KVM: s390: use __kvm_faultin_pfn()
Refactor the existing page fault handling code to use __kvm_faultin_pfn(). This possible now that memslots are always present. Acked-by: Janosch Frank <frankja@linux.ibm.com> Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com> Link: https://lore.kernel.org/r/20250123144627.312456-7-imbrenda@linux.ibm.com Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Message-ID: <20250123144627.312456-7-imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda
parent
5cbe24350b
commit
3762e905ec
3 changed files with 106 additions and 27 deletions
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@ -4786,11 +4786,104 @@ static void kvm_s390_assert_primary_as(struct kvm_vcpu *vcpu)
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current->thread.gmap_int_code, current->thread.gmap_teid.val);
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}
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/*
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* __kvm_s390_handle_dat_fault() - handle a dat fault for the gmap of a vcpu
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* @vcpu: the vCPU whose gmap is to be fixed up
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* @gfn: the guest frame number used for memslots (including fake memslots)
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* @gaddr: the gmap address, does not have to match @gfn for ucontrol gmaps
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* @flags: FOLL_* flags
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*
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* Return: 0 on success, < 0 in case of error.
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* Context: The mm lock must not be held before calling. May sleep.
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*/
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int __kvm_s390_handle_dat_fault(struct kvm_vcpu *vcpu, gfn_t gfn, gpa_t gaddr, unsigned int flags)
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{
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struct kvm_memory_slot *slot;
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unsigned int fault_flags;
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bool writable, unlocked;
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unsigned long vmaddr;
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struct page *page;
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kvm_pfn_t pfn;
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int rc;
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slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
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if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
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return vcpu_post_run_addressing_exception(vcpu);
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fault_flags = flags & FOLL_WRITE ? FAULT_FLAG_WRITE : 0;
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if (vcpu->arch.gmap->pfault_enabled)
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flags |= FOLL_NOWAIT;
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vmaddr = __gfn_to_hva_memslot(slot, gfn);
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try_again:
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pfn = __kvm_faultin_pfn(slot, gfn, flags, &writable, &page);
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/* Access outside memory, inject addressing exception */
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if (is_noslot_pfn(pfn))
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return vcpu_post_run_addressing_exception(vcpu);
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/* Signal pending: try again */
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if (pfn == KVM_PFN_ERR_SIGPENDING)
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return -EAGAIN;
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/* Needs I/O, try to setup async pfault (only possible with FOLL_NOWAIT) */
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if (pfn == KVM_PFN_ERR_NEEDS_IO) {
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trace_kvm_s390_major_guest_pfault(vcpu);
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if (kvm_arch_setup_async_pf(vcpu))
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return 0;
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vcpu->stat.pfault_sync++;
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/* Could not setup async pfault, try again synchronously */
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flags &= ~FOLL_NOWAIT;
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goto try_again;
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}
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/* Any other error */
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if (is_error_pfn(pfn))
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return -EFAULT;
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/* Success */
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mmap_read_lock(vcpu->arch.gmap->mm);
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/* Mark the userspace PTEs as young and/or dirty, to avoid page fault loops */
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rc = fixup_user_fault(vcpu->arch.gmap->mm, vmaddr, fault_flags, &unlocked);
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if (!rc)
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rc = __gmap_link(vcpu->arch.gmap, gaddr, vmaddr);
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scoped_guard(spinlock, &vcpu->kvm->mmu_lock) {
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kvm_release_faultin_page(vcpu->kvm, page, false, writable);
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}
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mmap_read_unlock(vcpu->arch.gmap->mm);
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return rc;
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}
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static int vcpu_dat_fault_handler(struct kvm_vcpu *vcpu, unsigned long gaddr, unsigned int flags)
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{
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unsigned long gaddr_tmp;
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gfn_t gfn;
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gfn = gpa_to_gfn(gaddr);
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if (kvm_is_ucontrol(vcpu->kvm)) {
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/*
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* This translates the per-vCPU guest address into a
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* fake guest address, which can then be used with the
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* fake memslots that are identity mapping userspace.
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* This allows ucontrol VMs to use the normal fault
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* resolution path, like normal VMs.
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*/
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mmap_read_lock(vcpu->arch.gmap->mm);
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gaddr_tmp = __gmap_translate(vcpu->arch.gmap, gaddr);
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mmap_read_unlock(vcpu->arch.gmap->mm);
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if (gaddr_tmp == -EFAULT) {
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vcpu->run->exit_reason = KVM_EXIT_S390_UCONTROL;
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vcpu->run->s390_ucontrol.trans_exc_code = gaddr;
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vcpu->run->s390_ucontrol.pgm_code = PGM_SEGMENT_TRANSLATION;
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return -EREMOTE;
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}
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gfn = gpa_to_gfn(gaddr_tmp);
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}
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return __kvm_s390_handle_dat_fault(vcpu, gfn, gaddr, flags);
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}
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static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu)
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{
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unsigned int flags = 0;
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unsigned long gaddr;
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int rc = 0;
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gaddr = current->thread.gmap_teid.addr * PAGE_SIZE;
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if (kvm_s390_cur_gmap_fault_is_write())
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@ -4842,37 +4935,14 @@ static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu)
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case PGM_REGION_SECOND_TRANS:
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case PGM_REGION_THIRD_TRANS:
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kvm_s390_assert_primary_as(vcpu);
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if (vcpu->arch.gmap->pfault_enabled) {
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rc = gmap_fault(vcpu->arch.gmap, gaddr, flags | FAULT_FLAG_RETRY_NOWAIT);
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if (rc == -EFAULT)
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return vcpu_post_run_addressing_exception(vcpu);
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if (rc == -EAGAIN) {
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trace_kvm_s390_major_guest_pfault(vcpu);
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if (kvm_arch_setup_async_pf(vcpu))
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return 0;
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vcpu->stat.pfault_sync++;
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} else {
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return rc;
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}
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}
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rc = gmap_fault(vcpu->arch.gmap, gaddr, flags);
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if (rc == -EFAULT) {
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if (kvm_is_ucontrol(vcpu->kvm)) {
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vcpu->run->exit_reason = KVM_EXIT_S390_UCONTROL;
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vcpu->run->s390_ucontrol.trans_exc_code = gaddr;
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vcpu->run->s390_ucontrol.pgm_code = 0x10;
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return -EREMOTE;
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}
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return vcpu_post_run_addressing_exception(vcpu);
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}
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break;
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return vcpu_dat_fault_handler(vcpu, gaddr, flags);
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default:
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KVM_BUG(1, vcpu->kvm, "Unexpected program interrupt 0x%x, TEID 0x%016lx",
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current->thread.gmap_int_code, current->thread.gmap_teid.val);
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send_sig(SIGSEGV, current, 0);
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break;
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}
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return rc;
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return 0;
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}
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static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
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@ -5751,7 +5821,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
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}
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#endif
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case KVM_S390_VCPU_FAULT: {
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r = gmap_fault(vcpu->arch.gmap, arg, 0);
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idx = srcu_read_lock(&vcpu->kvm->srcu);
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r = vcpu_dat_fault_handler(vcpu, arg, 0);
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srcu_read_unlock(&vcpu->kvm->srcu, idx);
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break;
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}
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case KVM_ENABLE_CAP:
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@ -410,6 +410,12 @@ void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu);
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void kvm_s390_set_cpu_timer(struct kvm_vcpu *vcpu, __u64 cputm);
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__u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu);
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int kvm_s390_cpus_from_pv(struct kvm *kvm, u16 *rc, u16 *rrc);
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int __kvm_s390_handle_dat_fault(struct kvm_vcpu *vcpu, gfn_t gfn, gpa_t gaddr, unsigned int flags);
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static inline int kvm_s390_handle_dat_fault(struct kvm_vcpu *vcpu, gpa_t gaddr, unsigned int flags)
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{
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return __kvm_s390_handle_dat_fault(vcpu, gpa_to_gfn(gaddr), gaddr, flags);
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}
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/* implemented in diag.c */
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int kvm_s390_handle_diag(struct kvm_vcpu *vcpu);
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@ -605,6 +605,7 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
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radix_tree_preload_end();
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return rc;
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}
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EXPORT_SYMBOL(__gmap_link);
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/**
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* fixup_user_fault_nowait - manually resolve a user page fault without waiting
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