byaGXZVxoJC5WUclq58cLgnkwEYD9 WcBTlO8VhgdYVxMSG7JJ5ALHLXHVPHnk6PjD95vSto/EySxo9zvPWfdXqUOo8IG219 SMnIfeS3T+BOw== 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 37697FF8877; Tue, 28 Apr 2026 23:25:19 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Tue, 28 Apr 2026 16:25:19 -0700 Subject: [PATCH RFC v5 24/53] KVM: SEV: Make 'uaddr' parameter optional for KVM_SEV_SNP_LAUNCH_UPDATE Precedence: bulk X-Mailing-List: linux-trace-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: <20260428-gmem-inplace-conversion-v5-24-d8608ccfca22@google.com> References: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@google.com> In-Reply-To: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@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, ira.weiny@intel.com, 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, 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 , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Jason Gunthorpe , Vlastimil Babka 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=1777418714; l=6631; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=6I5qY356QuKhvOxH1JQe8xcoUJLrBsuBlWTdyFO/bYI=; b=3BKZsofxSpmgNd3PfWxQbf4StcoBe8YmYcPFtSyrf7dW6HwahUfNHnny0P0z2E9XtxJTwkPtk oW/xZZKZ1dNAcwDaMXpkp9YNj3ce2/puK45bRgGtx1pY7P5UFEHe9vZ 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: Michael Roth For vm_memory_attributes=1, in-place conversion/population is not supported, so the initial contents necessarily must need to come from a separate src address, which is enforced by the current implementation. However, for vm_memory_attributes=0, it is possible for guest memory to be initialized directly from userspace by mmap()'ing the guest_memfd and writing to it while the corresponding GPA ranges are in a 'shared' state before converting them to the 'private' state expected by KVM_SEV_SNP_LAUNCH_UPDATE. Update the handling/documentation for KVM_SEV_SNP_LAUNCH_UPDATE to allow for 'uaddr' to be set to NULL when vm_memory_attributes=0, which SNP_LAUNCH_UPDATE will then use to determine when it should/shouldn't copy in data from a separate memory location. Continue to enforce non-NULL for the original vm_memory_attributes=1 case. Signed-off-by: Michael Roth [Added src_page check in error handling path when the firmware command fails] [Dropped ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES] Signed-off-by: Ackerley Tng --- Documentation/virt/kvm/x86/amd-memory-encryption.rst | 19 +++++++++++++++---- arch/x86/kvm/svm/sev.c | 18 +++++++++++++----- virt/kvm/kvm_main.c | 1 + 3 files changed, 29 insertions(+), 9 deletions(-) diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst index b2395dd4769de..3b9f36a55a95b 100644 --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst @@ -503,7 +503,12 @@ secrets. It is required that the GPA ranges initialized by this command have had the KVM_MEMORY_ATTRIBUTE_PRIVATE attribute set in advance. See the documentation -for KVM_SET_MEMORY_ATTRIBUTES for more details on this aspect. +for KVM_SET_MEMORY_ATTRIBUTES/KVM_SET_MEMORY_ATTRIBUTES2 for more details on +this aspect. If running with kvm.vm_memory_attributes=0 (to allow for +guest_memfd to handle memory attributes and allow for in-place conversion of +pages between shared/private), the 'PRESERVED' flag/content mode (which is +only available via the KVM_SET_MEMORY_ATTRIBUTES2 interface) must be used +when setting the range to private prior to issuing this ioctl. Upon success, this command is not guaranteed to have processed the entire range requested. Instead, the ``gfn_start``, ``uaddr``, and ``len`` fields of @@ -511,9 +516,15 @@ range requested. Instead, the ``gfn_start``, ``uaddr``, and ``len`` fields of remaining range that has yet to be processed. The caller should continue calling this command until those fields indicate the entire range has been processed, e.g. ``len`` is 0, ``gfn_start`` is equal to the last GFN in the -range plus 1, and ``uaddr`` is the last byte of the userspace-provided source -buffer address plus 1. In the case where ``type`` is KVM_SEV_SNP_PAGE_TYPE_ZERO, -``uaddr`` will be ignored completely. +range plus 1, and ``uaddr`` (if specified) is the last byte of the +userspace-provided source buffer address plus 1. + +In the case where ``type`` is KVM_SEV_SNP_PAGE_TYPE_ZERO, ``uaddr`` will be +ignored completely. Otherwise, ``uaddr`` is required if +kvm.vm_memory_attributes=0 and optional if kvm.vm_memory_attributes=1, since +in the latter case guest memory can be initialized directly from userspace +prior to converting it to private and passing the GPA range on to this +interface. Parameters (in): struct kvm_sev_snp_launch_update diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index c2126b3c30724..bf10d24907a00 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2343,7 +2343,15 @@ static int sev_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int level; int ret; - if (WARN_ON_ONCE(sev_populate_args->type != KVM_SEV_SNP_PAGE_TYPE_ZERO && !src_page)) + /* + * For vm_memory_attributes=1, in-place conversion/population is not + * supported, so the initial contents necessarily need to come from a + * separate src address. For vm_memory_attributes=0, this isn't + * necessarily the case, since the pages may have been populated + * directly from userspace before calling KVM_SEV_SNP_LAUNCH_UPDATE. + */ + if (vm_memory_attributes && + sev_populate_args->type != KVM_SEV_SNP_PAGE_TYPE_ZERO && !src_page) return -EINVAL; ret = snp_lookup_rmpentry((u64)pfn, &assigned, &level); @@ -2390,7 +2398,7 @@ static int sev_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, */ if (ret && !snp_page_reclaim(kvm, pfn) && sev_populate_args->type == KVM_SEV_SNP_PAGE_TYPE_CPUID && - sev_populate_args->fw_error == SEV_RET_INVALID_PARAM) { + sev_populate_args->fw_error == SEV_RET_INVALID_PARAM && src_page) { void *src_vaddr = kmap_local_page(src_page); void *dst_vaddr = kmap_local_pfn(pfn); @@ -2422,8 +2430,8 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) if (copy_from_user(¶ms, u64_to_user_ptr(argp->data), sizeof(params))) return -EFAULT; - pr_debug("%s: GFN start 0x%llx length 0x%llx type %d flags %d\n", __func__, - params.gfn_start, params.len, params.type, params.flags); + pr_debug("%s: GFN start 0x%llx length 0x%llx type %d flags %d src %llx\n", __func__, + params.gfn_start, params.len, params.type, params.flags, params.uaddr); if (!params.len || !PAGE_ALIGNED(params.len) || params.flags || (params.type != KVM_SEV_SNP_PAGE_TYPE_NORMAL && @@ -2479,7 +2487,7 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) params.gfn_start += count; params.len -= count * PAGE_SIZE; - if (params.type != KVM_SEV_SNP_PAGE_TYPE_ZERO) + if (src && params.type != KVM_SEV_SNP_PAGE_TYPE_ZERO) params.uaddr += count * PAGE_SIZE; if (copy_to_user(u64_to_user_ptr(argp->data), ¶ms, sizeof(params))) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index ba195bb239aaa..3bf212fd99193 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -105,6 +105,7 @@ module_param(allow_unsafe_mappings, bool, 0444); #ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES bool vm_memory_attributes = true; module_param(vm_memory_attributes, bool, 0444); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(vm_memory_attributes); #endif DEFINE_STATIC_CALL_RET0(__kvm_get_memory_attributes, kvm_get_memory_attributes_t); EXPORT_SYMBOL_FOR_KVM_INTERNAL(STATIC_CALL_KEY(__kvm_get_memory_attributes)); -- 2.54.0.545.g6539524ca2-goog