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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, 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=1786139565; l=3323; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=fww/oL6aOL/zYOalPjjTEuFSWzNlNDgN26Nz/nDPoIw=; b=UsF5OWRfMfq1ob58hfueI4ABe8ND/ASl9ukTcTiCBDkuD3ck+A8QWQy8R4fap+euJOj80T6tM Dq4X1R9/FqCAxtgtlm6ZxM6W3dkxnpeNt8vBhyquk2Og3YAcaafiCzE 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-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4828F2000D X-Stat-Signature: 6kcrhg1tdqzjnyt1f9gnqcgij8hshaw7 X-Rspam-User: X-HE-Tag: 1786139576-437179 X-HE-Meta: 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 5pO1bVi7 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 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. Signed-off-by: Sean Christopherson Tested-by: Shivank Garg 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--; -- 2.55.0.654.g21b8a5bc05-goog