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AJvYcCWyxGuII/fVKbvaPfxCV6J8P7ghq8nTlgl8r726jmp3vPlNRaCA3BV5+IvmXZgpX0Cbh+YtXe2bjg==@kvack.org X-Gm-Message-State: AOJu0Yw9MiouCVAUPlGivarEBEE3jFikMvFt+612/fUET9ZkvtyweuhL /fGW7yo9owH2qytBpe/PcALOx/XxB3JqW3kcEmT3kTTn98VlZ0IktCFhOuBRU1DzT9e+P29ft3k pDMJUrz/+VnZryYzBRcW50k7iylD5cR8MKvMZ X-Gm-Gg: ASbGncsM/Hx2VpfUcTWEOGIkh9mKgMcaqooNvGEZTLk3qRgvKxx0ZjEE3cO/sC3UHk7 QWmO44ai5nZMKm7KrKlZKWWC3wDYTvSAoci9+oYOUu1yRWJen/Q1Qm1uWIgyjN7IqOw4asmlgrH e4ZX7jZNpxUKRecy7Kzy0CjT0hooEYL0eqvulw5SXdso29wq6KR7D06OA2 X-Google-Smtp-Source: AGHT+IEtSS+mpRhJKleMpaB3DbpAHfO3E4j/SkeoZwuqMVYrLHLfF7wB8kyvYfYSwwJ3d+GpQSCY5aetuJOZKgzlNfo= X-Received: by 2002:a05:6902:983:b0:e5e:700:92f5 with SMTP id 3f1490d57ef6-e635c1008c7mr2547657276.2.1741312417396; Thu, 06 Mar 2025 17:53:37 -0800 (PST) MIME-Version: 1.0 References: <20250303171013.3548775-1-tabba@google.com> <20250303171013.3548775-4-tabba@google.com> In-Reply-To: <20250303171013.3548775-4-tabba@google.com> From: James Houghton Date: Thu, 6 Mar 2025 17:53:01 -0800 X-Gm-Features: AQ5f1JrvF2iBlwi15PAxAXyxJXz24tpZUppjb6AWgrXV7KSzTqTZn53OQRuxcas Message-ID: Subject: Re: [PATCH v5 3/9] KVM: guest_memfd: Allow host to map guest_memfd() pages To: Fuad Tabba Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, peterx@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Stat-Signature: t4sh94ji1s5pcczu4zex5daj6z6fky9i X-Rspamd-Queue-Id: 80112100003 X-Rspam-User: X-HE-Tag: 1741312418-61984 X-HE-Meta: U2FsdGVkX18xTz4f2F0GkkvwMEpFW3ydU3PydPXIWqd31Iodapdmri1ATXY+A2xV0d9PnZievke+nuk5RyMsC9B6VTfssRJkGOxMYhcaef2LHoV+DCtmpr71UlOwfT1Otwkl+RmknbnLJ/98ChlCUzbnmi5x3XztDjLEOFiUH9PAgGuXNhqbbwf+W5TjUFn9ci3T8tKXLR3ruQFiXSJmN6AWwJ22OAG7Hi14QamyAeCelfprVHPzkcr6YQ2FMKLKURuCDsOTE42hrRk8kizYBkckQQQPIi27lcyz5H9bX7QN7FuMPVZSEUW3Ul8/1gC1Tv3/rFDC727050rmzRiT/RJ7FsUuRRZM+fhrQVamhI3fuw6clCE4bpAwPlL9Fi3mrvVDGMzc+SR2MEKHH4cxh/vZjS1nQ3QlDDl3xhM7MF9aioukg3OybmbTqnhteJVHBpX+KYaw7c1G5RlvtpR2fK8Rv+fW3QY7PDLUM/Bsjauj+is2wDRCe0+lx5oVMCfueDSBuhy2QUDNahZ7FexyQz6Ss/Aw5h7qBrM6NdsAo6BxMwK2OaZvHbdEnHglv6wrEQ7AyOMxiUvbcheLPGgfqw7OhSm3G16w+I+QyoQnjBidcHGITUKFrVZkYqqlew/9UJQVrG/FRl8OSxrZEmz3Pwb1heRdNDjtEfGKswE9EGPaT6HgIgqnHjYUuJsrPOsHw64DR2VeTXDPLtOixnWRps5swY84BFfFEILhJ7X/YwMclyfrf2kLdTNs+7HfZ4WzEVAEmj0LBgwKwdxkYOM0EIMtlBr22lLKFcDClTHESjSyQPLmpaHWBkYx3G1MdKg/oKyCTmLhzH9MQwAOTi4HBmsxi1xmRId4DMJJ2xgMfmubAFbgl80y4OyDJY0qTs9zv/gBDawy/itlrTgd5xiAecWk/qptzogj2SwBMCqgkoW8ZLTN6qmeOxAitW9/f9ytN827+iD6oq2/u+/gx5o oEkK4c4+ TKlZZD35aiW1FsiaE/6qOPfg4ET30iQKUUGMe2PS7yvv7r7i3ykks9qyMjD47DAWXl1NQJWjCDTYUXShsAbOUCJ1jIDGP5uYVSFpC3mXO0xv/WAA+Au/YxWcwJfs2d6l3YFi325d1u+GOuomsdHzXb/kIvz3rnoipwuwxmZWPB5F1tN6Aspmoqbf+S0Aa+3Ja+Ljxxo+95/mQNYOTIafuG0HnJcH63GhsuCus9RJyRhK5QYpaaAUzh3BIIeZK4D6V0/UC3Rdu5e1iKjccM9ioWI7FLMgCWaTqqNvq7NTs6U9E+35js95M8B54zDlxpXN2n55KVpi6y4zuTrvEwGSElYSkQg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.002410, 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 Mon, Mar 3, 2025 at 9:10=E2=80=AFAM Fuad Tabba wrote: > +static vm_fault_t kvm_gmem_fault(struct vm_fault *vmf) > +{ > + struct inode *inode =3D file_inode(vmf->vma->vm_file); > + struct folio *folio; > + vm_fault_t ret =3D VM_FAULT_LOCKED; > + > + filemap_invalidate_lock_shared(inode->i_mapping); > + > + folio =3D kvm_gmem_get_folio(inode, vmf->pgoff); > + if (IS_ERR(folio)) { > + switch (PTR_ERR(folio)) { > + case -EAGAIN: > + ret =3D VM_FAULT_RETRY; > + break; > + case -ENOMEM: > + ret =3D VM_FAULT_OOM; > + break; > + default: > + ret =3D VM_FAULT_SIGBUS; > + break; Tiny nit-pick: This smells almost like an open-coded vmf_error(). For the non-EAGAIN case, can we just call vmf_error()? > + } > + goto out_filemap; > + } > + > + if (folio_test_hwpoison(folio)) { > + ret =3D VM_FAULT_HWPOISON; > + goto out_folio; > + } > + > + /* Must be called with folio lock held, i.e., after kvm_gmem_get_= folio() */ > + if (!kvm_gmem_offset_is_shared(vmf->vma->vm_file, vmf->pgoff)) { > + ret =3D VM_FAULT_SIGBUS; > + goto out_folio; > + }