diag.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * handling diagnose instructions
  4 *
  5 * Copyright IBM Corp. 2008, 2020
  6 *
  7 *    Author(s): Carsten Otte <cotte@de.ibm.com>
  8 *               Christian Borntraeger <borntraeger@de.ibm.com>
  9 */
 10
 11#include <linux/kvm.h>
 12#include <linux/kvm_host.h>
 13#include <asm/gmap.h>
 14#include <asm/gmap_helpers.h>
 15#include <asm/virtio-ccw.h>
 16#include "kvm-s390.h"
 17#include "trace.h"
 18#include "trace-s390.h"
 19#include "gaccess.h"
 20
 21static void do_discard_gfn_range(struct kvm_vcpu *vcpu, gfn_t gfn_start, gfn_t gfn_end)
 22{
 23	struct kvm_memslot_iter iter;
 24	struct kvm_memory_slot *slot;
 25	struct kvm_memslots *slots;
 26	unsigned long start, end;
 27
 28	slots = kvm_vcpu_memslots(vcpu);
 29
 30	kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) {
 31		slot = iter.slot;
 32		start = __gfn_to_hva_memslot(slot, max(gfn_start, slot->base_gfn));
 33		end = __gfn_to_hva_memslot(slot, min(gfn_end, slot->base_gfn + slot->npages));
 34		gmap_helper_discard(vcpu->kvm->mm, start, end);
 35	}
 36}
 37
 38static int diag_release_pages(struct kvm_vcpu *vcpu)
 39{
 40	unsigned long start, end;
 41	unsigned long prefix  = kvm_s390_get_prefix(vcpu);
 42
 43	start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
 44	end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + PAGE_SIZE;
 45	vcpu->stat.instruction_diagnose_10++;
 46
 47	if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
 48	    || start < 2 * PAGE_SIZE)
 49		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 50
 51	VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
 52
 53	mmap_read_lock(vcpu->kvm->mm);
 54	/*
 55	 * We checked for start >= end above, so lets check for the
 56	 * fast path (no prefix swap page involved)
 57	 */
 58	if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
 59		do_discard_gfn_range(vcpu, gpa_to_gfn(start), gpa_to_gfn(end));
 60	} else {
 61		/*
 62		 * This is slow path.  gmap_discard will check for start
 63		 * so lets split this into before prefix, prefix, after
 64		 * prefix and let gmap_discard make some of these calls
 65		 * NOPs.
 66		 */
 67		do_discard_gfn_range(vcpu, gpa_to_gfn(start), gpa_to_gfn(prefix));
 68		if (start <= prefix)
 69			do_discard_gfn_range(vcpu, 0, 1);
 70		if (end > prefix + PAGE_SIZE)
 71			do_discard_gfn_range(vcpu, 1, 2);
 72		do_discard_gfn_range(vcpu, gpa_to_gfn(prefix) + 2, gpa_to_gfn(end));
 73	}
 74	mmap_read_unlock(vcpu->kvm->mm);
 75	return 0;
 76}
 77
 78static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
 79{
 80	struct prs_parm {
 81		u16 code;
 82		u16 subcode;
 83		u16 parm_len;
 84		u16 parm_version;
 85		u64 token_addr;
 86		u64 select_mask;
 87		u64 compare_mask;
 88		u64 zarch;
 89	};
 90	struct prs_parm parm;
 91	int rc;
 92	u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
 93	u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
 94
 95	VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
 96		   vcpu->run->s.regs.gprs[rx]);
 97	vcpu->stat.instruction_diagnose_258++;
 98	if (vcpu->run->s.regs.gprs[rx] & 7)
 99		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
100	rc = read_guest_real(vcpu, vcpu->run->s.regs.gprs[rx], &parm, sizeof(parm));
101	if (rc)
102		return kvm_s390_inject_prog_cond(vcpu, rc);
103	if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
104		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
105
106	switch (parm.subcode) {
107	case 0: /* TOKEN */
108		VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
109			   "select mask 0x%llx compare mask 0x%llx",
110			   parm.token_addr, parm.select_mask, parm.compare_mask);
111		if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
112			/*
113			 * If the pagefault handshake is already activated,
114			 * the token must not be changed.  We have to return
115			 * decimal 8 instead, as mandated in SC24-6084.
116			 */
117			vcpu->run->s.regs.gprs[ry] = 8;
118			return 0;
119		}
120
121		if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
122		    parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
123			return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
124
125		if (!kvm_is_gpa_in_memslot(vcpu->kvm, parm.token_addr))
126			return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
127
128		vcpu->arch.pfault_token = parm.token_addr;
129		vcpu->arch.pfault_select = parm.select_mask;
130		vcpu->arch.pfault_compare = parm.compare_mask;
131		vcpu->run->s.regs.gprs[ry] = 0;
132		rc = 0;
133		break;
134	case 1: /*
135		 * CANCEL
136		 * Specification allows to let already pending tokens survive
137		 * the cancel, therefore to reduce code complexity, we assume
138		 * all outstanding tokens are already pending.
139		 */
140		VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
141		if (parm.token_addr || parm.select_mask ||
142		    parm.compare_mask || parm.zarch)
143			return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
144
145		vcpu->run->s.regs.gprs[ry] = 0;
146		/*
147		 * If the pfault handling was not established or is already
148		 * canceled SC24-6084 requests to return decimal 4.
149		 */
150		if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
151			vcpu->run->s.regs.gprs[ry] = 4;
152		else
153			vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
154
155		rc = 0;
156		break;
157	default:
158		rc = -EOPNOTSUPP;
159		break;
160	}
161
162	return rc;
163}
164
165static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
166{
167	VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
168	vcpu->stat.instruction_diagnose_44++;
169	kvm_vcpu_on_spin(vcpu, true);
170	return 0;
171}
172
173static int forward_cnt;
174static unsigned long cur_slice;
175
176static int diag9c_forwarding_overrun(void)
177{
178	/* Reset the count on a new slice */
179	if (time_after(jiffies, cur_slice)) {
180		cur_slice = jiffies;
181		forward_cnt = diag9c_forwarding_hz / HZ;
182	}
183	return forward_cnt-- <= 0 ? 1 : 0;
184}
185
186static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
187{
188	struct kvm_vcpu *tcpu;
189	int tcpu_cpu;
190	int tid;
191
192	tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
193	vcpu->stat.instruction_diagnose_9c++;
194
195	/* yield to self */
196	if (tid == vcpu->vcpu_id)
197		goto no_yield;
198
199	/* yield to invalid */
200	tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
201	if (!tcpu)
202		goto no_yield;
203
204	/* target guest VCPU already running */
205	tcpu_cpu = READ_ONCE(tcpu->cpu);
206	if (tcpu_cpu >= 0) {
207		if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
208			goto no_yield;
209
210		/* target host CPU already running */
211		if (!vcpu_is_preempted(tcpu_cpu))
212			goto no_yield;
213		smp_yield_cpu(tcpu_cpu);
214		VCPU_EVENT(vcpu, 5,
215			   "diag time slice end directed to %d: yield forwarded",
216			   tid);
217		vcpu->stat.diag_9c_forward++;
218		return 0;
219	}
220
221	if (kvm_vcpu_yield_to(tcpu) <= 0)
222		goto no_yield;
223
224	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
225	return 0;
226no_yield:
227	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
228	vcpu->stat.diag_9c_ignored++;
229	return 0;
230}
231
232static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
233{
234	unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
235	unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
236
237	VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
238	vcpu->stat.instruction_diagnose_308++;
239	switch (subcode) {
240	case 3:
241		vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
242		break;
243	case 4:
244		vcpu->run->s390_reset_flags = 0;
245		break;
246	default:
247		return -EOPNOTSUPP;
248	}
249
250	/*
251	 * no need to check the return value of vcpu_stop as it can only have
252	 * an error for protvirt, but protvirt means user cpu state
253	 */
254	if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
255		kvm_s390_vcpu_stop(vcpu);
256	vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
257	vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
258	vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
259	vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
260	VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
261	  vcpu->run->s390_reset_flags);
262	trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
263	return -EREMOTE;
264}
265
266static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
267{
268	int ret;
269
270	vcpu->stat.instruction_diagnose_500++;
271	/* No virtio-ccw notification? Get out quickly. */
272	if (!vcpu->kvm->arch.css_support ||
273	    (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
274		return -EOPNOTSUPP;
275
276	VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
277			    (u32) vcpu->run->s.regs.gprs[2],
278			    (u32) vcpu->run->s.regs.gprs[3],
279			    vcpu->run->s.regs.gprs[4]);
280
281	/*
282	 * The layout is as follows:
283	 * - gpr 2 contains the subchannel id (passed as addr)
284	 * - gpr 3 contains the virtqueue index (passed as datamatch)
285	 * - gpr 4 contains the index on the bus (optionally)
286	 */
287	ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
288				      vcpu->run->s.regs.gprs[2] & 0xffffffff,
289				      8, &vcpu->run->s.regs.gprs[3],
290				      vcpu->run->s.regs.gprs[4]);
291
292	/*
293	 * Return cookie in gpr 2, but don't overwrite the register if the
294	 * diagnose will be handled by userspace.
295	 */
296	if (ret != -EOPNOTSUPP)
297		vcpu->run->s.regs.gprs[2] = ret;
298	/* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
299	return ret < 0 ? ret : 0;
300}
301
302int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
303{
304	int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
305
306	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
307		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
308
309	trace_kvm_s390_handle_diag(vcpu, code);
310	switch (code) {
311	case 0x10:
312		return diag_release_pages(vcpu);
313	case 0x44:
314		return __diag_time_slice_end(vcpu);
315	case 0x9c:
316		return __diag_time_slice_end_directed(vcpu);
317	case 0x258:
318		return __diag_page_ref_service(vcpu);
319	case 0x308:
320		return __diag_ipl_functions(vcpu);
321	case 0x500:
322		return __diag_virtio_hypercall(vcpu);
323	default:
324		vcpu->stat.instruction_diagnose_other++;
325		return -EOPNOTSUPP;
326	}
327}