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Wed, 06 Sep 2023 15:10:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHp5n1WB8R1og/NcZaTM8SckALAeHpMUrTVBDu8TXyXcr3qI/pIRPsrfv30I89brgsoG52emGtevyCvY1jn784= X-Received: by 2002:a67:ee4d:0:b0:444:17aa:df60 with SMTP id g13-20020a67ee4d000000b0044417aadf60mr4110646vsp.13.1694038224758; Wed, 06 Sep 2023 15:10:24 -0700 (PDT) MIME-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-14-seanjc@google.com> <84a908ae-04c7-51c7-c9a8-119e1933a189@redhat.com> In-Reply-To: From: Paolo Bonzini Date: Thu, 7 Sep 2023 00:10:13 +0200 Message-ID: Subject: Re: [RFC PATCH v11 13/29] KVM: Add transparent hugepage support for dedicated guest memory To: Sean Christopherson Cc: Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: C126F1C0018 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: g9cpnpnfygu6xjbqgwsr8of3qdpnsh6q X-HE-Tag: 1694038227-968206 X-HE-Meta: U2FsdGVkX19XO+0mO1XHzUVS7a8nxkSvpLHh4Ih5+etbnwEnamdwclXb9z38c0z3zX9G11wLq2LHeLHvmmpTtw8nnbF1OTYjl7SnARVP0D1fu4nDNUPBS0NnfQvaqkRKI5c2Bb4M9ZESVMSer8+A6+uPNw1/b4ajcQMmMVs4LS9QtZ5lGJaXiMx5/OUILRNrdAW1CdKug0ShF0tl2s1gBK87Wziu4hgGRSQtpTHwS2ePfbt62914A3gTI5z/jLr2UBlebZFTJ2qvzEdxjJKdd4OpeJK6+1EDurmmzS1bvimJkf1TKCjzX5f8+mEIbD1v2XM7Jc0Swwt//Go5acxPTvl1Y32/rCcqH0nrbya4M5ijCsTsacgG0I9VmnBBYBQv5bC3Vg8nrKTUW+4ajGXEUzaPev+mI3nZ/le5NQU0Dd7YqHAsaZ5DJjOP4Tq9VZW/RlyPmi6lSZm791RtKbyhhYlKTNLnXP0KGNepMKrZ4KdtCOebzLGKMScZpbt2+CFU33kUvcZPTn6ix96L8Q56jLsnXAF+OjE/ZTVsteUUJ0RTB46IBjvnDk208kARCqfFrMicf8Pt6W4MITTUZuroNHAxc49nKHklvARH8iRYHwGJKKhBi18cCRU00rJVgM95kDKsRT8GEOxH7kiPnKDLb9qUyJsNjThusSk1CL2ZgCXE8Qoz4mlE0TKzDelOpUIwBVe+PpFos9Z3IibY0WpVGZCjbgsw4hCOHWHCbWChRMw0v8WLVSm7WRaDq5No+MsAmzCBvFBmXgJQ2IeQeOHIsttd150uocdERkBaEXLn4q+aNfF8GteegeLv9YhI8Afkaf2Z8hXjE0neH3eYMWSyLyQzGtw+qgNQuv2Jvfp8impIl7SJKd5GO420IuH5NMHaP5J83zCdv5T2MmaRQHeo+pVHEi9/Hx1a+hn3QESgX6cgL9mf7YpLBPd8u5OhhsundsCnYlzeuQuV8lTe/EU XJcUOIKr /FX5vlaO191ARy3cfFl1W9/vXNyZ6+Jtfu9g2XrDeHAmQ1+6Wj18/NTi4msFp2TBNLivPO0yBf6fiI/JfNV10sOFhv3xkPt8cVEhquCFBjHPzhosn7IJIgd3CQPjqO9/0tvDO2jzHTfZguqy1fSpll5wlKUUur8QjRoVAS6Awb+PhLVRkwAEos3VxLwTPGdk1kT5OTK+jrpPYBmnXS//HBCsWvpoB9jRV2Zqk62QiVUjvnvlX6tZfpYb5BkVLyM0y82x6It2hdrGWQmbGwpk0E9c+836DScg58lhHmYTyrlgdrUQ/OUtl695+MDx5i1+EO6qheE9vs/cy3r6GUkunwZ4lkQ== 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: On Fri, Jul 21, 2023 at 7:13=E2=80=AFPM Sean Christopherson wrote: > On Fri, Jul 21, 2023, Paolo Bonzini wrote: > > On 7/19/23 01:44, Sean Christopherson wrote: > > > @@ -413,6 +454,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_c= reate_guest_memfd *args) > > > u64 flags =3D args->flags; > > > u64 valid_flags =3D 0; > > > + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > > > + valid_flags |=3D KVM_GUEST_MEMFD_ALLOW_HUGEPAGE; > > > + > > > > I think it should be always allowed. The outcome would just be "never = have > > a hugepage" if thp is not enabled in the kernel. > > I don't have a strong preference. My thinking was that userspace would p= robably > rather have an explicit error, as opposed to silently running with a misc= onfigured > setup. Considering that is how madvise(MADV_HUGEPAGE) behaves, your patch is good. I disagree but consistency is better. Paolo