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-rw-r--r--arch/powerpc/mm/mmu_context_hash64.c195
1 files changed, 1 insertions, 194 deletions
diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c
index ca988a3d5fb2..40677aa0190e 100644
--- a/arch/powerpc/mm/mmu_context_hash64.c
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -24,200 +24,7 @@
24 24
25#include <asm/mmu_context.h> 25#include <asm/mmu_context.h>
26 26
27#ifdef CONFIG_PPC_ICSWX 27#include "icswx.h"
28/*
29 * The processor and its L2 cache cause the icswx instruction to
30 * generate a COP_REQ transaction on PowerBus. The transaction has
31 * no address, and the processor does not perform an MMU access
32 * to authenticate the transaction. The command portion of the
33 * PowerBus COP_REQ transaction includes the LPAR_ID (LPID) and
34 * the coprocessor Process ID (PID), which the coprocessor compares
35 * to the authorized LPID and PID held in the coprocessor, to determine
36 * if the process is authorized to generate the transaction.
37 * The data of the COP_REQ transaction is 128-byte or less and is
38 * placed in cacheable memory on a 128-byte cache line boundary.
39 *
40 * The task to use a coprocessor should use use_cop() to allocate
41 * a coprocessor PID before executing icswx instruction. use_cop()
42 * also enables the coprocessor context switching. Drop_cop() is
43 * used to free the coprocessor PID.
44 *
45 * Example:
46 * Host Fabric Interface (HFI) is a PowerPC network coprocessor.
47 * Each HFI have multiple windows. Each HFI window serves as a
48 * network device sending to and receiving from HFI network.
49 * HFI immediate send function uses icswx instruction. The immediate
50 * send function allows small (single cache-line) packets be sent
51 * without using the regular HFI send FIFO and doorbell, which are
52 * much slower than immediate send.
53 *
54 * For each task intending to use HFI immediate send, the HFI driver
55 * calls use_cop() to obtain a coprocessor PID for the task.
56 * The HFI driver then allocate a free HFI window and save the
57 * coprocessor PID to the HFI window to allow the task to use the
58 * HFI window.
59 *
60 * The HFI driver repeatedly creates immediate send packets and
61 * issues icswx instruction to send data through the HFI window.
62 * The HFI compares the coprocessor PID in the CPU PID register
63 * to the PID held in the HFI window to determine if the transaction
64 * is allowed.
65 *
66 * When the task to release the HFI window, the HFI driver calls
67 * drop_cop() to release the coprocessor PID.
68 */
69
70#define COP_PID_NONE 0
71#define COP_PID_MIN (COP_PID_NONE + 1)
72#define COP_PID_MAX (0xFFFF)
73
74static DEFINE_SPINLOCK(mmu_context_acop_lock);
75static DEFINE_IDA(cop_ida);
76
77void switch_cop(struct mm_struct *next)
78{
79 mtspr(SPRN_PID, next->context.cop_pid);
80 mtspr(SPRN_ACOP, next->context.acop);
81}
82
83static int new_cop_pid(struct ida *ida, int min_id, int max_id,
84 spinlock_t *lock)
85{
86 int index;
87 int err;
88
89again:
90 if (!ida_pre_get(ida, GFP_KERNEL))
91 return -ENOMEM;
92
93 spin_lock(lock);
94 err = ida_get_new_above(ida, min_id, &index);
95 spin_unlock(lock);
96
97 if (err == -EAGAIN)
98 goto again;
99 else if (err)
100 return err;
101
102 if (index > max_id) {
103 spin_lock(lock);
104 ida_remove(ida, index);
105 spin_unlock(lock);
106 return -ENOMEM;
107 }
108
109 return index;
110}
111
112static void sync_cop(void *arg)
113{
114 struct mm_struct *mm = arg;
115
116 if (mm == current->active_mm)
117 switch_cop(current->active_mm);
118}
119
120/**
121 * Start using a coprocessor.
122 * @acop: mask of coprocessor to be used.
123 * @mm: The mm the coprocessor to associate with. Most likely current mm.
124 *
125 * Return a positive PID if successful. Negative errno otherwise.
126 * The returned PID will be fed to the coprocessor to determine if an
127 * icswx transaction is authenticated.
128 */
129int use_cop(unsigned long acop, struct mm_struct *mm)
130{
131 int ret;
132
133 if (!cpu_has_feature(CPU_FTR_ICSWX))
134 return -ENODEV;
135
136 if (!mm || !acop)
137 return -EINVAL;
138
139 /* The page_table_lock ensures mm_users won't change under us */
140 spin_lock(&mm->page_table_lock);
141 spin_lock(mm->context.cop_lockp);
142
143 if (mm->context.cop_pid == COP_PID_NONE) {
144 ret = new_cop_pid(&cop_ida, COP_PID_MIN, COP_PID_MAX,
145 &mmu_context_acop_lock);
146 if (ret < 0)
147 goto out;
148
149 mm->context.cop_pid = ret;
150 }
151 mm->context.acop |= acop;
152
153 sync_cop(mm);
154
155 /*
156 * If this is a threaded process then there might be other threads
157 * running. We need to send an IPI to force them to pick up any
158 * change in PID and ACOP.
159 */
160 if (atomic_read(&mm->mm_users) > 1)
161 smp_call_function(sync_cop, mm, 1);
162
163 ret = mm->context.cop_pid;
164
165out:
166 spin_unlock(mm->context.cop_lockp);
167 spin_unlock(&mm->page_table_lock);
168
169 return ret;
170}
171EXPORT_SYMBOL_GPL(use_cop);
172
173/**
174 * Stop using a coprocessor.
175 * @acop: mask of coprocessor to be stopped.
176 * @mm: The mm the coprocessor associated with.
177 */
178void drop_cop(unsigned long acop, struct mm_struct *mm)
179{
180 int free_pid = COP_PID_NONE;
181
182 if (!cpu_has_feature(CPU_FTR_ICSWX))
183 return;
184
185 if (WARN_ON_ONCE(!mm))
186 return;
187
188 /* The page_table_lock ensures mm_users won't change under us */
189 spin_lock(&mm->page_table_lock);
190 spin_lock(mm->context.cop_lockp);
191
192 mm->context.acop &= ~acop;
193
194 if ((!mm->context.acop) && (mm->context.cop_pid != COP_PID_NONE)) {
195 free_pid = mm->context.cop_pid;
196 mm->context.cop_pid = COP_PID_NONE;
197 }
198
199 sync_cop(mm);
200
201 /*
202 * If this is a threaded process then there might be other threads
203 * running. We need to send an IPI to force them to pick up any
204 * change in PID and ACOP.
205 */
206 if (atomic_read(&mm->mm_users) > 1)
207 smp_call_function(sync_cop, mm, 1);
208
209 if (free_pid != COP_PID_NONE) {
210 spin_lock(&mmu_context_acop_lock);
211 ida_remove(&cop_ida, free_pid);
212 spin_unlock(&mmu_context_acop_lock);
213 }
214
215 spin_unlock(mm->context.cop_lockp);
216 spin_unlock(&mm->page_table_lock);
217}
218EXPORT_SYMBOL_GPL(drop_cop);
219
220#endif /* CONFIG_PPC_ICSWX */
221 28
222static DEFINE_SPINLOCK(mmu_context_lock); 29static DEFINE_SPINLOCK(mmu_context_lock);
223static DEFINE_IDA(mmu_context_ida); 30static DEFINE_IDA(mmu_context_ida);
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