1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __KVM_X86_MMU_INTERNAL_H
3#define __KVM_X86_MMU_INTERNAL_H
4
5#include <linux/types.h>
6#include <linux/kvm_host.h>
7#include <asm/kvm_host.h>
8
9#ifdef CONFIG_KVM_PROVE_MMU
10#define KVM_MMU_WARN_ON(x) WARN_ON_ONCE(x)
11#else
12#define KVM_MMU_WARN_ON(x) BUILD_BUG_ON_INVALID(x)
13#endif
14
15/* Page table builder macros common to shadow (host) PTEs and guest PTEs. */
16#define __PT_LEVEL_SHIFT(level, bits_per_level)	\
17	(PAGE_SHIFT + ((level) - 1) * (bits_per_level))
18#define __PT_INDEX(address, level, bits_per_level) \
19	(((address) >> __PT_LEVEL_SHIFT(level, bits_per_level)) & ((1 << (bits_per_level)) - 1))
20
21#define __PT_LVL_ADDR_MASK(base_addr_mask, level, bits_per_level) \
22	((base_addr_mask) & ~((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1))
23
24#define __PT_LVL_OFFSET_MASK(base_addr_mask, level, bits_per_level) \
25	((base_addr_mask) & ((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1))
26
27#define __PT_ENT_PER_PAGE(bits_per_level)  (1 << (bits_per_level))
28
29/*
30 * Unlike regular MMU roots, PAE "roots", a.k.a. PDPTEs/PDPTRs, have a PRESENT
31 * bit, and thus are guaranteed to be non-zero when valid.  And, when a guest
32 * PDPTR is !PRESENT, its corresponding PAE root cannot be set to INVALID_PAGE,
33 * as the CPU would treat that as PRESENT PDPTR with reserved bits set.  Use
34 * '0' instead of INVALID_PAGE to indicate an invalid PAE root.
35 */
36#define INVALID_PAE_ROOT	0
37#define IS_VALID_PAE_ROOT(x)	(!!(x))
38
39static inline hpa_t kvm_mmu_get_dummy_root(void)
40{
41	return my_zero_pfn(0) << PAGE_SHIFT;
42}
43
44static inline bool kvm_mmu_is_dummy_root(hpa_t shadow_page)
45{
46	return is_zero_pfn(shadow_page >> PAGE_SHIFT);
47}
48
49typedef u64 __rcu *tdp_ptep_t;
50
51struct kvm_mmu_page {
52	/*
53	 * Note, "link" through "spt" fit in a single 64 byte cache line on
54	 * 64-bit kernels, keep it that way unless there's a reason not to.
55	 */
56	struct list_head link;
57	struct hlist_node hash_link;
58
59	bool tdp_mmu_page;
60	bool unsync;
61	union {
62		u8 mmu_valid_gen;
63
64		/* Only accessed under slots_lock.  */
65		bool tdp_mmu_scheduled_root_to_zap;
66	};
67
68	 /*
69	  * The shadow page can't be replaced by an equivalent huge page
70	  * because it is being used to map an executable page in the guest
71	  * and the NX huge page mitigation is enabled.
72	  */
73	bool nx_huge_page_disallowed;
74
75	/*
76	 * The following two entries are used to key the shadow page in the
77	 * hash table.
78	 */
79	union kvm_mmu_page_role role;
80	gfn_t gfn;
81
82	u64 *spt;
83
84	/*
85	 * Stores the result of the guest translation being shadowed by each
86	 * SPTE.  KVM shadows two types of guest translations: nGPA -> GPA
87	 * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both
88	 * cases the result of the translation is a GPA and a set of access
89	 * constraints.
90	 *
91	 * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed
92	 * access permissions are stored in the lower bits. Note, for
93	 * convenience and uniformity across guests, the access permissions are
94	 * stored in KVM format (e.g.  ACC_EXEC_MASK) not the raw guest format.
95	 */
96	u64 *shadowed_translation;
97
98	/* Currently serving as active root */
99	union {
100		int root_count;
101		refcount_t tdp_mmu_root_count;
102	};
103	unsigned int unsync_children;
104	union {
105		struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
106		tdp_ptep_t ptep;
107	};
108	DECLARE_BITMAP(unsync_child_bitmap, 512);
109
110	/*
111	 * Tracks shadow pages that, if zapped, would allow KVM to create an NX
112	 * huge page.  A shadow page will have nx_huge_page_disallowed set but
113	 * not be on the list if a huge page is disallowed for other reasons,
114	 * e.g. because KVM is shadowing a PTE at the same gfn, the memslot
115	 * isn't properly aligned, etc...
116	 */
117	struct list_head possible_nx_huge_page_link;
118#ifdef CONFIG_X86_32
119	/*
120	 * Used out of the mmu-lock to avoid reading spte values while an
121	 * update is in progress; see the comments in __get_spte_lockless().
122	 */
123	int clear_spte_count;
124#endif
125
126	/* Number of writes since the last time traversal visited this page.  */
127	atomic_t write_flooding_count;
128
129#ifdef CONFIG_X86_64
130	/* Used for freeing the page asynchronously if it is a TDP MMU page. */
131	struct rcu_head rcu_head;
132#endif
133};
134
135extern struct kmem_cache *mmu_page_header_cache;
136
137static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role)
138{
139	return role.smm ? 1 : 0;
140}
141
142static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
143{
144	return kvm_mmu_role_as_id(sp->role);
145}
146
147static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp)
148{
149	/*
150	 * When using the EPT page-modification log, the GPAs in the CPU dirty
151	 * log would come from L2 rather than L1.  Therefore, we need to rely
152	 * on write protection to record dirty pages, which bypasses PML, since
153	 * writes now result in a vmexit.  Note, the check on CPU dirty logging
154	 * being enabled is mandatory as the bits used to denote WP-only SPTEs
155	 * are reserved for PAE paging (32-bit KVM).
156	 */
157	return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode;
158}
159
160static inline gfn_t gfn_round_for_level(gfn_t gfn, int level)
161{
162	return gfn & -KVM_PAGES_PER_HPAGE(level);
163}
164
165int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot,
166			    gfn_t gfn, bool can_unsync, bool prefetch);
167
168void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
169void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
170bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
171				    struct kvm_memory_slot *slot, u64 gfn,
172				    int min_level);
173
174/* Flush the given page (huge or not) of guest memory. */
175static inline void kvm_flush_remote_tlbs_gfn(struct kvm *kvm, gfn_t gfn, int level)
176{
177	kvm_flush_remote_tlbs_range(kvm, gfn_round_for_level(gfn, level),
178				    KVM_PAGES_PER_HPAGE(level));
179}
180
181unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
182
183extern int nx_huge_pages;
184static inline bool is_nx_huge_page_enabled(struct kvm *kvm)
185{
186	return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages;
187}
188
189struct kvm_page_fault {
190	/* arguments to kvm_mmu_do_page_fault.  */
191	const gpa_t addr;
192	const u32 error_code;
193	const bool prefetch;
194
195	/* Derived from error_code.  */
196	const bool exec;
197	const bool write;
198	const bool present;
199	const bool rsvd;
200	const bool user;
201
202	/* Derived from mmu and global state.  */
203	const bool is_tdp;
204	const bool nx_huge_page_workaround_enabled;
205
206	/*
207	 * Whether a >4KB mapping can be created or is forbidden due to NX
208	 * hugepages.
209	 */
210	bool huge_page_disallowed;
211
212	/*
213	 * Maximum page size that can be created for this fault; input to
214	 * FNAME(fetch), direct_map() and kvm_tdp_mmu_map().
215	 */
216	u8 max_level;
217
218	/*
219	 * Page size that can be created based on the max_level and the
220	 * page size used by the host mapping.
221	 */
222	u8 req_level;
223
224	/*
225	 * Page size that will be created based on the req_level and
226	 * huge_page_disallowed.
227	 */
228	u8 goal_level;
229
230	/* Shifted addr, or result of guest page table walk if addr is a gva.  */
231	gfn_t gfn;
232
233	/* The memslot containing gfn. May be NULL. */
234	struct kvm_memory_slot *slot;
235
236	/* Outputs of kvm_faultin_pfn.  */
237	unsigned long mmu_seq;
238	kvm_pfn_t pfn;
239	hva_t hva;
240	bool map_writable;
241
242	/*
243	 * Indicates the guest is trying to write a gfn that contains one or
244	 * more of the PTEs used to translate the write itself, i.e. the access
245	 * is changing its own translation in the guest page tables.
246	 */
247	bool write_fault_to_shadow_pgtable;
248};
249
250int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
251
252/*
253 * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(),
254 * and of course kvm_mmu_do_page_fault().
255 *
256 * RET_PF_CONTINUE: So far, so good, keep handling the page fault.
257 * RET_PF_RETRY: let CPU fault again on the address.
258 * RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
259 * RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
260 * RET_PF_FIXED: The faulting entry has been fixed.
261 * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU.
262 *
263 * Any names added to this enum should be exported to userspace for use in
264 * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h
265 *
266 * Note, all values must be greater than or equal to zero so as not to encroach
267 * on -errno return values.  Somewhat arbitrarily use '0' for CONTINUE, which
268 * will allow for efficient machine code when checking for CONTINUE, e.g.
269 * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero.
270 */
271enum {
272	RET_PF_CONTINUE = 0,
273	RET_PF_RETRY,
274	RET_PF_EMULATE,
275	RET_PF_INVALID,
276	RET_PF_FIXED,
277	RET_PF_SPURIOUS,
278};
279
280static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
281					u32 err, bool prefetch, int *emulation_type)
282{
283	struct kvm_page_fault fault = {
284		.addr = cr2_or_gpa,
285		.error_code = err,
286		.exec = err & PFERR_FETCH_MASK,
287		.write = err & PFERR_WRITE_MASK,
288		.present = err & PFERR_PRESENT_MASK,
289		.rsvd = err & PFERR_RSVD_MASK,
290		.user = err & PFERR_USER_MASK,
291		.prefetch = prefetch,
292		.is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
293		.nx_huge_page_workaround_enabled =
294			is_nx_huge_page_enabled(vcpu->kvm),
295
296		.max_level = KVM_MAX_HUGEPAGE_LEVEL,
297		.req_level = PG_LEVEL_4K,
298		.goal_level = PG_LEVEL_4K,
299	};
300	int r;
301
302	if (vcpu->arch.mmu->root_role.direct) {
303		fault.gfn = fault.addr >> PAGE_SHIFT;
304		fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn);
305	}
306
307	/*
308	 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the
309	 * guest perspective and have already been counted at the time of the
310	 * original fault.
311	 */
312	if (!prefetch)
313		vcpu->stat.pf_taken++;
314
315	if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp)
316		r = kvm_tdp_page_fault(vcpu, &fault);
317	else
318		r = vcpu->arch.mmu->page_fault(vcpu, &fault);
319
320	if (fault.write_fault_to_shadow_pgtable && emulation_type)
321		*emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
322
323	/*
324	 * Similar to above, prefetch faults aren't truly spurious, and the
325	 * async #PF path doesn't do emulation.  Do count faults that are fixed
326	 * by the async #PF handler though, otherwise they'll never be counted.
327	 */
328	if (r == RET_PF_FIXED)
329		vcpu->stat.pf_fixed++;
330	else if (prefetch)
331		;
332	else if (r == RET_PF_EMULATE)
333		vcpu->stat.pf_emulate++;
334	else if (r == RET_PF_SPURIOUS)
335		vcpu->stat.pf_spurious++;
336	return r;
337}
338
339int kvm_mmu_max_mapping_level(struct kvm *kvm,
340			      const struct kvm_memory_slot *slot, gfn_t gfn,
341			      int max_level);
342void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
343void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level);
344
345void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
346
347void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp);
348void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp);
349
350#endif /* __KVM_X86_MMU_INTERNAL_H */
351