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Tue, 14 Feb 2023 10:07:29 -0800 (PST) Date: Tue, 14 Feb 2023 10:07:28 -0800 In-Reply-To: <20230213235343.GC4175971@ls.amr.corp.intel.com> Mime-Version: 1.0 References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-3-chao.p.peng@linux.intel.com> <20230209072529.GB4175971@ls.amr.corp.intel.com> <20230213235343.GC4175971@ls.amr.corp.intel.com> Message-ID: Subject: Re: [PATCH v10 2/9] KVM: Introduce per-page memory attributes From: Sean Christopherson To: Isaku Yamahata Cc: Chao Peng , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Arnd Bergmann , Naoya Horiguchi , Miaohe Lin , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Content-Type: text/plain; charset="us-ascii" X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7EA49120027 X-Rspam-User: X-Stat-Signature: 8j9ghi5bk55uqjbbyody1azr435rge8h X-HE-Tag: 1676398050-412388 X-HE-Meta: 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 cHyBfZFZ 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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: On Mon, Feb 13, 2023, Isaku Yamahata wrote: > On Fri, Feb 10, 2023 at 12:35:30AM +0000, > Sean Christopherson wrote: > > > On Wed, Feb 08, 2023, Isaku Yamahata wrote: > > > On Fri, Dec 02, 2022 at 02:13:40PM +0800, > > > Chao Peng wrote: > > > > > > > +static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm, > > > > + struct kvm_memory_attributes *attrs) > > > > +{ > > > > + gfn_t start, end; > > > > + unsigned long i; > > > > + void *entry; > > > > + u64 supported_attrs = kvm_supported_mem_attributes(kvm); > > > > + > > > > + /* flags is currently not used. */ > > > > + if (attrs->flags) > > > > + return -EINVAL; > > > > + if (attrs->attributes & ~supported_attrs) > > > > + return -EINVAL; > > > > + if (attrs->size == 0 || attrs->address + attrs->size < attrs->address) > > > > + return -EINVAL; > > > > + if (!PAGE_ALIGNED(attrs->address) || !PAGE_ALIGNED(attrs->size)) > > > > + return -EINVAL; > > > > + > > > > + start = attrs->address >> PAGE_SHIFT; > > > > + end = (attrs->address + attrs->size - 1 + PAGE_SIZE) >> PAGE_SHIFT; > > > > + > > > > + entry = attrs->attributes ? xa_mk_value(attrs->attributes) : NULL; > > > > + > > > > + mutex_lock(&kvm->lock); > > > > + for (i = start; i < end; i++) > > > > + if (xa_err(xa_store(&kvm->mem_attr_array, i, entry, > > > > + GFP_KERNEL_ACCOUNT))) > > > > + break; > > > > + mutex_unlock(&kvm->lock); > > > > + > > > > + attrs->address = i << PAGE_SHIFT; > > > > + attrs->size = (end - i) << PAGE_SHIFT; > > > > + > > > > + return 0; > > > > +} > > > > +#endif /* CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES */ > > > > + > > > > > > If memslot isn't private, it should return error if private attribute is set. > > > > Why? I'd rather keep the two things separate. If we enforce this sort of thing > > at KVM_SET_MEMORY_ATTRIBUTES, then we also have to enforce it at > > KVM_SET_USER_MEMORY_REGION. > > For device assignment via shared GPA, non-private memory slot needs to be > allowed. That doesn't say anything about why setting attributes needs to poke into the memslot. The page fault path already kicks out to userspace if there's a discrepancy between the attributes and the memslot, why is that insufficient?