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X-CSE-ConnectionGUID: 8FZFIA/VTOKBu7+Sy1N04g== X-CSE-MsgGUID: UnB9IzYOTWivtOvRrKtzlw== X-IronPort-AV: E=McAfee;i="6800,10657,11499"; a="54424867" X-IronPort-AV: E=Sophos;i="6.16,329,1744095600"; d="scan'208";a="54424867" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2025 07:27:30 -0700 X-CSE-ConnectionGUID: z23pwguhRCq0pG2C6uHt2g== X-CSE-MsgGUID: R04oqIF4Qc+jd/Sk1KqXag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,329,1744095600"; d="scan'208";a="162898084" Received: from yilunxu-optiplex-7050.sh.intel.com (HELO localhost) ([10.239.159.165]) by fmviesa003.fm.intel.com with ESMTP; 21 Jul 2025 07:27:11 -0700 Date: Mon, 21 Jul 2025 22:18:18 +0800 From: Xu Yilun To: Jason Gunthorpe Cc: Ackerley Tng , Yan Zhao , Vishal Annapurve , Alexey Kardashevskiy , Fuad Tabba , kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, ajones@ventanamicro.com, akpm@linux-foundation.org, amoorthy@google.com, anthony.yznaga@oracle.com, anup@brainfault.org, aou@eecs.berkeley.edu, bfoster@redhat.com, binbin.wu@linux.intel.com, brauner@kernel.org, catalin.marinas@arm.com, chao.p.peng@intel.com, chenhuacai@kernel.org, dave.hansen@intel.com, david@redhat.com, dmatlack@google.com, dwmw@amazon.co.uk, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, graf@amazon.com, haibo1.xu@intel.com, hch@infradead.org, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, kirill.shutemov@intel.com, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maz@kernel.org, mic@digikod.net, michael.roth@amd.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, pdurrant@amazon.co.uk, peterx@redhat.com, pgonda@google.com, pvorel@suse.cz, qperret@google.com, quic_cvanscha@quicinc.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, quic_svaddagi@quicinc.com, quic_tsoni@quicinc.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, thomas.lendacky@amd.com, usama.arif@bytedance.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, xiaoyao.li@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Subject: Re: [RFC PATCH v2 04/51] KVM: guest_memfd: Introduce KVM_GMEM_CONVERT_SHARED/PRIVATE ioctls Message-ID: References: <9502503f-e0c2-489e-99b0-94146f9b6f85@amd.com> <20250624130811.GB72557@ziepe.ca> <20250718141559.GF2206214@ziepe.ca> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250718141559.GF2206214@ziepe.ca> On Fri, Jul 18, 2025 at 11:15:59AM -0300, Jason Gunthorpe wrote: > On Fri, Jul 18, 2025 at 10:48:55AM +0800, Xu Yilun wrote: > > > If by the time KVM gets the conversion request, the page is unpinned, > > > then we're all good, right? > > > > Yes, unless guest doesn't unpin the page first by mistake. Guest would > > invoke a fw call tdg.mem.page.release to unpin the page before > > KVM_HC_MAP_GPA_RANGE. > > What does guest pinning mean? TDX firmware provides a mode, that host can't block the S-EPT mapping after TD accepts the mapping. Guest 'pins' the private mapping (KVM & IOMMU). TD should explicitly unaccept the page by tdg.mem.page.release, then host could successfully block/unmap the S-EPT. This is necessary when shared <-> private conversion. When TDX Connect is enabled, this mode is enforced. Thanks, Yilun > > Jason >