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[S390] kvm: fix address mode switching

598841ca9919d008b520114d8a4378c4ce4e40a1 ([S390] use gmap address spaces for kvm guest images) changed kvm to use a separate address space for kvm guests. This address space was switched in __vcpu_run In some cases (preemption, page fault) there is the possibility that this address space switch is lost. The typical symptom was a huge amount of validity intercepts or random guest addressing exceptions. Fix this by doing the switch in sie_loop and sie_exit and saving the address space in the gmap structure itself. Also use the preempt notifier.

Christian Borntraeger committed 15 years ago

Commit 480e5921 parent 9d037a75 files · +15 −10Browse files

Unified · Split

5 files
  1. arch/s390/include/asm/pgtable.h +2 −0
  2. arch/s390/kernel/asm-offsets.c +3 −0
  3. arch/s390/kernel/entry64.S +6 −0
  4. arch/s390/kvm/kvm-s390.c +2 −2
  5. arch/s390/mm/pgtable.c +2 −8
arch/s390/include/asm/pgtable.h+2−0
@@ -658,12 +658,14 @@ static inline void pgste_set_pte(pte_t *ptep, pgste_t pgste) · 657 unmodified lines
658658 * struct gmap_struct - guest address space
659659 * @mm: pointer to the parent mm_struct
660660 * @table: pointer to the page directory
661+ * @asce: address space control element for gmap page table
661662 * @crst_list: list of all crst tables used in the guest address space
662663 */
663664 struct gmap {
664665 struct list_head list;
665666 struct mm_struct *mm;
666667 unsigned long *table;
668+ unsigned long asce;
667669 struct list_head crst_list;
668670 };
669671
arch/s390/kernel/asm-offsets.c+3−0
@@ -10,6 +10,7 @@ · 9 unmodified lines
1010 #include <linux/sched.h>
1111 #include <asm/vdso.h>
1212 #include <asm/sigp.h>
13+#include <asm/pgtable.h>
1314
1415 /*
1516 * Make sure that the compiler is new enough. We want a compiler that
@@ -126,6 +127,7 @@ int main(void) · 110 unmodified lines
126127 DEFINE(__LC_KERNEL_STACK, offsetof(struct _lowcore, kernel_stack));
127128 DEFINE(__LC_ASYNC_STACK, offsetof(struct _lowcore, async_stack));
128129 DEFINE(__LC_PANIC_STACK, offsetof(struct _lowcore, panic_stack));
130+ DEFINE(__LC_USER_ASCE, offsetof(struct _lowcore, user_asce));
129131 DEFINE(__LC_INT_CLOCK, offsetof(struct _lowcore, int_clock));
130132 DEFINE(__LC_MCCK_CLOCK, offsetof(struct _lowcore, mcck_clock));
131133 DEFINE(__LC_MACHINE_FLAGS, offsetof(struct _lowcore, machine_flags));
@@ -151,6 +153,7 @@ int main(void) · 19 unmodified lines
151153 DEFINE(__LC_VDSO_PER_CPU, offsetof(struct _lowcore, vdso_per_cpu_data));
152154 DEFINE(__LC_GMAP, offsetof(struct _lowcore, gmap));
153155 DEFINE(__LC_CMF_HPP, offsetof(struct _lowcore, cmf_hpp));
156+ DEFINE(__GMAP_ASCE, offsetof(struct gmap, asce));
154157 #endif /* CONFIG_32BIT */
155158 return 0;
156159 }
arch/s390/kernel/entry64.S+6−0
@@ -1076,6 +1076,11 @@ sie_loop: · 1075 unmodified lines
10761076 lg %r14,__LC_THREAD_INFO # pointer thread_info struct
10771077 tm __TI_flags+7(%r14),_TIF_EXIT_SIE
10781078 jnz sie_exit
1079+ lg %r14,__LC_GMAP # get gmap pointer
1080+ ltgr %r14,%r14
1081+ jz sie_gmap
1082+ lctlg %c1,%c1,__GMAP_ASCE(%r14) # load primary asce
1083+sie_gmap:
10791084 lg %r14,__SF_EMPTY(%r15) # get control block pointer
10801085 SPP __SF_EMPTY(%r15) # set guest id
10811086 sie 0(%r14)
@@ -1083,6 +1088,7 @@ sie_done: · 1 unmodified line
10831088 SPP __LC_CMF_HPP # set host id
10841089 lg %r14,__LC_THREAD_INFO # pointer thread_info struct
10851090 sie_exit:
1091+ lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
10861092 ni __TI_flags+6(%r14),255-(_TIF_SIE>>8)
10871093 lg %r14,__SF_EMPTY+8(%r15) # load guest register save area
10881094 stmg %r0,%r13,0(%r14) # save guest gprs 0-13
arch/s390/kvm/kvm-s390.c+2−2
@@ -263,10 +263,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) · 262 unmodified lines
263263 vcpu->arch.guest_fpregs.fpc &= FPC_VALID_MASK;
264264 restore_fp_regs(&vcpu->arch.guest_fpregs);
265265 restore_access_regs(vcpu->arch.guest_acrs);
266+ gmap_enable(vcpu->arch.gmap);
266267 }
267268
268269 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
269270 {
271+ gmap_disable(vcpu->arch.gmap);
270272 save_fp_regs(&vcpu->arch.guest_fpregs);
271273 save_access_regs(vcpu->arch.guest_acrs);
272274 restore_fp_regs(&vcpu->arch.host_fpregs);
@@ -461,7 +463,6 @@ static void __vcpu_run(struct kvm_vcpu *vcpu) · 188 unmodified lines
461463 local_irq_disable();
462464 kvm_guest_enter();
463465 local_irq_enable();
464− gmap_enable(vcpu->arch.gmap);
465466 VCPU_EVENT(vcpu, 6, "entering sie flags %x",
466467 atomic_read(&vcpu->arch.sie_block->cpuflags));
467468 if (sie64a(vcpu->arch.sie_block, vcpu->arch.guest_gprs)) {
@@ -470,7 +471,6 @@ static void __vcpu_run(struct kvm_vcpu *vcpu) · 2 unmodified lines
470471 }
471472 VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
472473 vcpu->arch.sie_block->icptcode);
473− gmap_disable(vcpu->arch.gmap);
474474 local_irq_disable();
475475 kvm_guest_exit();
476476 local_irq_enable();
arch/s390/mm/pgtable.c+2−8
@@ -160,6 +160,8 @@ struct gmap *gmap_alloc(struct mm_struct *mm) · 159 unmodified lines
160160 table = (unsigned long *) page_to_phys(page);
161161 crst_table_init(table, _REGION1_ENTRY_EMPTY);
162162 gmap->table = table;
163+ gmap->asce = _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH |
164+ _ASCE_USER_BITS | __pa(table);
163165 list_add(&gmap->list, &mm->context.gmap_list);
164166 return gmap;
165167
@@ -240,10 +242,6 @@ EXPORT_SYMBOL_GPL(gmap_free); · 74 unmodified lines
240242 */
241243 void gmap_enable(struct gmap *gmap)
242244 {
243− /* Load primary space page table origin. */
244− S390_lowcore.user_asce = _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH |
245− _ASCE_USER_BITS | __pa(gmap->table);
246− asm volatile("lctlg 1,1,%0\n" : : "m" (S390_lowcore.user_asce) );
247245 S390_lowcore.gmap = (unsigned long) gmap;
248246 }
249247 EXPORT_SYMBOL_GPL(gmap_enable);
@@ -254,10 +252,6 @@ EXPORT_SYMBOL_GPL(gmap_enable); · 4 unmodified lines
254252 */
255253 void gmap_disable(struct gmap *gmap)
256254 {
257− /* Load primary space page table origin. */
258− S390_lowcore.user_asce =
259− gmap->mm->context.asce_bits | __pa(gmap->mm->pgd);
260− asm volatile("lctlg 1,1,%0\n" : : "m" (S390_lowcore.user_asce) );
261255 S390_lowcore.gmap = 0UL;
262256 }
263257 EXPORT_SYMBOL_GPL(gmap_disable);