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AJvYcCWtpWrrXSbGsWjW2mlRQPpDsTQV7LBfacyR4S0im6TWcAmXF3lALLrHLcEL54dxsYULnDZznzEjjRlG@lists.linux.dev X-Gm-Message-State: AOJu0YwDVeSXAEpHyZqCd6twq6uL4WqOds+Wbga7C6YhGmQ60CPV0HAv vrN9/4QZQkEONRiWeNgbr4rYYh4q11Id8WyStjGJdc1cyxuNiesZFaZYjzSv/mN234nDm+kxxOl RdO/rAQ== X-Received: from pgcv5.prod.google.com ([2002:a05:6a02:5305:b0:c73:9a1a:387d]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:3951:b0:39c:50b4:cd50 with SMTP id adf61e73a8af0-39f2f19b018mr622103637.61.1775172945555; Thu, 02 Apr 2026 16:35:45 -0700 (PDT) Date: Thu, 2 Apr 2026 16:35:44 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260319005605.8965-1-yan.y.zhao@intel.com> <20260319005703.8983-1-yan.y.zhao@intel.com> Message-ID: Subject: Re: [PATCH 1/2] x86/virt/tdx: Use PFN directly for mapping guest private memory From: Sean Christopherson To: Ackerley Tng Cc: Yan Zhao , pbonzini@redhat.com, dave.hansen@linux.intel.com, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, kas@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, kai.huang@intel.com, rick.p.edgecombe@intel.com, yilun.xu@linux.intel.com, vannapurve@google.com, sagis@google.com, binbin.wu@linux.intel.com, xiaoyao.li@intel.com, isaku.yamahata@intel.com Content-Type: text/plain; charset="us-ascii" On Thu, Apr 02, 2026, Ackerley Tng wrote: > Yan Zhao writes: > > > > > [...snip...] > > > > -u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, struct page *page, struct page *source, u64 *ext_err1, u64 *ext_err2) > > +u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, kvm_pfn_t pfn, struct page *source, > > + u64 *ext_err1, u64 *ext_err2) > > { > > struct tdx_module_args args = { > > .rcx = gpa, > > .rdx = tdx_tdr_pa(td), > > - .r8 = page_to_phys(page), > > + .r8 = PFN_PHYS(pfn), > > .r9 = page_to_phys(source), > > Perhaps in some future patch, are we considering also passing pfn instead of > struct page for source? Would we also update kvm_tdx->page_add_src to be a > kvm_pfn_t? Probably? I assume you're asking in the context of in-place conversion, where KVM will allow a single guest_memfd page to be both the source and the dest? Right now, KVM requires the source page to be a GUP'able page, specifically so that KVM can obtain a reference and ensure the page isn't freed until KVM is done with it. If/when the source and dest are one and the same, then I don't think we'd want to GUP the page (and there would be no need to since this would all run while holding gmem's filemap_invalidate_lock()), at which point, yeah, passing a "struct page" doesn't make much sense, and passing kvm_pfn_t or u64 or whatever seems like the obvious choice.