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bh=FPot4968BrrzY7lVw+wCqRSRqFOGaqVnuLbaco54t84=; b=pT1cKE5qo45twbYLFoifTHiRtxOTgBfSw8h/PmpQsnlghxeqA74ByQ0l7/JmSNZsH3jS0kwEA FZDy0ff5dwLBbaIcg7YIVPXmB7vme9WkWcqdC7GLxJMEVGO2PA4rqXh X-Mailer: b4 0.14.3 Message-ID: <20260326-gmem-inplace-conversion-v4-9-e202fe950ffd@google.com> Subject: [PATCH RFC v4 09/44] KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs From: Ackerley Tng 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, ira.weiny@intel.com, jmattson@google.com, jroedel@suse.de, 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, 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 , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Jason Gunthorpe , Vlastimil Babka 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, Ackerley Tng Content-Type: text/plain; charset="utf-8" X-Stat-Signature: szqr8nubr78bgf75crxqerkmthna6ums X-Rspamd-Queue-Id: 92423180007 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774563884-968567 X-HE-Meta: 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 9J4pTgqZ 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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 per-VM attributes are disabled, i.e. when it's actually possible for a guest_memfd instance to contain shared memory. Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7e133a9da11f0..9c29407712580 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -14056,14 +14056,13 @@ 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 isn't supported if the memory attributes are per-VM, + * in which case guest_memfd can _only_ be used for private memory. + */ + return !vm_memory_attributes || !kvm_arch_has_private_mem(kvm); } #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE -- 2.53.0.1018.g2bb0e51243-goog