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kvm: Support KVM_CLEAR_DIRTY_LOG 

Firstly detect the interface using KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
and mark it.  When failed to enable the new feature we'll fall back to
the old sync.

Provide the log_clear() hook for the memory listeners for both address
spaces of KVM (normal system memory, and SMM) and deliever the clear
message to kernel.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190603065056.25211-11-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Xu 2019-06-03 14:50:55 +08:00 committed by Juan Quintela
parent 36adac4934
commit ff4aa11419
2 changed files with 183 additions and 0 deletions
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182
accel/kvm/kvm-all.c
View File

@ -91,6 +91,7 @@ struct KVMState
int many_ioeventfds;
int intx_set_mask;
bool sync_mmu;
bool manual_dirty_log_protect;
/* The man page (and posix) say ioctl numbers are signed int, but
* they're not. Linux, glibc and *BSD all treat ioctl numbers as
* unsigned, and treating them as signed here can break things */
@ -560,6 +561,159 @@ out:
return ret;
}
/* Alignment requirement for KVM_CLEAR_DIRTY_LOG - 64 pages */
#define KVM_CLEAR_LOG_SHIFT 6
#define KVM_CLEAR_LOG_ALIGN (qemu_real_host_page_size << KVM_CLEAR_LOG_SHIFT)
#define KVM_CLEAR_LOG_MASK (-KVM_CLEAR_LOG_ALIGN)
/**
* kvm_physical_log_clear - Clear the kernel's dirty bitmap for range
*
* NOTE: this will be a no-op if we haven't enabled manual dirty log
* protection in the host kernel because in that case this operation
* will be done within log_sync().
*
* @kml: the kvm memory listener
* @section: the memory range to clear dirty bitmap
*/
static int kvm_physical_log_clear(KVMMemoryListener *kml,
MemoryRegionSection *section)
{
KVMState *s = kvm_state;
struct kvm_clear_dirty_log d;
uint64_t start, end, bmap_start, start_delta, bmap_npages, size;
unsigned long *bmap_clear = NULL, psize = qemu_real_host_page_size;
KVMSlot *mem = NULL;
int ret, i;
if (!s->manual_dirty_log_protect) {
/* No need to do explicit clear */
return 0;
}
start = section->offset_within_address_space;
size = int128_get64(section->size);
if (!size) {
/* Nothing more we can do... */
return 0;
}
kvm_slots_lock(kml);
/* Find any possible slot that covers the section */
for (i = 0; i < s->nr_slots; i++) {
mem = &kml->slots[i];
if (mem->start_addr <= start &&
start + size <= mem->start_addr + mem->memory_size) {
break;
}
}
/*
* We should always find one memslot until this point, otherwise
* there could be something wrong from the upper layer
*/
assert(mem && i != s->nr_slots);
/*
* We need to extend either the start or the size or both to
* satisfy the KVM interface requirement. Firstly, do the start
* page alignment on 64 host pages
*/
bmap_start = (start - mem->start_addr) & KVM_CLEAR_LOG_MASK;
start_delta = start - mem->start_addr - bmap_start;
bmap_start /= psize;
/*
* The kernel interface has restriction on the size too, that either:
*
* (1) the size is 64 host pages aligned (just like the start), or
* (2) the size fills up until the end of the KVM memslot.
*/
bmap_npages = DIV_ROUND_UP(size + start_delta, KVM_CLEAR_LOG_ALIGN)
<< KVM_CLEAR_LOG_SHIFT;
end = mem->memory_size / psize;
if (bmap_npages > end - bmap_start) {
bmap_npages = end - bmap_start;
}
start_delta /= psize;
/*
* Prepare the bitmap to clear dirty bits. Here we must guarantee
* that we won't clear any unknown dirty bits otherwise we might
* accidentally clear some set bits which are not yet synced from
* the kernel into QEMU's bitmap, then we'll lose track of the
* guest modifications upon those pages (which can directly lead
* to guest data loss or panic after migration).
*
* Layout of the KVMSlot.dirty_bmap:
*
* |<-------- bmap_npages -----------..>|
* [1]
* start_delta size
* |----------------|-------------|------------------|------------|
* ^ ^ ^ ^
* | | | |
* start bmap_start (start) end
* of memslot of memslot
*
* [1] bmap_npages can be aligned to either 64 pages or the end of slot
*/
assert(bmap_start % BITS_PER_LONG == 0);
/* We should never do log_clear before log_sync */
assert(mem->dirty_bmap);
if (start_delta) {
/* Slow path - we need to manipulate a temp bitmap */
bmap_clear = bitmap_new(bmap_npages);
bitmap_copy_with_src_offset(bmap_clear, mem->dirty_bmap,
bmap_start, start_delta + size / psize);
/*
* We need to fill the holes at start because that was not
* specified by the caller and we extended the bitmap only for
* 64 pages alignment
*/
bitmap_clear(bmap_clear, 0, start_delta);
d.dirty_bitmap = bmap_clear;
} else {
/* Fast path - start address aligns well with BITS_PER_LONG */
d.dirty_bitmap = mem->dirty_bmap + BIT_WORD(bmap_start);
}
d.first_page = bmap_start;
/* It should never overflow. If it happens, say something */
assert(bmap_npages <= UINT32_MAX);
d.num_pages = bmap_npages;
d.slot = mem->slot | (kml->as_id << 16);
if (kvm_vm_ioctl(s, KVM_CLEAR_DIRTY_LOG, &d) == -1) {
ret = -errno;
error_report("%s: KVM_CLEAR_DIRTY_LOG failed, slot=%d, "
"start=0x%"PRIx64", size=0x%"PRIx32", errno=%d",
__func__, d.slot, (uint64_t)d.first_page,
(uint32_t)d.num_pages, ret);
} else {
ret = 0;
trace_kvm_clear_dirty_log(d.slot, d.first_page, d.num_pages);
}
/*
* After we have updated the remote dirty bitmap, we update the
* cached bitmap as well for the memslot, then if another user
* clears the same region we know we shouldn't clear it again on
* the remote otherwise it's data loss as well.
*/
bitmap_clear(mem->dirty_bmap, bmap_start + start_delta,
size / psize);
/* This handles the NULL case well */
g_free(bmap_clear);
kvm_slots_unlock(kml);
return ret;
}
static void kvm_coalesce_mmio_region(MemoryListener *listener,
MemoryRegionSection *secion,
hwaddr start, hwaddr size)
@ -894,6 +1048,22 @@ static void kvm_log_sync(MemoryListener *listener,
}
}
static void kvm_log_clear(MemoryListener *listener,
MemoryRegionSection *section)
{
KVMMemoryListener *kml = container_of(listener, KVMMemoryListener, listener);
int r;
r = kvm_physical_log_clear(kml, section);
if (r < 0) {
error_report_once("%s: kvm log clear failed: mr=%s "
"offset=%"HWADDR_PRIx" size=%"PRIx64, __func__,
section->mr->name, section->offset_within_region,
int128_get64(section->size));
abort();
}
}
static void kvm_mem_ioeventfd_add(MemoryListener *listener,
MemoryRegionSection *section,
bool match_data, uint64_t data,
@ -985,6 +1155,7 @@ void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
kml->listener.log_start = kvm_log_start;
kml->listener.log_stop = kvm_log_stop;
kml->listener.log_sync = kvm_log_sync;
kml->listener.log_clear = kvm_log_clear;
kml->listener.priority = 10;
memory_listener_register(&kml->listener, as);
@ -1709,6 +1880,17 @@ static int kvm_init(MachineState *ms)
s->coalesced_pio = s->coalesced_mmio &&
kvm_check_extension(s, KVM_CAP_COALESCED_PIO);
s->manual_dirty_log_protect =
kvm_check_extension(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
if (s->manual_dirty_log_protect) {
ret = kvm_vm_enable_cap(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2, 0, 1);
if (ret) {
warn_report("Trying to enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 "
"but failed. Falling back to the legacy mode. ");
s->manual_dirty_log_protect = false;
}
}
#ifdef KVM_CAP_VCPU_EVENTS
s->vcpu_events = kvm_check_extension(s, KVM_CAP_VCPU_EVENTS);
#endif

1
accel/kvm/trace-events
View File

@ -15,4 +15,5 @@ kvm_irqchip_release_virq(int virq) "virq %d"
kvm_set_ioeventfd_mmio(int fd, uint64_t addr, uint32_t val, bool assign, uint32_t size, bool datamatch) "fd: %d @0x%" PRIx64 " val=0x%x assign: %d size: %d match: %d"
kvm_set_ioeventfd_pio(int fd, uint16_t addr, uint32_t val, bool assign, uint32_t size, bool datamatch) "fd: %d @0x%x val=0x%x assign: %d size: %d match: %d"
kvm_set_user_memory(uint32_t slot, uint32_t flags, uint64_t guest_phys_addr, uint64_t memory_size, uint64_t userspace_addr, int ret) "Slot#%d flags=0x%x gpa=0x%"PRIx64 " size=0x%"PRIx64 " ua=0x%"PRIx64 " ret=%d"
kvm_clear_dirty_log(uint32_t slot, uint64_t start, uint32_t size) "slot#%"PRId32" start 0x%"PRIx64" size 0x%"PRIx32