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AJvYcCUHJBmg6/AKXI+r1+MWjkySOuFlcVYcy6VqO9lpuRdbQgd3/r2OoGWS/yA6d3d4uUnN+p2q/fA=@lists.linux.dev X-Gm-Message-State: AOJu0YyotsbPouCNt9vVTHOPd13bxW3l1aJIYbLKSx5bLC3+WfwztVaI qhzdGvg7T4Skrd54ByoZ4HRkkQtLyUZb2ql9n5aGKJMqaOQNtWRecQMYNycA3hTGr4AWFre5RBo bx187Bw== X-Received: from plss10.prod.google.com ([2002:a17:902:c64a:b0:29f:68b:3550]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:cf07:b0:2a2:bff6:42ef with SMTP id d9443c01a7336-2a7174fa860mr37848805ad.7.1768578064299; Fri, 16 Jan 2026 07:41:04 -0800 (PST) Date: Fri, 16 Jan 2026 07:41:02 -0800 In-Reply-To: <4781ba9c5d16394cdd785d008cf2a2d81c5cda35.camel@intel.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260114134510.1835-1-kalyazin@amazon.com> <20260114134510.1835-8-kalyazin@amazon.com> <208b151b-f458-4327-94bc-eb3f32d20a68@amazon.com> <4781ba9c5d16394cdd785d008cf2a2d81c5cda35.camel@intel.com> Message-ID: Subject: Re: [PATCH v9 07/13] KVM: guest_memfd: Add flag to remove from direct map From: Sean Christopherson To: Rick P Edgecombe Cc: "kalyazin@amazon.com" , "kalyazin@amazon.co.uk" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "kvmarm@lists.linux.dev" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "bpf@vger.kernel.org" , "loongarch@lists.linux.dev" , "linux-doc@vger.kernel.org" , "david@kernel.org" , "svens@linux.ibm.com" , "catalin.marinas@arm.com" , "palmer@dabbelt.com" , "jgross@suse.com" , "surenb@google.com" , "vbabka@suse.cz" , "riel@surriel.com" , "pfalcato@suse.de" , "x86@kernel.org" , "rppt@kernel.org" , "thuth@redhat.com" , "borntraeger@linux.ibm.com" , "maz@kernel.org" , "peterx@redhat.com" , "ast@kernel.org" , Vishal Annapurve , "pjw@kernel.org" , "alex@ghiti.fr" , "dave.hansen@linux.intel.com" , "tglx@linutronix.de" , "hca@linux.ibm.com" , "willy@infradead.org" , "wyihan@google.com" , "ryan.roberts@arm.com" , "yang@os.amperecomputing.com" , "jolsa@kernel.org" , "jmattson@google.com" , "luto@kernel.org" , "aneesh.kumar@kernel.org" , "haoluo@google.com" , "patrick.roy@linux.dev" , "akpm@linux-foundation.org" , "coxu@redhat.com" , "mhocko@suse.com" , "mlevitsk@redhat.com" , "jgg@ziepe.ca" , "hpa@zytor.com" , "song@kernel.org" , "Liam.Howlett@oracle.com" , "maobibo@loongson.cn" , "peterz@infradead.org" , "oupton@kernel.org" , "lorenzo.stoakes@oracle.com" , "jhubbard@nvidia.com" , "martin.lau@linux.dev" , "jthoughton@google.com" , "Jonathan.Cameron@huawei.com" , "Yu, Yu-cheng" , "eddyz87@gmail.com" , "yonghong.song@linux.dev" , "chenhuacai@kernel.org" , "shuah@kernel.org" , "prsampat@amd.com" , "kevin.brodsky@arm.com" , "shijie@os.amperecomputing.com" , "itazur@amazon.co.uk" , "suzuki.poulose@arm.com" , "pbonzini@redhat.com" , "dev.jain@arm.com" , "yuzenghui@huawei.com" , "gor@linux.ibm.com" , "jackabt@amazon.co.uk" , "daniel@iogearbox.net" , "agordeev@linux.ibm.com" , "andrii@kernel.org" , "mingo@redhat.com" , "aou@eecs.berkeley.edu" , "joey.gouly@arm.com" , "derekmn@amazon.com" , "xmarcalx@amazon.co.uk" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "jackmanb@google.com" , "bp@alien8.de" , "corbet@lwn.net" , "ackerleytng@google.com" , "jannh@google.com" , "john.fastabend@gmail.com" , "kas@kernel.org" , "will@kernel.org" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Fri, Jan 16, 2026, Rick P Edgecombe wrote: > On Fri, 2026-01-16 at 15:02 +0000, Nikita Kalyazin wrote: > > > TDX does some clearing at the direct map mapping for pages that > > > comes from gmem, using a special instruction. It also does some > > > clflushing at the direct map address for these pages. So I think we > > > need to make sure TDs don't pull from gmem fds with this flag. > >=20 > > Would you be able to give a pointer on how we can do that?=C2=A0 I'm no= t > > very familiar with the TDX code. >=20 > Uhh, that is a good question. Let me think. Pass @kvm to kvm_arch_gmem_supports_no_direct_map() and then return %false = if it's a TDX VM.