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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=1789084533; l=3572; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=QQ75a+Dh+O5Bb+yAv7Loxc+5XdxMsQNqVi7/35Q15Qo=; b=akjC0UBBPebJpT/w6V0xNLQG0NczdDLezEKp4n0ly9NWVBSIXvgnLyF3dz99sbMsN70U0JSq0 DIlboWrv3dfBdxOeSw5hFgdrjCYir0bZ8HNby5/4rjpmJ5PxF3AuXAx 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: rspam05 X-Rspamd-Queue-Id: B51C240002 X-Stat-Signature: jo9shxazstzscdsyxojhjmjt5mxqfgiq X-Rspam-User: X-HE-Tag: 1789084546-301130 X-HE-Meta: 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 z2PEOYfm 3bZ/C8aCgh2cQJmUoaYETeKNegtyHGOFdHwXp1uzhtsW/5uSZR5QUk8g8WDEV/xVzaaSbph6bn9yiUMROkrDElIjXd0ekNQaFtQRELp6JTQJFbM5Gxalp/Sk1qde3Iqr9kxEfkvWT5QNQrBtbD9vQ4i/zJv6Q+MAYjWrh03Oi8hv/StJtNswaT1O/jONUZrxGmYeXDkNi7RES+XTP1/w7Ydqr7ZEgh322wHLf79xOi8c+BM3+ZLGLYw6cpLlFljNCdtU9Dn1AABcN/gMSn1aBY8KGaUxNNiLX9hJHyeX1W22F7BRIk3o2yxJ2C+mCCwCefdsiV1uB4gfVSkXlKL9glDKGOQ3cSuwMnPTUMLHIofW1tJF4vR9ff6DrwV7ti82fsgxLdshpdwZvyR4KFcFtyXmjPiesIBrDp7w9SxUUcQSLjPTJaTyYcwLm7OHcXZnSZv05gmXs+ls4by5X2trbjjKyask101Ju2tAjkY/1qM+GM2M1pQbcJKKsqqJ2yxld5CG47AqlJRKxHjkH6U1YEiRjMCouUEl3mMMzbTq0sszELko= 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 Signed-off-by: Ackerley Tng Tested-by: Shivank Garg Tested-by: Yan Zhao Reviewed-by: Binbin Wu Reviewed-by: Yan Zhao Reviewed-by: Xiaoyao Li --- 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--; -- 2.55.0.1007.g17ff1f9808-goog