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authorRusty Russell <rusty@rustcorp.com.au>2010-04-14 23:43:54 -0400
committerRusty Russell <rusty@rustcorp.com.au>2010-04-14 08:13:56 -0400
commit091ebf07a2408f9a56634caa0f86d9360e9af23b (patch)
tree62d3b3424cc1c0dc71b3b750bb1e8e063e658fd3
parent5094aeafbbd500509f648e3cd102b053bc7926b3 (diff)
lguest: stop using KVM hypercall mechanism
This is a partial revert of 4cd8b5e2a159 "lguest: use KVM hypercalls"; we revert to using (just as questionable but more reliable) int $15 for hypercalls. I didn't revert the register mapping, so we still use the same calling convention as kvm. KVM in more recent incarnations stopped injecting a fault when a guest tried to use the VMCALL instruction from ring 1, so lguest under kvm fails to make hypercalls. It was nice to share code with our KVM cousins, but this was overreach. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Matias Zabaljauregui <zabaljauregui@gmail.com> Cc: Avi Kivity <avi@redhat.com>
-rw-r--r--arch/x86/include/asm/lguest_hcall.h29
-rw-r--r--arch/x86/lguest/boot.c61
-rw-r--r--arch/x86/lguest/i386_head.S2
-rw-r--r--drivers/lguest/lguest_device.c4
4 files changed, 56 insertions, 40 deletions
diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h
index ba0eed8aa1a6..b60f2924c413 100644
--- a/arch/x86/include/asm/lguest_hcall.h
+++ b/arch/x86/include/asm/lguest_hcall.h
@@ -28,22 +28,39 @@
28 28
29#ifndef __ASSEMBLY__ 29#ifndef __ASSEMBLY__
30#include <asm/hw_irq.h> 30#include <asm/hw_irq.h>
31#include <asm/kvm_para.h>
32 31
33/*G:030 32/*G:030
34 * But first, how does our Guest contact the Host to ask for privileged 33 * But first, how does our Guest contact the Host to ask for privileged
35 * operations? There are two ways: the direct way is to make a "hypercall", 34 * operations? There are two ways: the direct way is to make a "hypercall",
36 * to make requests of the Host Itself. 35 * to make requests of the Host Itself.
37 * 36 *
38 * We use the KVM hypercall mechanism, though completely different hypercall 37 * Our hypercall mechanism uses the highest unused trap code (traps 32 and
39 * numbers. Seventeen hypercalls are available: the hypercall number is put in 38 * above are used by real hardware interrupts). Seventeen hypercalls are
40 * the %eax register, and the arguments (when required) are placed in %ebx, 39 * available: the hypercall number is put in the %eax register, and the
41 * %ecx, %edx and %esi. If a return value makes sense, it's returned in %eax. 40 * arguments (when required) are placed in %ebx, %ecx, %edx and %esi.
41 * If a return value makes sense, it's returned in %eax.
42 * 42 *
43 * Grossly invalid calls result in Sudden Death at the hands of the vengeful 43 * Grossly invalid calls result in Sudden Death at the hands of the vengeful
44 * Host, rather than returning failure. This reflects Winston Churchill's 44 * Host, rather than returning failure. This reflects Winston Churchill's
45 * definition of a gentleman: "someone who is only rude intentionally". 45 * definition of a gentleman: "someone who is only rude intentionally".
46:*/ 46 */
47static inline unsigned long
48hcall(unsigned long call,
49 unsigned long arg1, unsigned long arg2, unsigned long arg3,
50 unsigned long arg4)
51{
52 /* "int" is the Intel instruction to trigger a trap. */
53 asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
54 /* The call in %eax (aka "a") might be overwritten */
55 : "=a"(call)
56 /* The arguments are in %eax, %ebx, %ecx, %edx & %esi */
57 : "a"(call), "b"(arg1), "c"(arg2), "d"(arg3), "S"(arg4)
58 /* "memory" means this might write somewhere in memory.
59 * This isn't true for all calls, but it's safe to tell
60 * gcc that it might happen so it doesn't get clever. */
61 : "memory");
62 return call;
63}
47 64
48/* Can't use our min() macro here: needs to be a constant */ 65/* Can't use our min() macro here: needs to be a constant */
49#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32) 66#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 7e59dc1d3fc2..2bdf628066bd 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -115,7 +115,7 @@ static void async_hcall(unsigned long call, unsigned long arg1,
115 local_irq_save(flags); 115 local_irq_save(flags);
116 if (lguest_data.hcall_status[next_call] != 0xFF) { 116 if (lguest_data.hcall_status[next_call] != 0xFF) {
117 /* Table full, so do normal hcall which will flush table. */ 117 /* Table full, so do normal hcall which will flush table. */
118 kvm_hypercall4(call, arg1, arg2, arg3, arg4); 118 hcall(call, arg1, arg2, arg3, arg4);
119 } else { 119 } else {
120 lguest_data.hcalls[next_call].arg0 = call; 120 lguest_data.hcalls[next_call].arg0 = call;
121 lguest_data.hcalls[next_call].arg1 = arg1; 121 lguest_data.hcalls[next_call].arg1 = arg1;
@@ -145,46 +145,45 @@ static void async_hcall(unsigned long call, unsigned long arg1,
145 * So, when we're in lazy mode, we call async_hcall() to store the call for 145 * So, when we're in lazy mode, we call async_hcall() to store the call for
146 * future processing: 146 * future processing:
147 */ 147 */
148static void lazy_hcall1(unsigned long call, 148static void lazy_hcall1(unsigned long call, unsigned long arg1)
149 unsigned long arg1)
150{ 149{
151 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) 150 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
152 kvm_hypercall1(call, arg1); 151 hcall(call, arg1, 0, 0, 0);
153 else 152 else
154 async_hcall(call, arg1, 0, 0, 0); 153 async_hcall(call, arg1, 0, 0, 0);
155} 154}
156 155
157/* You can imagine what lazy_hcall2, 3 and 4 look like. :*/ 156/* You can imagine what lazy_hcall2, 3 and 4 look like. :*/
158static void lazy_hcall2(unsigned long call, 157static void lazy_hcall2(unsigned long call,
159 unsigned long arg1, 158 unsigned long arg1,
160 unsigned long arg2) 159 unsigned long arg2)
161{ 160{
162 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) 161 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
163 kvm_hypercall2(call, arg1, arg2); 162 hcall(call, arg1, arg2, 0, 0);
164 else 163 else
165 async_hcall(call, arg1, arg2, 0, 0); 164 async_hcall(call, arg1, arg2, 0, 0);
166} 165}
167 166
168static void lazy_hcall3(unsigned long call, 167static void lazy_hcall3(unsigned long call,
169 unsigned long arg1, 168 unsigned long arg1,
170 unsigned long arg2, 169 unsigned long arg2,
171 unsigned long arg3) 170 unsigned long arg3)
172{ 171{
173 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) 172 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
174 kvm_hypercall3(call, arg1, arg2, arg3); 173 hcall(call, arg1, arg2, arg3, 0);
175 else 174 else
176 async_hcall(call, arg1, arg2, arg3, 0); 175 async_hcall(call, arg1, arg2, arg3, 0);
177} 176}
178 177
179#ifdef CONFIG_X86_PAE 178#ifdef CONFIG_X86_PAE
180static void lazy_hcall4(unsigned long call, 179static void lazy_hcall4(unsigned long call,
181 unsigned long arg1, 180 unsigned long arg1,
182 unsigned long arg2, 181 unsigned long arg2,
183 unsigned long arg3, 182 unsigned long arg3,
184 unsigned long arg4) 183 unsigned long arg4)
185{ 184{
186 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) 185 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
187 kvm_hypercall4(call, arg1, arg2, arg3, arg4); 186 hcall(call, arg1, arg2, arg3, arg4);
188 else 187 else
189 async_hcall(call, arg1, arg2, arg3, arg4); 188 async_hcall(call, arg1, arg2, arg3, arg4);
190} 189}
@@ -196,13 +195,13 @@ static void lazy_hcall4(unsigned long call,
196:*/ 195:*/
197static void lguest_leave_lazy_mmu_mode(void) 196static void lguest_leave_lazy_mmu_mode(void)
198{ 197{
199 kvm_hypercall0(LHCALL_FLUSH_ASYNC); 198 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
200 paravirt_leave_lazy_mmu(); 199 paravirt_leave_lazy_mmu();
201} 200}
202 201
203static void lguest_end_context_switch(struct task_struct *next) 202static void lguest_end_context_switch(struct task_struct *next)
204{ 203{
205 kvm_hypercall0(LHCALL_FLUSH_ASYNC); 204 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
206 paravirt_end_context_switch(next); 205 paravirt_end_context_switch(next);
207} 206}
208 207
@@ -286,7 +285,7 @@ static void lguest_write_idt_entry(gate_desc *dt,
286 /* Keep the local copy up to date. */ 285 /* Keep the local copy up to date. */
287 native_write_idt_entry(dt, entrynum, g); 286 native_write_idt_entry(dt, entrynum, g);
288 /* Tell Host about this new entry. */ 287 /* Tell Host about this new entry. */
289 kvm_hypercall3(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]); 288 hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1], 0);
290} 289}
291 290
292/* 291/*
@@ -300,7 +299,7 @@ static void lguest_load_idt(const struct desc_ptr *desc)
300 struct desc_struct *idt = (void *)desc->address; 299 struct desc_struct *idt = (void *)desc->address;
301 300
302 for (i = 0; i < (desc->size+1)/8; i++) 301 for (i = 0; i < (desc->size+1)/8; i++)
303 kvm_hypercall3(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b); 302 hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b, 0);
304} 303}
305 304
306/* 305/*
@@ -321,7 +320,7 @@ static void lguest_load_gdt(const struct desc_ptr *desc)
321 struct desc_struct *gdt = (void *)desc->address; 320 struct desc_struct *gdt = (void *)desc->address;
322 321
323 for (i = 0; i < (desc->size+1)/8; i++) 322 for (i = 0; i < (desc->size+1)/8; i++)
324 kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, i, gdt[i].a, gdt[i].b); 323 hcall(LHCALL_LOAD_GDT_ENTRY, i, gdt[i].a, gdt[i].b, 0);
325} 324}
326 325
327/* 326/*
@@ -334,8 +333,8 @@ static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
334{ 333{
335 native_write_gdt_entry(dt, entrynum, desc, type); 334 native_write_gdt_entry(dt, entrynum, desc, type);
336 /* Tell Host about this new entry. */ 335 /* Tell Host about this new entry. */
337 kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, entrynum, 336 hcall(LHCALL_LOAD_GDT_ENTRY, entrynum,
338 dt[entrynum].a, dt[entrynum].b); 337 dt[entrynum].a, dt[entrynum].b, 0);
339} 338}
340 339
341/* 340/*
@@ -931,7 +930,7 @@ static int lguest_clockevent_set_next_event(unsigned long delta,
931 } 930 }
932 931
933 /* Please wake us this far in the future. */ 932 /* Please wake us this far in the future. */
934 kvm_hypercall1(LHCALL_SET_CLOCKEVENT, delta); 933 hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0, 0);
935 return 0; 934 return 0;
936} 935}
937 936
@@ -942,7 +941,7 @@ static void lguest_clockevent_set_mode(enum clock_event_mode mode,
942 case CLOCK_EVT_MODE_UNUSED: 941 case CLOCK_EVT_MODE_UNUSED:
943 case CLOCK_EVT_MODE_SHUTDOWN: 942 case CLOCK_EVT_MODE_SHUTDOWN:
944 /* A 0 argument shuts the clock down. */ 943 /* A 0 argument shuts the clock down. */
945 kvm_hypercall0(LHCALL_SET_CLOCKEVENT); 944 hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0, 0);
946 break; 945 break;
947 case CLOCK_EVT_MODE_ONESHOT: 946 case CLOCK_EVT_MODE_ONESHOT:
948 /* This is what we expect. */ 947 /* This is what we expect. */
@@ -1100,7 +1099,7 @@ static void set_lguest_basic_apic_ops(void)
1100/* STOP! Until an interrupt comes in. */ 1099/* STOP! Until an interrupt comes in. */
1101static void lguest_safe_halt(void) 1100static void lguest_safe_halt(void)
1102{ 1101{
1103 kvm_hypercall0(LHCALL_HALT); 1102 hcall(LHCALL_HALT, 0, 0, 0, 0);
1104} 1103}
1105 1104
1106/* 1105/*
@@ -1112,8 +1111,8 @@ static void lguest_safe_halt(void)
1112 */ 1111 */
1113static void lguest_power_off(void) 1112static void lguest_power_off(void)
1114{ 1113{
1115 kvm_hypercall2(LHCALL_SHUTDOWN, __pa("Power down"), 1114 hcall(LHCALL_SHUTDOWN, __pa("Power down"),
1116 LGUEST_SHUTDOWN_POWEROFF); 1115 LGUEST_SHUTDOWN_POWEROFF, 0, 0);
1117} 1116}
1118 1117
1119/* 1118/*
@@ -1123,7 +1122,7 @@ static void lguest_power_off(void)
1123 */ 1122 */
1124static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p) 1123static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
1125{ 1124{
1126 kvm_hypercall2(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF); 1125 hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0, 0);
1127 /* The hcall won't return, but to keep gcc happy, we're "done". */ 1126 /* The hcall won't return, but to keep gcc happy, we're "done". */
1128 return NOTIFY_DONE; 1127 return NOTIFY_DONE;
1129} 1128}
@@ -1162,7 +1161,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count)
1162 len = sizeof(scratch) - 1; 1161 len = sizeof(scratch) - 1;
1163 scratch[len] = '\0'; 1162 scratch[len] = '\0';
1164 memcpy(scratch, buf, len); 1163 memcpy(scratch, buf, len);
1165 kvm_hypercall1(LHCALL_NOTIFY, __pa(scratch)); 1164 hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0, 0);
1166 1165
1167 /* This routine returns the number of bytes actually written. */ 1166 /* This routine returns the number of bytes actually written. */
1168 return len; 1167 return len;
@@ -1174,7 +1173,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count)
1174 */ 1173 */
1175static void lguest_restart(char *reason) 1174static void lguest_restart(char *reason)
1176{ 1175{
1177 kvm_hypercall2(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART); 1176 hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0, 0);
1178} 1177}
1179 1178
1180/*G:050 1179/*G:050
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S
index 27eac0faee48..4f420c2f2d55 100644
--- a/arch/x86/lguest/i386_head.S
+++ b/arch/x86/lguest/i386_head.S
@@ -32,7 +32,7 @@ ENTRY(lguest_entry)
32 */ 32 */
33 movl $LHCALL_LGUEST_INIT, %eax 33 movl $LHCALL_LGUEST_INIT, %eax
34 movl $lguest_data - __PAGE_OFFSET, %ebx 34 movl $lguest_data - __PAGE_OFFSET, %ebx
35 .byte 0x0f,0x01,0xc1 /* KVM_HYPERCALL */ 35 int $LGUEST_TRAP_ENTRY
36 36
37 /* Set up the initial stack so we can run C code. */ 37 /* Set up the initial stack so we can run C code. */
38 movl $(init_thread_union+THREAD_SIZE),%esp 38 movl $(init_thread_union+THREAD_SIZE),%esp
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 07090f379c63..69c84a1d88ea 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -178,7 +178,7 @@ static void set_status(struct virtio_device *vdev, u8 status)
178 178
179 /* We set the status. */ 179 /* We set the status. */
180 to_lgdev(vdev)->desc->status = status; 180 to_lgdev(vdev)->desc->status = status;
181 kvm_hypercall1(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset); 181 hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
182} 182}
183 183
184static void lg_set_status(struct virtio_device *vdev, u8 status) 184static void lg_set_status(struct virtio_device *vdev, u8 status)
@@ -229,7 +229,7 @@ static void lg_notify(struct virtqueue *vq)
229 */ 229 */
230 struct lguest_vq_info *lvq = vq->priv; 230 struct lguest_vq_info *lvq = vq->priv;
231 231
232 kvm_hypercall1(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT); 232 hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0);
233} 233}
234 234
235/* An extern declaration inside a C file is bad form. Don't do it. */ 235/* An extern declaration inside a C file is bad form. Don't do it. */