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AJvYcCUnltgpc+9n3pRKKfpD7dEDO13t80BxoRlfxjtrioudpcqVkYcs3VbFMglDMh3+f4LS9G6rPEvZTg==@kvack.org X-Gm-Message-State: AOJu0YxbdN5qaA0zhsBzzJZGmfYtH+ptIEw6Ot5DG8VmKSWctm7YlVih RrVcV0pWdc2J1uHjGmwTd4a2LwLMtP+SZBmzQGyKazVGySxrpRfW47hFmsJdHbHX/HBKfzUTmUk cbg/JkA== X-Received: from pllj12.prod.google.com ([2002:a17:902:758c:b0:29f:22e:147c]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1c2:b0:2a0:b461:c883 with SMTP id d9443c01a7336-2a599e2ed67mr4408825ad.45.1768342014462; Tue, 13 Jan 2026 14:06:54 -0800 (PST) Date: Tue, 13 Jan 2026 14:06:52 -0800 In-Reply-To: <20260113213556.rwihf3v3ek3c5kwl@amd.com> Mime-Version: 1.0 References: <20260108214622.1084057-1-michael.roth@amd.com> <20260108214622.1084057-7-michael.roth@amd.com> <20260113213556.rwihf3v3ek3c5kwl@amd.com> Message-ID: Subject: Re: [PATCH v3 6/6] KVM: guest_memfd: GUP source pages prior to populating guest memory From: Sean Christopherson To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, pbonzini@redhat.com, vbabka@suse.cz, ashish.kalra@amd.com, liam.merwick@oracle.com, david@redhat.com, vannapurve@google.com, ackerleytng@google.com, aik@amd.com, ira.weiny@intel.com, yan.y.zhao@intel.com, pankaj.gupta@amd.com, Kai Huang Content-Type: text/plain; charset="us-ascii" X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C039D4000C X-Stat-Signature: 33ygjxfh9u5ja881d4awixgqwo9ycx11 X-Rspam-User: X-HE-Tag: 1768342015-604615 X-HE-Meta: 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 UmuUJ6rO 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jan 13, 2026, Michael Roth wrote: > On Tue, Jan 13, 2026 at 11:21:29AM -0800, Sean Christopherson wrote: > > On Thu, Jan 08, 2026, Michael Roth wrote: > > > @@ -842,47 +881,38 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long > > > if (!file) > > > return -EFAULT; > > > > > > - filemap_invalidate_lock(file->f_mapping); > > > - > > > npages = min_t(ulong, slot->npages - (start_gfn - slot->base_gfn), npages); > > > for (i = 0; i < npages; i++) { > > > - struct folio *folio; > > > - gfn_t gfn = start_gfn + i; > > > - pgoff_t index = kvm_gmem_get_index(slot, gfn); > > > - kvm_pfn_t pfn; > > > + struct page *src_page = NULL; > > > + void __user *p; > > > > > > if (signal_pending(current)) { > > > ret = -EINTR; > > > break; > > > } > > > > > > - folio = __kvm_gmem_get_pfn(file, slot, index, &pfn, NULL); > > > - if (IS_ERR(folio)) { > > > - ret = PTR_ERR(folio); > > > - break; > > > - } > > > + p = src ? src + i * PAGE_SIZE : NULL; > > > > > > - folio_unlock(folio); > > > + if (p) { > > > > Computing 'p' when src==NULL is unnecessary and makes it hard to see that gup() > > is done if and only if src!=NULL. > > > > Anyone object to this fixup? > > No objections here, and it does seem a bit more readable. Will include > this if a new version is needed. No need, I'll fixup when applying (already have, actually). If you want to double check that I didn't fat finger anything, the patches are in kvm-x86/gmem. Thanks!