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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=1788135915; l=3571; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=njc9wPSBjD6tmKwt2PhlMiU1O1S+4eQ2KtODaEWL4xY=; b=xet/UHJxW/icBX2JrNtGGU28LtYGzpL8u5/A2zHQu7TLEnsVz5ggJjGJpERO2fdfgD7Fxr51C ip40S/BlqIICNfbuaM0UoGpRZF7btZdQpGjyeJFTBr9EgNvYJ9H3K1t 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 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 4786A20002 X-Stat-Signature: ii5rjok9ydkff7oq3r1gu1xj3c1batwo X-HE-Tag: 1788135931-793815 X-HE-Meta: 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 nIYjDKvE o2iBO9Ds1oxY8ZjoQehZ9WANaB7grJTVvU3EWOWZfwwZJX0AMarIHH/WqLJmUwhGHmmdOZR416iQRBWRI/K0mXDUBDfBIBU+PchBau7+cslEmUZAtNDle849b1eNIXWL6y37ggLw6D/hB5kE64NgCIFLwkUMEi2JW17dLWshBYZuJ4f1sRhJUZCRvRStxtnvYguBj/rrFeg6PQl2VA9PIz3A2KuvI7jNs+7cAZCmZqcoISCj0gvXLb59bYasvdh7uL/H++RpddpI0vlvRfHZ9qxPU8ByiexKoLGBKvF8hxiZlHngeXl/ZMNgsmCLxXwGvDKzXxFZbuisOc9ANcT6WjHEkQ32MjbaXc7ZBv8RRJYW6WKtbnNeUFrHfXbZ8bBFgcYwsbeV7JttnIJwjGwC07+YWvCxDzV8vh5Pm4xZ82GCznHaUYsQQgXz34jxoBgAXWHE3mLENKqQUImyNpxxycWqf8Q7TyvPUcr6XH7ndIlOLNF25FAFrXO8YEMNXbO+caLGWoyN/dtQA1xrSOAuIk+ILS012128IKfJYTg1ehpEskg8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ackerley Tng Update tdx_gmem_post_populate() to handle cases where userspace requests "no source page". To handle "no source page", populate (perform TDH.MEM.PAGE.ADD) using memory in-place at the target PFN. Allow "no source page" only when gmem_in_place_conversion is enabled, because retroactively adding support for out-of-place conversion would mean requiring a userspace update for a feature that's being deprecated. Also, KVM supporting "no source page" without in-place conversion would effectively be an obscure zero-page optimization that relies on the page being zeroed when it is allocated by guest_memfd. Rejecting "no source page" without in-place conversion scenario is valuable for KVM developers since it helps newcomers understand what exactly is and isn't possible. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Tested-by: Shivank Garg Reviewed-by: Binbin Wu Tested-by: Yan Zhao Reviewed-by: Yan Zhao Reviewed-by: Xiaoyao Li Signed-off-by: Ackerley Tng --- Documentation/virt/kvm/x86/intel-tdx.rst | 4 ++++ arch/x86/kvm/vmx/tdx.c | 8 +++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/Documentation/virt/kvm/x86/intel-tdx.rst b/Documentation/virt/kvm/x86/intel-tdx.rst index 6a222e9d09541..d8d9409120e61 100644 --- a/Documentation/virt/kvm/x86/intel-tdx.rst +++ b/Documentation/virt/kvm/x86/intel-tdx.rst @@ -158,6 +158,10 @@ KVM_TDX_INIT_MEM_REGION Initialize @nr_pages TDX guest private memory starting from @gpa with userspace provided data from @source_addr. @source_addr must be PAGE_SIZE-aligned. +If guest_memfd in-place conversion is enabled, pass 0 for @source_addr +to represent "no source page". A source page is required if in-place +conversion is not enabled or not supported. + Note, before calling this sub command, memory attribute of the range [gpa, gpa + nr_pages] needs to be private. Userspace can use KVM_SET_MEMORY_ATTRIBUTES to set the attribute. diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index b272c20586a74..7654a9f5fa128 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -3189,7 +3189,7 @@ static int tdx_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, if (KVM_BUG_ON(kvm_tdx->page_add_src, kvm)) return -EIO; - kvm_tdx->page_add_src = src_page; + kvm_tdx->page_add_src = src_page ?: pfn_to_page(pfn); ret = kvm_tdp_mmu_map_private_pfn(arg->vcpu, gfn, pfn); kvm_tdx->page_add_src = NULL; @@ -3235,7 +3235,8 @@ static int tdx_vcpu_init_mem_region(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *c if (copy_from_user(®ion, u64_to_user_ptr(cmd->data), sizeof(region))) return -EFAULT; - if (!PAGE_ALIGNED(region.source_addr) || !region.source_addr || + if (!PAGE_ALIGNED(region.source_addr) || + (!gmem_in_place_conversion && !region.source_addr) || !PAGE_ALIGNED(region.gpa) || !region.nr_pages || region.gpa + (region.nr_pages << PAGE_SHIFT) <= region.gpa || !vt_is_tdx_private_gpa(kvm, region.gpa) || @@ -3266,7 +3267,8 @@ static int tdx_vcpu_init_mem_region(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *c break; } - region.source_addr += PAGE_SIZE; + if (region.source_addr) + region.source_addr += PAGE_SIZE; region.gpa += PAGE_SIZE; region.nr_pages--; -- 2.55.0.897.gb25b4bd76c-goog