text: /*
   * kvm nested virtualization support for s390x
   *
   * Copyright IBM Corp. 2016
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License (version 2 only)
   * as published by the Free Software Foundation.
   *
   *    Author(s): David Hildenbrand <dahi@linux.vnet.ibm.com>
   */
  #include <linux/vmalloc.h>
  #include <linux/kvm_host.h>
  #include <linux/bug.h>
  #include <linux/list.h>
  #include <linux/bitmap.h>
  #include <linux/sched/signal.h>
  
  #include <asm/gmap.h>
  #include <asm/mmu_context.h>
  #include <asm/sclp.h>
  #include <asm/nmi.h>
  #include <asm/dis.h>
  #include "kvm-s390.h"
  #include "gaccess.h"
  
  struct vsie_page {
  	struct kvm_s390_sie_block scb_s;	/* 0x0000 */
  	/*
  	 * the backup info for machine check. ensure it's at
  	 * the same offset as that in struct sie_page!
  	 */
  	struct mcck_volatile_info mcck_info;    /* 0x0200 */
  	/*
  	 * The pinned original scb. Be aware that other VCPUs can modify
  	 * it while we read from it. Values that are used for conditions or
  	 * are reused conditionally, should be accessed via READ_ONCE.
  	 */
  	struct kvm_s390_sie_block *scb_o;	/* 0x0218 */
  	/* the shadow gmap in use by the vsie_page */
  	struct gmap *gmap;			/* 0x0220 */
  	/* address of the last reported fault to guest2 */
  	unsigned long fault_addr;		/* 0x0228 */
  	__u8 reserved[0x0700 - 0x0230];		/* 0x0230 */
  	struct kvm_s390_crypto_cb crycb;	/* 0x0700 */
  	__u8 fac[S390_ARCH_FAC_LIST_SIZE_BYTE];	/* 0x0800 */
  };
  
  /* trigger a validity icpt for the given scb */
  static int set_validity_icpt(struct kvm_s390_sie_block *scb,
  			     __u16 reason_code)
  {
  	scb->ipa = 0x1000;
  	scb->ipb = ((__u32) reason_code) << 16;
  	scb->icptcode = ICPT_VALIDITY;
  	return 1;
  }
  
  /* mark the prefix as unmapped, this will block the VSIE */
  static void prefix_unmapped(struct vsie_page *vsie_page)
  {
  	atomic_or(PROG_REQUEST, &vsie_page->scb_s.prog20);
  }
  
  /* mark the prefix as unmapped and wait until the VSIE has been left */
  static void prefix_unmapped_sync(struct vsie_page *vsie_page)
  {
  	prefix_unmapped(vsie_page);
  	if (vsie_page->scb_s.prog0c & PROG_IN_SIE)
  		atomic_or(CPUSTAT_STOP_INT, &vsie_page->scb_s.cpuflags);
  	while (vsie_page->scb_s.prog0c & PROG_IN_SIE)
  		cpu_relax();
  }
  
  /* mark the prefix as mapped, this will allow the VSIE to run */
  static void prefix_mapped(struct vsie_page *vsie_page)
  {
  	atomic_andnot(PROG_REQUEST, &vsie_page->scb_s.prog20);
  }
  
  /* test if the prefix is mapped into the gmap shadow */
  static int prefix_is_mapped(struct vsie_page *vsie_page)
  {
  	return !(atomic_read(&vsie_page->scb_s.prog20) & PROG_REQUEST);
  }
  
  /* copy the updated intervention request bits into the shadow scb */
  static void update_intervention_requests(struct vsie_page *vsie_page)
  {
  	const int bits = CPUSTAT_STOP_INT | CPUSTAT_IO_INT | CPUSTAT_EXT_INT;
  	int cpuflags;
  
  	cpuflags = atomic_read(&vsie_page->scb_o->cpuflags);
  	atomic_andnot(bits, &vsie_page->scb_s.cpuflags);
  	atomic_or(cpuflags & bits, &vsie_page->scb_s.cpuflags);
  }
  
  /* shadow (filter and validate) the cpuflags  */
  static int prepare_cpuflags(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	int newflags, cpuflags = atomic_read(&scb_o->cpuflags);
  
  	/* we don't allow ESA/390 guests */
  	if (!(cpuflags & CPUSTAT_ZARCH))
  		return set_validity_icpt(scb_s, 0x0001U);
  
  	if (cpuflags & (CPUSTAT_RRF | CPUSTAT_MCDS))
  		return set_validity_icpt(scb_s, 0x0001U);
  	else if (cpuflags & (CPUSTAT_SLSV | CPUSTAT_SLSR))
  		return set_validity_icpt(scb_s, 0x0007U);
  
  	/* intervention requests will be set later */
  	newflags = CPUSTAT_ZARCH;
  	if (cpuflags & CPUSTAT_GED && test_kvm_facility(vcpu->kvm, 8))
  		newflags |= CPUSTAT_GED;
  	if (cpuflags & CPUSTAT_GED2 && test_kvm_facility(vcpu->kvm, 78)) {
  		if (cpuflags & CPUSTAT_GED)
  			return set_validity_icpt(scb_s, 0x0001U);
  		newflags |= CPUSTAT_GED2;
  	}
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_GPERE))
  		newflags |= cpuflags & CPUSTAT_P;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_GSLS))
  		newflags |= cpuflags & CPUSTAT_SM;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_IBS))
  		newflags |= cpuflags & CPUSTAT_IBS;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_KSS))
  		newflags |= cpuflags & CPUSTAT_KSS;
  
  	atomic_set(&scb_s->cpuflags, newflags);
  	return 0;
  }
  
  /*
   * Create a shadow copy of the crycb block and setup key wrapping, if
   * requested for guest 3 and enabled for guest 2.
   *
   * We only accept format-1 (no AP in g2), but convert it into format-2
   * There is nothing to do for format-0.
   *
   * Returns: - 0 if shadowed or nothing to do
   *          - > 0 if control has to be given to guest 2
   */
  static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	const uint32_t crycbd_o = READ_ONCE(scb_o->crycbd);
  	const u32 crycb_addr = crycbd_o & 0x7ffffff8U;
  	unsigned long *b1, *b2;
  	u8 ecb3_flags;
  
  	scb_s->crycbd = 0;
  	if (!(crycbd_o & vcpu->arch.sie_block->crycbd & CRYCB_FORMAT1))
  		return 0;
  	/* format-1 is supported with message-security-assist extension 3 */
  	if (!test_kvm_facility(vcpu->kvm, 76))
  		return 0;
  	/* we may only allow it if enabled for guest 2 */
  	ecb3_flags = scb_o->ecb3 & vcpu->arch.sie_block->ecb3 &
  		     (ECB3_AES | ECB3_DEA);
  	if (!ecb3_flags)
  		return 0;
  
  	if ((crycb_addr & PAGE_MASK) != ((crycb_addr + 128) & PAGE_MASK))
  		return set_validity_icpt(scb_s, 0x003CU);
  	else if (!crycb_addr)
  		return set_validity_icpt(scb_s, 0x0039U);
  
  	/* copy only the wrapping keys */
  	if (read_guest_real(vcpu, crycb_addr + 72,
  			    vsie_page->crycb.dea_wrapping_key_mask, 56))
  		return set_validity_icpt(scb_s, 0x0035U);
  
  	scb_s->ecb3 |= ecb3_flags;
  	scb_s->crycbd = ((__u32)(__u64) &vsie_page->crycb) | CRYCB_FORMAT1 |
  			CRYCB_FORMAT2;
  
  	/* xor both blocks in one run */
  	b1 = (unsigned long *) vsie_page->crycb.dea_wrapping_key_mask;
  	b2 = (unsigned long *)
  			    vcpu->kvm->arch.crypto.crycb->dea_wrapping_key_mask;
  	/* as 56%8 == 0, bitmap_xor won't overwrite any data */
  	bitmap_xor(b1, b1, b2, BITS_PER_BYTE * 56);
  	return 0;
  }
  
  /* shadow (round up/down) the ibc to avoid validity icpt */
  static void prepare_ibc(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	/* READ_ONCE does not work on bitfields - use a temporary variable */
  	const uint32_t __new_ibc = scb_o->ibc;
  	const uint32_t new_ibc = READ_ONCE(__new_ibc) & 0x0fffU;
  	__u64 min_ibc = (sclp.ibc >> 16) & 0x0fffU;
  
  	scb_s->ibc = 0;
  	/* ibc installed in g2 and requested for g3 */
  	if (vcpu->kvm->arch.model.ibc && new_ibc) {
  		scb_s->ibc = new_ibc;
  		/* takte care of the minimum ibc level of the machine */
  		if (scb_s->ibc < min_ibc)
  			scb_s->ibc = min_ibc;
  		/* take care of the maximum ibc level set for the guest */
  		if (scb_s->ibc > vcpu->kvm->arch.model.ibc)
  			scb_s->ibc = vcpu->kvm->arch.model.ibc;
  	}
  }
  
  /* unshadow the scb, copying parameters back to the real scb */
  static void unshadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  
  	/* interception */
  	scb_o->icptcode = scb_s->icptcode;
  	scb_o->icptstatus = scb_s->icptstatus;
  	scb_o->ipa = scb_s->ipa;
  	scb_o->ipb = scb_s->ipb;
  	scb_o->gbea = scb_s->gbea;
  
  	/* timer */
  	scb_o->cputm = scb_s->cputm;
  	scb_o->ckc = scb_s->ckc;
  	scb_o->todpr = scb_s->todpr;
  
  	/* guest state */
  	scb_o->gpsw = scb_s->gpsw;
  	scb_o->gg14 = scb_s->gg14;
  	scb_o->gg15 = scb_s->gg15;
  	memcpy(scb_o->gcr, scb_s->gcr, 128);
  	scb_o->pp = scb_s->pp;
  
  	/* branch prediction */
  	if (test_kvm_facility(vcpu->kvm, 82)) {
  		scb_o->fpf &= ~FPF_BPBC;
  		scb_o->fpf |= scb_s->fpf & FPF_BPBC;
  	}
  
  	/* interrupt intercept */
  	switch (scb_s->icptcode) {
  	case ICPT_PROGI:
  	case ICPT_INSTPROGI:
  	case ICPT_EXTINT:
  		memcpy((void *)((u64)scb_o + 0xc0),
  		       (void *)((u64)scb_s + 0xc0), 0xf0 - 0xc0);
  		break;
  	case ICPT_PARTEXEC:
  		/* MVPG only */
  		memcpy((void *)((u64)scb_o + 0xc0),
  		       (void *)((u64)scb_s + 0xc0), 0xd0 - 0xc0);
  		break;
  	}
  
  	if (scb_s->ihcpu != 0xffffU)
  		scb_o->ihcpu = scb_s->ihcpu;
  }
  
  /*
   * Setup the shadow scb by copying and checking the relevant parts of the g2
   * provided scb.
   *
   * Returns: - 0 if the scb has been shadowed
   *          - > 0 if control has to be given to guest 2
   */
  static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	/* READ_ONCE does not work on bitfields - use a temporary variable */
  	const uint32_t __new_prefix = scb_o->prefix;
  	const uint32_t new_prefix = READ_ONCE(__new_prefix);
  	const bool wants_tx = READ_ONCE(scb_o->ecb) & ECB_TE;
  	bool had_tx = scb_s->ecb & ECB_TE;
  	unsigned long new_mso = 0;
  	int rc;
  
  	/* make sure we don't have any leftovers when reusing the scb */
  	scb_s->icptcode = 0;
  	scb_s->eca = 0;
  	scb_s->ecb = 0;
  	scb_s->ecb2 = 0;
  	scb_s->ecb3 = 0;
  	scb_s->ecd = 0;
  	scb_s->fac = 0;
  	scb_s->fpf = 0;
  
  	rc = prepare_cpuflags(vcpu, vsie_page);
  	if (rc)
  		goto out;
  
  	/* timer */
  	scb_s->cputm = scb_o->cputm;
  	scb_s->ckc = scb_o->ckc;
  	scb_s->todpr = scb_o->todpr;
  	scb_s->epoch = scb_o->epoch;
  
  	/* guest state */
  	scb_s->gpsw = scb_o->gpsw;
  	scb_s->gg14 = scb_o->gg14;
  	scb_s->gg15 = scb_o->gg15;
  	memcpy(scb_s->gcr, scb_o->gcr, 128);
  	scb_s->pp = scb_o->pp;
  
  	/* interception / execution handling */
  	scb_s->gbea = scb_o->gbea;
  	scb_s->lctl = scb_o->lctl;
  	scb_s->svcc = scb_o->svcc;
  	scb_s->ictl = scb_o->ictl;
  	/*
  	 * SKEY handling functions can't deal with false setting of PTE invalid
  	 * bits. Therefore we cannot provide interpretation and would later
  	 * have to provide own emulation handlers.
  	 */
  	if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_KSS))
  		scb_s->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
  
  	scb_s->icpua = scb_o->icpua;
  
  	if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_SM))
  		new_mso = READ_ONCE(scb_o->mso) & 0xfffffffffff00000UL;
  	/* if the hva of the prefix changes, we have to remap the prefix */
  	if (scb_s->mso != new_mso || scb_s->prefix != new_prefix)
  		prefix_unmapped(vsie_page);
  	 /* SIE will do mso/msl validity and exception checks for us */
  	scb_s->msl = scb_o->msl & 0xfffffffffff00000UL;
  	scb_s->mso = new_mso;
  	scb_s->prefix = new_prefix;
  
  	/* We have to definetly flush the tlb if this scb never ran */
  	if (scb_s->ihcpu != 0xffffU)
  		scb_s->ihcpu = scb_o->ihcpu;
  
  	/* MVPG and Protection Exception Interpretation are always available */
  	scb_s->eca |= scb_o->eca & (ECA_MVPGI | ECA_PROTEXCI);
  	/* Host-protection-interruption introduced with ESOP */
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_ESOP))
  		scb_s->ecb |= scb_o->ecb & ECB_HOSTPROTINT;
  	/* transactional execution */
  	if (test_kvm_facility(vcpu->kvm, 73) && wants_tx) {
  		/* remap the prefix is tx is toggled on */
  		if (!had_tx)
  			prefix_unmapped(vsie_page);
  		scb_s->ecb |= ECB_TE;
  	}
  	/* branch prediction */
  	if (test_kvm_facility(vcpu->kvm, 82))
  		scb_s->fpf |= scb_o->fpf & FPF_BPBC;
  	/* SIMD */
  	if (test_kvm_facility(vcpu->kvm, 129)) {
  		scb_s->eca |= scb_o->eca & ECA_VX;
  		scb_s->ecd |= scb_o->ecd & ECD_HOSTREGMGMT;
  	}
  	/* Run-time-Instrumentation */
  	if (test_kvm_facility(vcpu->kvm, 64))
  		scb_s->ecb3 |= scb_o->ecb3 & ECB3_RI;
  	/* Instruction Execution Prevention */
  	if (test_kvm_facility(vcpu->kvm, 130))
  		scb_s->ecb2 |= scb_o->ecb2 & ECB2_IEP;
  	/* Guarded Storage */
  	if (test_kvm_facility(vcpu->kvm, 133)) {
  		scb_s->ecb |= scb_o->ecb & ECB_GS;
  		scb_s->ecd |= scb_o->ecd & ECD_HOSTREGMGMT;
  	}
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_SIIF))
  		scb_s->eca |= scb_o->eca & ECA_SII;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_IB))
  		scb_s->eca |= scb_o->eca & ECA_IB;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_CEI))
  		scb_s->eca |= scb_o->eca & ECA_CEI;
  	/* Epoch Extension */
  	if (test_kvm_facility(vcpu->kvm, 139))
  		scb_s->ecd |= scb_o->ecd & ECD_MEF;
  
  	prepare_ibc(vcpu, vsie_page);
  	rc = shadow_crycb(vcpu, vsie_page);
  out:
  	if (rc)
  		unshadow_scb(vcpu, vsie_page);
  	return rc;
  }
  
  void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start,
  				 unsigned long end)
  {
  	struct kvm *kvm = gmap->private;
  	struct vsie_page *cur;
  	unsigned long prefix;
  	struct page *page;
  	int i;
  
  	if (!gmap_is_shadow(gmap))
  		return;
  	if (start >= 1UL << 31)
  		/* We are only interested in prefix pages */
  		return;
  
  	/*
  	 * Only new shadow blocks are added to the list during runtime,
  	 * therefore we can safely reference them all the time.
  	 */
  	for (i = 0; i < kvm->arch.vsie.page_count; i++) {
  		page = READ_ONCE(kvm->arch.vsie.pages[i]);
  		if (!page)
  			continue;
  		cur = page_to_virt(page);
  		if (READ_ONCE(cur->gmap) != gmap)
  			continue;
  		prefix = cur->scb_s.prefix << GUEST_PREFIX_SHIFT;
  		/* with mso/msl, the prefix lies at an offset */
  		prefix += cur->scb_s.mso;
  		if (prefix <= end && start <= prefix + 2 * PAGE_SIZE - 1)
  			prefix_unmapped_sync(cur);
  	}
  }
  
  /*
   * Map the first prefix page and if tx is enabled also the second prefix page.
   *
   * The prefix will be protected, a gmap notifier will inform about unmaps.
   * The shadow scb must not be executed until the prefix is remapped, this is
   * guaranteed by properly handling PROG_REQUEST.
   *
   * Returns: - 0 on if successfully mapped or already mapped
   *          - > 0 if control has to be given to guest 2
   *          - -EAGAIN if the caller can retry immediately
   *          - -ENOMEM if out of memory
   */
  static int map_prefix(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	u64 prefix = scb_s->prefix << GUEST_PREFIX_SHIFT;
  	int rc;
  
  	if (prefix_is_mapped(vsie_page))
  		return 0;
  
  	/* mark it as mapped so we can catch any concurrent unmappers */
  	prefix_mapped(vsie_page);
  
  	/* with mso/msl, the prefix lies at offset *mso* */
  	prefix += scb_s->mso;
  
  	rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap, prefix);
  	if (!rc && (scb_s->ecb & ECB_TE))
  		rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
  					   prefix + PAGE_SIZE);
  	/*
  	 * We don't have to mprotect, we will be called for all unshadows.
  	 * SIE will detect if protection applies and trigger a validity.
  	 */
  	if (rc)
  		prefix_unmapped(vsie_page);
  	if (rc > 0 || rc == -EFAULT)
  		rc = set_validity_icpt(scb_s, 0x0037U);
  	return rc;
  }
  
  /*
   * Pin the guest page given by gpa and set hpa to the pinned host address.
   * Will always be pinned writable.
   *
   * Returns: - 0 on success
   *          - -EINVAL if the gpa is not valid guest storage
   *          - -ENOMEM if out of memory
   */
  static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
  {
  	struct page *page;
  	hva_t hva;
  	int rc;
  
  	hva = gfn_to_hva(kvm, gpa_to_gfn(gpa));
  	if (kvm_is_error_hva(hva))
  		return -EINVAL;
  	rc = get_user_pages_fast(hva, 1, 1, &page);
  	if (rc < 0)
  		return rc;
  	else if (rc != 1)
  		return -ENOMEM;
  	*hpa = (hpa_t) page_to_virt(page) + (gpa & ~PAGE_MASK);
  	return 0;
  }
  
  /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
  static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
  {
  	struct page *page;
  
  	page = virt_to_page(hpa);
  	set_page_dirty_lock(page);
  	put_page(page);
  	/* mark the page always as dirty for migration */
  	mark_page_dirty(kvm, gpa_to_gfn(gpa));
  }
  
  /* unpin all blocks previously pinned by pin_blocks(), marking them dirty */
  static void unpin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	hpa_t hpa;
  	gpa_t gpa;
  
  	hpa = (u64) scb_s->scaoh << 32 | scb_s->scaol;
  	if (hpa) {
  		gpa = scb_o->scaol & ~0xfUL;
  		if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_64BSCAO))
  			gpa |= (u64) scb_o->scaoh << 32;
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  		scb_s->scaol = 0;
  		scb_s->scaoh = 0;
  	}
  
  	hpa = scb_s->itdba;
  	if (hpa) {
  		gpa = scb_o->itdba & ~0xffUL;
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  		scb_s->itdba = 0;
  	}
  
  	hpa = scb_s->gvrd;
  	if (hpa) {
  		gpa = scb_o->gvrd & ~0x1ffUL;
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  		scb_s->gvrd = 0;
  	}
  
  	hpa = scb_s->riccbd;
  	if (hpa) {
  		gpa = scb_o->riccbd & ~0x3fUL;
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  		scb_s->riccbd = 0;
  	}
  
  	hpa = scb_s->sdnxo;
  	if (hpa) {
  		gpa = scb_o->sdnxo;
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  		scb_s->sdnxo = 0;
  	}
  }
  
  /*
   * Instead of shadowing some blocks, we can simply forward them because the
   * addresses in the scb are 64 bit long.
   *
   * This works as long as the data lies in one page. If blocks ever exceed one
   * page, we have to fall back to shadowing.
   *
   * As we reuse the sca, the vcpu pointers contained in it are invalid. We must
   * therefore not enable any facilities that access these pointers (e.g. SIGPIF).
   *
   * Returns: - 0 if all blocks were pinned.
   *          - > 0 if control has to be given to guest 2
   *          - -ENOMEM if out of memory
   */
  static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	hpa_t hpa;
  	gpa_t gpa;
  	int rc = 0;
  
  	gpa = READ_ONCE(scb_o->scaol) & ~0xfUL;
  	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_64BSCAO))
  		gpa |= (u64) READ_ONCE(scb_o->scaoh) << 32;
  	if (gpa) {
  		if (!(gpa & ~0x1fffUL))
  			rc = set_validity_icpt(scb_s, 0x0038U);
  		else if ((gpa & ~0x1fffUL) == kvm_s390_get_prefix(vcpu))
  			rc = set_validity_icpt(scb_s, 0x0011U);
  		else if ((gpa & PAGE_MASK) !=
  			 ((gpa + sizeof(struct bsca_block) - 1) & PAGE_MASK))
  			rc = set_validity_icpt(scb_s, 0x003bU);
  		if (!rc) {
  			rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  			if (rc == -EINVAL)
  				rc = set_validity_icpt(scb_s, 0x0034U);
  		}
  		if (rc)
  			goto unpin;
  		scb_s->scaoh = (u32)((u64)hpa >> 32);
  		scb_s->scaol = (u32)(u64)hpa;
  	}
  
  	gpa = READ_ONCE(scb_o->itdba) & ~0xffUL;
  	if (gpa && (scb_s->ecb & ECB_TE)) {
  		if (!(gpa & ~0x1fffUL)) {
  			rc = set_validity_icpt(scb_s, 0x0080U);
  			goto unpin;
  		}
  		/* 256 bytes cannot cross page boundaries */
  		rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  		if (rc == -EINVAL)
  			rc = set_validity_icpt(scb_s, 0x0080U);
  		if (rc)
  			goto unpin;
  		scb_s->itdba = hpa;
  	}
  
  	gpa = READ_ONCE(scb_o->gvrd) & ~0x1ffUL;
  	if (gpa && (scb_s->eca & ECA_VX) && !(scb_s->ecd & ECD_HOSTREGMGMT)) {
  		if (!(gpa & ~0x1fffUL)) {
  			rc = set_validity_icpt(scb_s, 0x1310U);
  			goto unpin;
  		}
  		/*
  		 * 512 bytes vector registers cannot cross page boundaries
  		 * if this block gets bigger, we have to shadow it.
  		 */
  		rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  		if (rc == -EINVAL)
  			rc = set_validity_icpt(scb_s, 0x1310U);
  		if (rc)
  			goto unpin;
  		scb_s->gvrd = hpa;
  	}
  
  	gpa = READ_ONCE(scb_o->riccbd) & ~0x3fUL;
  	if (gpa && (scb_s->ecb3 & ECB3_RI)) {
  		if (!(gpa & ~0x1fffUL)) {
  			rc = set_validity_icpt(scb_s, 0x0043U);
  			goto unpin;
  		}
  		/* 64 bytes cannot cross page boundaries */
  		rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  		if (rc == -EINVAL)
  			rc = set_validity_icpt(scb_s, 0x0043U);
  		/* Validity 0x0044 will be checked by SIE */
  		if (rc)
  			goto unpin;
  		scb_s->riccbd = hpa;
  	}
  	if ((scb_s->ecb & ECB_GS) && !(scb_s->ecd & ECD_HOSTREGMGMT)) {
  		unsigned long sdnxc;
  
  		gpa = READ_ONCE(scb_o->sdnxo) & ~0xfUL;
  		sdnxc = READ_ONCE(scb_o->sdnxo) & 0xfUL;
  		if (!gpa || !(gpa & ~0x1fffUL)) {
  			rc = set_validity_icpt(scb_s, 0x10b0U);
  			goto unpin;
  		}
  		if (sdnxc < 6 || sdnxc > 12) {
  			rc = set_validity_icpt(scb_s, 0x10b1U);
  			goto unpin;
  		}
  		if (gpa & ((1 << sdnxc) - 1)) {
  			rc = set_validity_icpt(scb_s, 0x10b2U);
  			goto unpin;
  		}
  		/* Due to alignment rules (checked above) this cannot
  		 * cross page boundaries
  		 */
  		rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  		if (rc == -EINVAL)
  			rc = set_validity_icpt(scb_s, 0x10b0U);
  		if (rc)
  			goto unpin;
  		scb_s->sdnxo = hpa | sdnxc;
  	}
  	return 0;
  unpin:
  	unpin_blocks(vcpu, vsie_page);
  	return rc;
  }
  
  /* unpin the scb provided by guest 2, marking it as dirty */
  static void unpin_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page,
  		      gpa_t gpa)
  {
  	hpa_t hpa = (hpa_t) vsie_page->scb_o;
  
  	if (hpa)
  		unpin_guest_page(vcpu->kvm, gpa, hpa);
  	vsie_page->scb_o = NULL;
  }
  
  /*
   * Pin the scb at gpa provided by guest 2 at vsie_page->scb_o.
   *
   * Returns: - 0 if the scb was pinned.
   *          - > 0 if control has to be given to guest 2
   *          - -ENOMEM if out of memory
   */
  static int pin_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page,
  		   gpa_t gpa)
  {
  	hpa_t hpa;
  	int rc;
  
  	rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
  	if (rc == -EINVAL) {
  		rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
  		if (!rc)
  			rc = 1;
  	}
  	if (!rc)
  		vsie_page->scb_o = (struct kvm_s390_sie_block *) hpa;
  	return rc;
  }
  
  /*
   * Inject a fault into guest 2.
   *
   * Returns: - > 0 if control has to be given to guest 2
   *            < 0 if an error occurred during injection.
   */
  static int inject_fault(struct kvm_vcpu *vcpu, __u16 code, __u64 vaddr,
  			bool write_flag)
  {
  	struct kvm_s390_pgm_info pgm = {
  		.code = code,
  		.trans_exc_code =
  			/* 0-51: virtual address */
  			(vaddr & 0xfffffffffffff000UL) |
  			/* 52-53: store / fetch */
  			(((unsigned int) !write_flag) + 1) << 10,
  			/* 62-63: asce id (alway primary == 0) */
  		.exc_access_id = 0, /* always primary */
  		.op_access_id = 0, /* not MVPG */
  	};
  	int rc;
  
  	if (code == PGM_PROTECTION)
  		pgm.trans_exc_code |= 0x4UL;
  
  	rc = kvm_s390_inject_prog_irq(vcpu, &pgm);
  	return rc ? rc : 1;
  }
  
  /*
   * Handle a fault during vsie execution on a gmap shadow.
   *
   * Returns: - 0 if the fault was resolved
   *          - > 0 if control has to be given to guest 2
   *          - < 0 if an error occurred
   */
  static int handle_fault(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	int rc;
  
  	if (current->thread.gmap_int_code == PGM_PROTECTION)
  		/* we can directly forward all protection exceptions */
  		return inject_fault(vcpu, PGM_PROTECTION,
  				    current->thread.gmap_addr, 1);
  
  	rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
  				   current->thread.gmap_addr);
  	if (rc > 0) {
  		rc = inject_fault(vcpu, rc,
  				  current->thread.gmap_addr,
  				  current->thread.gmap_write_flag);
  		if (rc >= 0)
  			vsie_page->fault_addr = current->thread.gmap_addr;
  	}
  	return rc;
  }
  
  /*
   * Retry the previous fault that required guest 2 intervention. This avoids
   * one superfluous SIE re-entry and direct exit.
   *
   * Will ignore any errors. The next SIE fault will do proper fault handling.
   */
  static void handle_last_fault(struct kvm_vcpu *vcpu,
  			      struct vsie_page *vsie_page)
  {
  	if (vsie_page->fault_addr)
  		kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
  				      vsie_page->fault_addr);
  	vsie_page->fault_addr = 0;
  }
  
  static inline void clear_vsie_icpt(struct vsie_page *vsie_page)
  {
  	vsie_page->scb_s.icptcode = 0;
  }
  
  /* rewind the psw and clear the vsie icpt, so we can retry execution */
  static void retry_vsie_icpt(struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	int ilen = insn_length(scb_s->ipa >> 8);
  
  	/* take care of EXECUTE instructions */
  	if (scb_s->icptstatus & 1) {
  		ilen = (scb_s->icptstatus >> 4) & 0x6;
  		if (!ilen)
  			ilen = 4;
  	}
  	scb_s->gpsw.addr = __rewind_psw(scb_s->gpsw, ilen);
  	clear_vsie_icpt(vsie_page);
  }
  
  /*
   * Try to shadow + enable the guest 2 provided facility list.
   * Retry instruction execution if enabled for and provided by guest 2.
   *
   * Returns: - 0 if handled (retry or guest 2 icpt)
   *          - > 0 if control has to be given to guest 2
   */
  static int handle_stfle(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	__u32 fac = READ_ONCE(vsie_page->scb_o->fac) & 0x7ffffff8U;
  
  	if (fac && test_kvm_facility(vcpu->kvm, 7)) {
  		retry_vsie_icpt(vsie_page);
  		if (read_guest_real(vcpu, fac, &vsie_page->fac,
  				    sizeof(vsie_page->fac)))
  			return set_validity_icpt(scb_s, 0x1090U);
  		scb_s->fac = (__u32)(__u64) &vsie_page->fac;
  	}
  	return 0;
  }
  
  /*
   * Run the vsie on a shadow scb and a shadow gmap, without any further
   * sanity checks, handling SIE faults.
   *
   * Returns: - 0 everything went fine
   *          - > 0 if control has to be given to guest 2
   *          - < 0 if an error occurred
   */
  static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
  	int guest_bp_isolation;
  	int rc;
  
  	handle_last_fault(vcpu, vsie_page);
  
  	if (need_resched())
  		schedule();
  	if (test_cpu_flag(CIF_MCCK_PENDING))
  		s390_handle_mcck();
  
  	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
  
  	/* save current guest state of bp isolation override */
  	guest_bp_isolation = test_thread_flag(TIF_ISOLATE_BP_GUEST);
  
  	/*
  	 * The guest is running with BPBC, so we have to force it on for our
  	 * nested guest. This is done by enabling BPBC globally, so the BPBC
  	 * control in the SCB (which the nested guest can modify) is simply
  	 * ignored.
  	 */
  	if (test_kvm_facility(vcpu->kvm, 82) &&
  	    vcpu->arch.sie_block->fpf & FPF_BPBC)
  		set_thread_flag(TIF_ISOLATE_BP_GUEST);
  
  	local_irq_disable();
  	guest_enter_irqoff();
  	local_irq_enable();
  
  	rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
  
  	local_irq_disable();
  	guest_exit_irqoff();
  	local_irq_enable();
  
  	/* restore guest state for bp isolation override */
  	if (!guest_bp_isolation)
  		clear_thread_flag(TIF_ISOLATE_BP_GUEST);
  
  	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
  
  	if (rc == -EINTR) {
  		VCPU_EVENT(vcpu, 3, "%s", "machine check");
  		kvm_s390_reinject_machine_check(vcpu, &vsie_page->mcck_info);
  		return 0;
  	}
  
  	if (rc > 0)
  		rc = 0; /* we could still have an icpt */
  	else if (rc == -EFAULT)
  		return handle_fault(vcpu, vsie_page);
  
  	switch (scb_s->icptcode) {
  	case ICPT_INST:
  		if (scb_s->ipa == 0xb2b0)
  			rc = handle_stfle(vcpu, vsie_page);
  		break;
  	case ICPT_STOP:
  		/* stop not requested by g2 - must have been a kick */
  		if (!(atomic_read(&scb_o->cpuflags) & CPUSTAT_STOP_INT))
  			clear_vsie_icpt(vsie_page);
  		break;
  	case ICPT_VALIDITY:
  		if ((scb_s->ipa & 0xf000) != 0xf000)
  			scb_s->ipa += 0x1000;
  		break;
  	}
  	return rc;
  }
  
  static void release_gmap_shadow(struct vsie_page *vsie_page)
  {
  	if (vsie_page->gmap)
  		gmap_put(vsie_page->gmap);
  	WRITE_ONCE(vsie_page->gmap, NULL);
  	prefix_unmapped(vsie_page);
  }
  
  static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
  			       struct vsie_page *vsie_page)
  {
  	unsigned long asce;
  	union ctlreg0 cr0;
  	struct gmap *gmap;
  	int edat;
  
  	asce = vcpu->arch.sie_block->gcr[1];
  	cr0.val = vcpu->arch.sie_block->gcr[0];
  	edat = cr0.edat && test_kvm_facility(vcpu->kvm, 8);
  	edat += edat && test_kvm_facility(vcpu->kvm, 78);
  
  	/*
  	 * ASCE or EDAT could have changed since last icpt, or the gmap
  	 * we're holding has been unshadowed. If the gmap is still valid,
  	 * we can safely reuse it.
  	 */
  	if (vsie_page->gmap && gmap_shadow_valid(vsie_page->gmap, asce, edat))
  		return 0;
  
  	/* release the old shadow - if any, and mark the prefix as unmapped */
  	release_gmap_shadow(vsie_page);
  	gmap = gmap_shadow(vcpu->arch.gmap, asce, edat);
  	if (IS_ERR(gmap))
  		return PTR_ERR(gmap);
  	gmap->private = vcpu->kvm;
  	WRITE_ONCE(vsie_page->gmap, gmap);
  	return 0;
  }
  
  /*
   * Register the shadow scb at the VCPU, e.g. for kicking out of vsie.
   */
  static void register_shadow_scb(struct kvm_vcpu *vcpu,
  				struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  
  	WRITE_ONCE(vcpu->arch.vsie_block, &vsie_page->scb_s);
  	/*
  	 * External calls have to lead to a kick of the vcpu and
  	 * therefore the vsie -> Simulate Wait state.
  	 */
  	atomic_or(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
  	/*
  	 * We have to adjust the g3 epoch by the g2 epoch. The epoch will
  	 * automatically be adjusted on tod clock changes via kvm_sync_clock.
  	 */
  	preempt_disable();
  	scb_s->epoch += vcpu->kvm->arch.epoch;
  
  	if (scb_s->ecd & ECD_MEF) {
  		scb_s->epdx += vcpu->kvm->arch.epdx;
  		if (scb_s->epoch < vcpu->kvm->arch.epoch)
  			scb_s->epdx += 1;
  	}
  
  	preempt_enable();
  }
  
  /*
   * Unregister a shadow scb from a VCPU.
   */
  static void unregister_shadow_scb(struct kvm_vcpu *vcpu)
  {
  	atomic_andnot(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
  	WRITE_ONCE(vcpu->arch.vsie_block, NULL);
  }
  
  /*
   * Run the vsie on a shadowed scb, managing the gmap shadow, handling
   * prefix pages and faults.
   *
   * Returns: - 0 if no errors occurred
   *          - > 0 if control has to be given to guest 2
   *          - -ENOMEM if out of memory
   */
  static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
  {
  	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
  	int rc = 0;
  
  	while (1) {
  		rc = acquire_gmap_shadow(vcpu, vsie_page);
  		if (!rc)
  			rc = map_prefix(vcpu, vsie_page);
  		if (!rc) {
  			gmap_enable(vsie_page->gmap);
  			update_intervention_requests(vsie_page);
  			rc = do_vsie_run(vcpu, vsie_page);
  			gmap_enable(vcpu->arch.gmap);
  		}
  		atomic_andnot(PROG_BLOCK_SIE, &scb_s->prog20);
  
  		if (rc == -EAGAIN)
  			rc = 0;
  		if (rc || scb_s->icptcode || signal_pending(current) ||
  		    kvm_s390_vcpu_has_irq(vcpu, 0))
  			break;
  	}
  
  	if (rc == -EFAULT) {
  		/*
  		 * Addressing exceptions are always presentes as intercepts.
  		 * As addressing exceptions are suppressing and our guest 3 PSW
  		 * points at the responsible instruction, we have to
  		 * forward the PSW and set the ilc. If we can't read guest 3
  		 * instruction, we can use an arbitrary ilc. Let's always use
  		 * ilen = 4 for now, so we can avoid reading in guest 3 virtual
  		 * memory. (we could also fake the shadow so the hardware
  		 * handles it).
  		 */
  		scb_s->icptcode = ICPT_PROGI;
  		scb_s->iprcc = PGM_ADDRESSING;
  		scb_s->pgmilc = 4;
  		scb_s->gpsw.addr = __rewind_psw(scb_s->gpsw, 4);
  	}
  	return rc;
  }
  
  /*
   * Get or create a vsie page for a scb address.
   *
   * Returns: - address of a vsie page (cached or new one)
   *          - NULL if the same scb address is already used by another VCPU
   *          - ERR_PTR(-ENOMEM) if out of memory
   */
  static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
  {
  	struct vsie_page *vsie_page;
  	struct page *page;
  	int nr_vcpus;
  
  	rcu_read_lock();
  	page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9);
  	rcu_read_unlock();
  	if (page) {
  		if (page_ref_inc_return(page) == 2)
  			return page_to_virt(page);
  		page_ref_dec(page);
  	}
  
  	/*
  	 * We want at least #online_vcpus shadows, so every VCPU can execute
  	 * the VSIE in parallel.
  	 */
  	nr_vcpus = atomic_read(&kvm->online_vcpus);
  
  	mutex_lock(&kvm->arch.vsie.mutex);
  	if (kvm->arch.vsie.page_count < nr_vcpus) {
  		page = alloc_page(GFP_KERNEL | __GFP_ZERO | GFP_DMA);
  		if (!page) {
  			mutex_unlock(&kvm->arch.vsie.mutex);
  			return ERR_PTR(-ENOMEM);
  		}
  		page_ref_inc(page);
  		kvm->arch.vsie.pages[kvm->arch.vsie.page_count] = page;
  		kvm->arch.vsie.page_count++;
  	} else {
  		/* reuse an existing entry that belongs to nobody */
  		while (true) {
  			page = kvm->arch.vsie.pages[kvm->arch.vsie.next];
  			if (page_ref_inc_return(page) == 2)
  				break;
  			page_ref_dec(page);
  			kvm->arch.vsie.next++;
  			kvm->arch.vsie.next %= nr_vcpus;
  		}
  		radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9);
  	}
  	page->index = addr;
  	/* double use of the same address */
  	if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) {
  		page_ref_dec(page);
  		mutex_unlock(&kvm->arch.vsie.mutex);
  		return NULL;
  	}
  	mutex_unlock(&kvm->arch.vsie.mutex);
  
  	vsie_page = page_to_virt(page);
  	memset(&vsie_page->scb_s, 0, sizeof(struct kvm_s390_sie_block));
  	release_gmap_shadow(vsie_page);
  	vsie_page->fault_addr = 0;
  	vsie_page->scb_s.ihcpu = 0xffffU;
  	return vsie_page;
  }
  
  /* put a vsie page acquired via get_vsie_page */
  static void put_vsie_page(struct kvm *kvm, struct vsie_page *vsie_page)
  {
  	struct page *page = pfn_to_page(__pa(vsie_page) >> PAGE_SHIFT);
  
  	page_ref_dec(page);
  }
  
  int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
  {
  	struct vsie_page *vsie_page;
  	unsigned long scb_addr;
  	int rc;
  
  	vcpu->stat.instruction_sie++;
  	if (!test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_SIEF2))
  		return -EOPNOTSUPP;
  	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
  		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
  
  	BUILD_BUG_ON(sizeof(struct vsie_page) != PAGE_SIZE);
  	scb_addr = kvm_s390_get_base_disp_s(vcpu, NULL);
  
  	/* 512 byte alignment */
  	if (unlikely(scb_addr & 0x1ffUL))
  		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
  
  	if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0))
  		return 0;
  
  	vsie_page = get_vsie_page(vcpu->kvm, scb_addr);
  	if (IS_ERR(vsie_page))
  		return PTR_ERR(vsie_page);
  	else if (!vsie_page)
  		/* double use of sie control block - simply do nothing */
  		return 0;
  
  	rc = pin_scb(vcpu, vsie_page, scb_addr);
  	if (rc)
  		goto out_put;
  	rc = shadow_scb(vcpu, vsie_page);
  	if (rc)
  		goto out_unpin_scb;
  	rc = pin_blocks(vcpu, vsie_page);
  	if (rc)
  		goto out_unshadow;
  	register_shadow_scb(vcpu, vsie_page);
  	rc = vsie_run(vcpu, vsie_page);
  	unregister_shadow_scb(vcpu);
  	unpin_blocks(vcpu, vsie_page);
  out_unshadow:
  	unshadow_scb(vcpu, vsie_page);
  out_unpin_scb:
  	unpin_scb(vcpu, vsie_page, scb_addr);
  out_put:
  	put_vsie_page(vcpu->kvm, vsie_page);
  
  	return rc < 0 ? rc : 0;
  }
  
  /* Init the vsie data structures. To be called when a vm is initialized. */
  void kvm_s390_vsie_init(struct kvm *kvm)
  {
  	mutex_init(&kvm->arch.vsie.mutex);
  	INIT_RADIX_TREE(&kvm->arch.vsie.addr_to_page, GFP_KERNEL);
  }
  
  /* Destroy the vsie data structures. To be called when a vm is destroyed. */
  void kvm_s390_vsie_destroy(struct kvm *kvm)
  {
  	struct vsie_page *vsie_page;
  	struct page *page;
  	int i;
  
  	mutex_lock(&kvm->arch.vsie.mutex);
  	for (i = 0; i < kvm->arch.vsie.page_count; i++) {
  		page = kvm->arch.vsie.pages[i];
  		kvm->arch.vsie.pages[i] = NULL;
  		vsie_page = page_to_virt(page);
  		release_gmap_shadow(vsie_page);
  		/* free the radix tree entry */
  		radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9);
  		__free_page(page);
  	}
  	kvm->arch.vsie.page_count = 0;
  	mutex_unlock(&kvm->arch.vsie.mutex);
  }
  
  void kvm_s390_vsie_kick(struct kvm_vcpu *vcpu)
  {
  	struct kvm_s390_sie_block *scb = READ_ONCE(vcpu->arch.vsie_block);
  
  	/*
  	 * Even if the VCPU lets go of the shadow sie block reference, it is
  	 * still valid in the cache. So we can safely kick it.
  	 */
  	if (scb) {
  		atomic_or(PROG_BLOCK_SIE, &scb->prog20);
  		if (scb->prog0c & PROG_IN_SIE)
  			atomic_or(CPUSTAT_STOP_INT, &scb->cpuflags);
  	}
  }
  