xref: /openbmc/linux/arch/powerpc/kvm/book3s_rtas.c (revision 0d727e18)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2012 Michael Ellerman, IBM Corporation.
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/kvm_host.h>
8 #include <linux/kvm.h>
9 #include <linux/err.h>
10 
11 #include <linux/uaccess.h>
12 #include <asm/kvm_book3s.h>
13 #include <asm/kvm_ppc.h>
14 #include <asm/hvcall.h>
15 #include <asm/rtas.h>
16 #include <asm/xive.h>
17 
18 #ifdef CONFIG_KVM_XICS
19 static void kvm_rtas_set_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
20 {
21 	u32 irq, server, priority;
22 	int rc;
23 
24 	if (be32_to_cpu(args->nargs) != 3 || be32_to_cpu(args->nret) != 1) {
25 		rc = -3;
26 		goto out;
27 	}
28 
29 	irq = be32_to_cpu(args->args[0]);
30 	server = be32_to_cpu(args->args[1]);
31 	priority = be32_to_cpu(args->args[2]);
32 
33 	if (xics_on_xive())
34 		rc = kvmppc_xive_set_xive(vcpu->kvm, irq, server, priority);
35 	else
36 		rc = kvmppc_xics_set_xive(vcpu->kvm, irq, server, priority);
37 	if (rc)
38 		rc = -3;
39 out:
40 	args->rets[0] = cpu_to_be32(rc);
41 }
42 
43 static void kvm_rtas_get_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
44 {
45 	u32 irq, server, priority;
46 	int rc;
47 
48 	if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 3) {
49 		rc = -3;
50 		goto out;
51 	}
52 
53 	irq = be32_to_cpu(args->args[0]);
54 
55 	server = priority = 0;
56 	if (xics_on_xive())
57 		rc = kvmppc_xive_get_xive(vcpu->kvm, irq, &server, &priority);
58 	else
59 		rc = kvmppc_xics_get_xive(vcpu->kvm, irq, &server, &priority);
60 	if (rc) {
61 		rc = -3;
62 		goto out;
63 	}
64 
65 	args->rets[1] = cpu_to_be32(server);
66 	args->rets[2] = cpu_to_be32(priority);
67 out:
68 	args->rets[0] = cpu_to_be32(rc);
69 }
70 
71 static void kvm_rtas_int_off(struct kvm_vcpu *vcpu, struct rtas_args *args)
72 {
73 	u32 irq;
74 	int rc;
75 
76 	if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 1) {
77 		rc = -3;
78 		goto out;
79 	}
80 
81 	irq = be32_to_cpu(args->args[0]);
82 
83 	if (xics_on_xive())
84 		rc = kvmppc_xive_int_off(vcpu->kvm, irq);
85 	else
86 		rc = kvmppc_xics_int_off(vcpu->kvm, irq);
87 	if (rc)
88 		rc = -3;
89 out:
90 	args->rets[0] = cpu_to_be32(rc);
91 }
92 
93 static void kvm_rtas_int_on(struct kvm_vcpu *vcpu, struct rtas_args *args)
94 {
95 	u32 irq;
96 	int rc;
97 
98 	if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 1) {
99 		rc = -3;
100 		goto out;
101 	}
102 
103 	irq = be32_to_cpu(args->args[0]);
104 
105 	if (xics_on_xive())
106 		rc = kvmppc_xive_int_on(vcpu->kvm, irq);
107 	else
108 		rc = kvmppc_xics_int_on(vcpu->kvm, irq);
109 	if (rc)
110 		rc = -3;
111 out:
112 	args->rets[0] = cpu_to_be32(rc);
113 }
114 #endif /* CONFIG_KVM_XICS */
115 
116 struct rtas_handler {
117 	void (*handler)(struct kvm_vcpu *vcpu, struct rtas_args *args);
118 	char *name;
119 };
120 
121 static struct rtas_handler rtas_handlers[] = {
122 #ifdef CONFIG_KVM_XICS
123 	{ .name = "ibm,set-xive", .handler = kvm_rtas_set_xive },
124 	{ .name = "ibm,get-xive", .handler = kvm_rtas_get_xive },
125 	{ .name = "ibm,int-off",  .handler = kvm_rtas_int_off },
126 	{ .name = "ibm,int-on",   .handler = kvm_rtas_int_on },
127 #endif
128 };
129 
130 struct rtas_token_definition {
131 	struct list_head list;
132 	struct rtas_handler *handler;
133 	u64 token;
134 };
135 
136 static int rtas_name_matches(char *s1, char *s2)
137 {
138 	struct kvm_rtas_token_args args;
139 	return !strncmp(s1, s2, sizeof(args.name));
140 }
141 
142 static int rtas_token_undefine(struct kvm *kvm, char *name)
143 {
144 	struct rtas_token_definition *d, *tmp;
145 
146 	lockdep_assert_held(&kvm->arch.rtas_token_lock);
147 
148 	list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
149 		if (rtas_name_matches(d->handler->name, name)) {
150 			list_del(&d->list);
151 			kfree(d);
152 			return 0;
153 		}
154 	}
155 
156 	/* It's not an error to undefine an undefined token */
157 	return 0;
158 }
159 
160 static int rtas_token_define(struct kvm *kvm, char *name, u64 token)
161 {
162 	struct rtas_token_definition *d;
163 	struct rtas_handler *h = NULL;
164 	bool found;
165 	int i;
166 
167 	lockdep_assert_held(&kvm->arch.rtas_token_lock);
168 
169 	list_for_each_entry(d, &kvm->arch.rtas_tokens, list) {
170 		if (d->token == token)
171 			return -EEXIST;
172 	}
173 
174 	found = false;
175 	for (i = 0; i < ARRAY_SIZE(rtas_handlers); i++) {
176 		h = &rtas_handlers[i];
177 		if (rtas_name_matches(h->name, name)) {
178 			found = true;
179 			break;
180 		}
181 	}
182 
183 	if (!found)
184 		return -ENOENT;
185 
186 	d = kzalloc(sizeof(*d), GFP_KERNEL);
187 	if (!d)
188 		return -ENOMEM;
189 
190 	d->handler = h;
191 	d->token = token;
192 
193 	list_add_tail(&d->list, &kvm->arch.rtas_tokens);
194 
195 	return 0;
196 }
197 
198 int kvm_vm_ioctl_rtas_define_token(struct kvm *kvm, void __user *argp)
199 {
200 	struct kvm_rtas_token_args args;
201 	int rc;
202 
203 	if (copy_from_user(&args, argp, sizeof(args)))
204 		return -EFAULT;
205 
206 	mutex_lock(&kvm->arch.rtas_token_lock);
207 
208 	if (args.token)
209 		rc = rtas_token_define(kvm, args.name, args.token);
210 	else
211 		rc = rtas_token_undefine(kvm, args.name);
212 
213 	mutex_unlock(&kvm->arch.rtas_token_lock);
214 
215 	return rc;
216 }
217 
218 int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
219 {
220 	struct rtas_token_definition *d;
221 	struct rtas_args args;
222 	rtas_arg_t *orig_rets;
223 	gpa_t args_phys;
224 	int rc;
225 
226 	/*
227 	 * r4 contains the guest physical address of the RTAS args
228 	 * Mask off the top 4 bits since this is a guest real address
229 	 */
230 	args_phys = kvmppc_get_gpr(vcpu, 4) & KVM_PAM;
231 
232 	kvm_vcpu_srcu_read_lock(vcpu);
233 	rc = kvm_read_guest(vcpu->kvm, args_phys, &args, sizeof(args));
234 	kvm_vcpu_srcu_read_unlock(vcpu);
235 	if (rc)
236 		goto fail;
237 
238 	/*
239 	 * args->rets is a pointer into args->args. Now that we've
240 	 * copied args we need to fix it up to point into our copy,
241 	 * not the guest args. We also need to save the original
242 	 * value so we can restore it on the way out.
243 	 */
244 	orig_rets = args.rets;
245 	if (be32_to_cpu(args.nargs) >= ARRAY_SIZE(args.args)) {
246 		/*
247 		 * Don't overflow our args array: ensure there is room for
248 		 * at least rets[0] (even if the call specifies 0 nret).
249 		 *
250 		 * Each handler must then check for the correct nargs and nret
251 		 * values, but they may always return failure in rets[0].
252 		 */
253 		rc = -EINVAL;
254 		goto fail;
255 	}
256 	args.rets = &args.args[be32_to_cpu(args.nargs)];
257 
258 	mutex_lock(&vcpu->kvm->arch.rtas_token_lock);
259 
260 	rc = -ENOENT;
261 	list_for_each_entry(d, &vcpu->kvm->arch.rtas_tokens, list) {
262 		if (d->token == be32_to_cpu(args.token)) {
263 			d->handler->handler(vcpu, &args);
264 			rc = 0;
265 			break;
266 		}
267 	}
268 
269 	mutex_unlock(&vcpu->kvm->arch.rtas_token_lock);
270 
271 	if (rc == 0) {
272 		args.rets = orig_rets;
273 		rc = kvm_write_guest(vcpu->kvm, args_phys, &args, sizeof(args));
274 		if (rc)
275 			goto fail;
276 	}
277 
278 	return rc;
279 
280 fail:
281 	/*
282 	 * We only get here if the guest has called RTAS with a bogus
283 	 * args pointer or nargs/nret values that would overflow the
284 	 * array. That means we can't get to the args, and so we can't
285 	 * fail the RTAS call. So fail right out to userspace, which
286 	 * should kill the guest.
287 	 *
288 	 * SLOF should actually pass the hcall return value from the
289 	 * rtas handler call in r3, so enter_rtas could be modified to
290 	 * return a failure indication in r3 and we could return such
291 	 * errors to the guest rather than failing to host userspace.
292 	 * However old guests that don't test for failure could then
293 	 * continue silently after errors, so for now we won't do this.
294 	 */
295 	return rc;
296 }
297 EXPORT_SYMBOL_GPL(kvmppc_rtas_hcall);
298 
299 void kvmppc_rtas_tokens_free(struct kvm *kvm)
300 {
301 	struct rtas_token_definition *d, *tmp;
302 
303 	list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
304 		list_del(&d->list);
305 		kfree(d);
306 	}
307 }
308