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Thu, 22 Feb 2024 08:11:35 -0800 (PST) Date: Thu, 22 Feb 2024 16:10:40 +0000 In-Reply-To: <20240222161047.402609-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240222161047.402609-1-tabba@google.com> X-Mailer: git-send-email 2.44.0.rc1.240.g4c46232300-goog Message-ID: <20240222161047.402609-20-tabba@google.com> Subject: [RFC PATCH v1 19/26] KVM: arm64: Handle guest_memfd()-backed guest page faults From: Fuad Tabba To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: 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, yu.c.zhang@linux.intel.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, tabba@google.com Introduce a new fault handler which responds to guest faults for guestmem pages. Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 75 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 72 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 6ad79390b15c..570b14da16b1 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1438,6 +1438,70 @@ static int insert_ppage(struct kvm *kvm, struct kvm_guest_page *ppage) return 0; } +static int guestmem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, + struct kvm_memory_slot *memslot) +{ + struct kvm_hyp_memcache *hyp_memcache = &vcpu->arch.pkvm_memcache; + struct kvm_guest_page *guest_page; + struct mm_struct *mm = current->mm; + gfn_t gfn = gpa_to_gfn(fault_ipa); + struct kvm *kvm = vcpu->kvm; + struct kvm_s2_mmu *mmu = &kvm->arch.mmu; + struct page *page = NULL; + kvm_pfn_t pfn; + int ret; + + ret = topup_hyp_memcache(hyp_memcache, kvm_mmu_cache_min_pages(mmu)); + if (ret) + return ret; + + /* + * Acquire the page lock to avoid racing with kvm_gmem_fault() when + * checking the page_mapcount later on. + */ + ret = kvm_gmem_get_pfn_locked(kvm, memslot, gfn, &pfn, NULL); + if (ret) + return ret; + + page = pfn_to_page(pfn); + + if (!kvm_gmem_is_mappable(kvm, gfn) && page_mapcount(page)) { + ret = -EPERM; + goto rel_page; + } + + guest_page = kmalloc(sizeof(*guest_page), GFP_KERNEL_ACCOUNT); + if (!guest_page) { + ret = -ENOMEM; + goto rel_page; + } + + guest_page->page = page; + guest_page->ipa = fault_ipa; + guest_page->is_pinned = false; + + ret = account_locked_vm(mm, 1, true); + if (ret) + goto free_gp; + + write_lock(&kvm->mmu_lock); + ret = pkvm_host_map_guest(pfn, gfn); + if (!ret) + WARN_ON(insert_ppage(kvm, guest_page)); + write_unlock(&kvm->mmu_lock); + + if (ret) + account_locked_vm(mm, 1, false); +free_gp: + if (ret) + kfree(guest_page); +rel_page: + unlock_page(page); + put_page(page); + + return ret != -EAGAIN ? ret : 0; +} + static int pkvm_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_memory_slot *memslot) { @@ -1887,11 +1951,16 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) goto out_unlock; } - if (is_protected_kvm_enabled()) - ret = pkvm_mem_abort(vcpu, fault_ipa, memslot); - else + if (is_protected_kvm_enabled()) { + if ((kvm_slot_can_be_private(memslot))) + ret = guestmem_abort(vcpu, fault_ipa, memslot); + else + ret = pkvm_mem_abort(vcpu, fault_ipa, memslot); + } else { ret = user_mem_abort(vcpu, fault_ipa, memslot, esr_fsc_is_permission_fault(esr)); + } + if (ret == 0) ret = 1;