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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 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5B83FA000A X-Stat-Signature: 9og11qh3o8jk4b9gyg7yrwztc4rt67gf X-HE-Tag: 1786139578-746236 X-HE-Meta: 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 e0dYZxsM 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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: 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