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Vancouver: map solely requested memory region

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Don't map all memory of the VM at once, instead only the one permitted
by the memory model. Otherwise memory regions get mapped which must not,
where each instruction and memory access have to cause an exception in
order to emulate it step by step.
This commit is contained in:
Alexander Boettcher 2012-09-10 14:22:47 +02:00 committed by Norman Feske
parent 315a8437e3
commit f5efbff19c
1 changed files with 81 additions and 19 deletions
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100
ports/src/vancouver/main.cc
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@ -337,43 +337,105 @@ class Vcpu_dispatcher : public Genode::Thread<STACK_SIZE>,
msg.cpu->mtd = msg.mtr_out; msg.cpu->mtd = msg.mtr_out;
} }
/**
* Get position of the least significant 1 bit.
* bsf is undefined for value == 0.
*/
Genode::addr_t bsf(Genode::addr_t value) {
return __builtin_ctz(value); }
bool max_map_crd(Nova::Mem_crd &crd, Genode::addr_t vmm_start,
Genode::addr_t vm_start, Genode::addr_t size,
Genode::addr_t vm_fault)
{
Nova::Mem_crd crd_save = crd;
retry:
/* lookup whether page is mapped and its size */
Nova::uint8_t ret = Nova::lookup(crd);
if (ret != Nova::NOVA_OK)
return false;
/* page is not mapped, touch it */
if (crd.is_null()) {
crd = crd_save;
Genode::touch_read((unsigned char volatile *)crd.addr());
goto retry;
}
/* cut-set crd region and vmm region */
Genode::addr_t cut_start = Genode::max(vmm_start, crd.base());
Genode::addr_t cut_size = Genode::min(vmm_start + size,
crd.base() + (1UL << crd.order())) -
cut_start;
/* calculate minimal order of page to be mapped */
Genode::addr_t map_page = vmm_start + vm_fault - vm_start;
Genode::addr_t map_order = bsf(vm_fault | map_page | cut_size);
Genode::addr_t hotspot = 0;
/* calculate maximal aligned order of page to be mapped */
do {
crd = Nova::Mem_crd(map_page, map_order,
Nova::Rights(true, true, true));
map_order += 1;
map_page &= ~((1UL << map_order) - 1);
hotspot = vm_start + map_page - vmm_start;
}
while (cut_start <= map_page &&
((map_page + (1UL << map_order)) <= (cut_start + cut_size)) &&
!(hotspot & ((1UL << map_order) - 1)));
return true;
}
bool _handle_map_memory(bool need_unmap) bool _handle_map_memory(bool need_unmap)
{ {
Utcb *utcb = _utcb_of_myself(); Utcb *utcb = _utcb_of_myself();
Genode::addr_t const fault_addr = utcb->qual[1]; Genode::addr_t const vm_fault_addr = utcb->qual[1];
MessageMemRegion mem_region(fault_addr >> 12);
if (verbose_npt) if (verbose_npt)
Logging::printf("--> request mapping at 0x%lx\n", fault_addr); Logging::printf("--> request mapping at 0x%lx\n", vm_fault_addr);
if (!_motherboard.bus_memregion.send(mem_region, true) || !mem_region.ptr) MessageMemRegion mem_region(vm_fault_addr >> PAGE_SIZE_LOG2);
if (!_motherboard.bus_memregion.send(mem_region, true) ||
!mem_region.ptr)
return false; return false;
if (verbose_npt) if (verbose_npt)
Logging::printf("MemRegion: page=%lx, start_page=%lx, count=%lx, ptr=%p\n", Logging::printf("VM page 0x%lx in [0x%lx:0x%lx),"
mem_region.page, mem_region.start_page, mem_region.count, mem_region.ptr); " VMM area: [0x%lx:0x%lx)\n",
mem_region.page, mem_region.start_page,
mem_region.start_page + mem_region.count,
(Genode::addr_t)mem_region.ptr >> PAGE_SIZE_LOG2,
((Genode::addr_t)mem_region.ptr >> PAGE_SIZE_LOG2)
+ mem_region.count);
Genode::addr_t src = (Genode::addr_t)_guest_memory.backing_store_local_base() + Genode::addr_t vmm_memory_base =
(mem_region.page << PAGE_SIZE_LOG2); reinterpret_cast<Genode::addr_t>(mem_region.ptr);
Genode::touch_read((unsigned char volatile *)src); Genode::addr_t vmm_memory_fault = vmm_memory_base +
(vm_fault_addr - (mem_region.start_page << PAGE_SIZE_LOG2));
Nova::Mem_crd crd(src >> PAGE_SIZE_LOG2, 32 - PAGE_SIZE_LOG2, Nova::Mem_crd crd(vmm_memory_fault >> PAGE_SIZE_LOG2, 0,
Nova::Rights(true, true, true)); Nova::Rights(true, true, true));
Nova::uint8_t ret = Nova::lookup(crd); if (!max_map_crd(crd, vmm_memory_base >> PAGE_SIZE_LOG2,
mem_region.start_page,
if (verbose_npt) mem_region.count, mem_region.page))
Logging::printf("looked up crd (base=0x%lx, order=%ld)\n", Logging::panic("mapping failed");
crd.base(), crd.order());
if (need_unmap) if (need_unmap)
Logging::panic("_handle_map_memory: need_unmap not handled, yet\n"); Logging::panic("_handle_map_memory: need_unmap not handled, yet\n");
Nova::mword_t hotspot = mem_region.page << 12; Genode::addr_t hotspot = (mem_region.start_page << PAGE_SIZE_LOG2)
+ crd.addr() - vmm_memory_base;
if (verbose_npt) if (verbose_npt)
Logging::printf("NPT mapping (base=0x%lx, order=%d hotspot=0x%lx)\n", Logging::printf("NPT mapping (base=0x%lx, order=%d, hotspot=0x%lx)\n",
crd.base(), crd.order(), hotspot); crd.base(), crd.order(), hotspot);
/* EPT violation during IDT vectoring? */ /* EPT violation during IDT vectoring? */
@ -412,7 +474,7 @@ class Vcpu_dispatcher : public Genode::Thread<STACK_SIZE>,
void _svm_npt() void _svm_npt()
{ {
Utcb *utcb = _utcb_of_myself(); Utcb *utcb = _utcb_of_myself();
MessageMemRegion msg(utcb->qual[1] >> 12); MessageMemRegion msg(utcb->qual[1] >> PAGE_SIZE_LOG2);
if (!_handle_map_memory(utcb->qual[0] & 1)) if (!_handle_map_memory(utcb->qual[0] & 1))
_svm_invalid(); _svm_invalid();
} }