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[S390] kvm guest address space mapping

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Add code that allows KVM to control the virtual memory layout that
is seen by a guest. The guest address space uses a second page table
that shares the last level pte-tables with the process page table.
If a page is unmapped from the process page table it is automatically
unmapped from the guest page table as well.

The guest address space mapping starts out empty, KVM can map any
individual 1MB segments from the process virtual memory to any 1MB
aligned location in the guest virtual memory. If a target segment in
the process virtual memory does not exist or is unmapped while a
guest mapping exists the desired target address is stored as an
invalid segment table entry in the guest page table.
The population of the guest page table is fault driven.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2011-07-24 10:48:20 +02:00
parent 144d634a21
commit e5992f2e6c
11 changed files with 489 additions and 52 deletions
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18
arch/s390/mm/fault.c
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@@ -303,9 +303,24 @@ static inline int do_exception(struct pt_regs *regs, int access,
flags = FAULT_FLAG_ALLOW_RETRY;
if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
flags |= FAULT_FLAG_WRITE;
retry:
down_read(&mm->mmap_sem);
#ifdef CONFIG_PGSTE
if (test_tsk_thread_flag(current, TIF_SIE) && S390_lowcore.gmap) {
address = gmap_fault(address,
(struct gmap *) S390_lowcore.gmap);
if (address == -EFAULT) {
fault = VM_FAULT_BADMAP;
goto out_up;
}
if (address == -ENOMEM) {
fault = VM_FAULT_OOM;
goto out_up;
}
}
#endif
retry:
fault = VM_FAULT_BADMAP;
vma = find_vma(mm, address);
if (!vma)
@@ -356,6 +371,7 @@ retry:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
down_read(&mm->mmap_sem);
goto retry;
}
}