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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=1694; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=RrmAu7ijt4T2BgV+VK4Wz6c8RsidOxZAmXDSW4OkVVw=; b=dSAQjeKmiLaKcZ3hz47vvakbuCRsgz9FVSQ5XqgaYCqPZV1uwCfGkSyysLvwAbEf1IHgLbigg mHLMql6CMxDAlFlXxnySZnQASx4VI9Do9ieGbBmxMLcQnNva9MvwGp/ 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: rspam08 X-Rspamd-Queue-Id: A7EA7180007 X-Stat-Signature: 356q4adkg955ete11yg3dmw7drpdrdut X-HE-Tag: 1789084547-237737 X-HE-Meta: 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 9XQywe3H 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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 Signed-off-by: Ackerley Tng Tested-by: Shivank Garg Reviewed-by: Fuad Tabba Reviewed-by: Xiaoyao Li Reviewed-by: Binbin Wu --- 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 75e03a2f79db2..c081e4b9b25de 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10637,14 +10637,15 @@ 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 -- 2.55.0.1007.g17ff1f9808-goog