Commit 96c1606b33a64ea6d5e1a988f9eb234a58947002
Committed by
Anthony Liguori
Anthony Liguori
1 parent
1c7936e3
Use Little Endian for Dirty Log
We currently use host endian long types to store information in the dirty bitmap. This works reasonably well on Little Endian targets, because the u32 after the first contains the next 32 bits. On Big Endian this breaks completely though, forcing us to be inventive here. So Ben suggested to always use Little Endian, which looks reasonable. We only have dirty bitmap implemented in Little Endian targets so far and since PowerPC would be the first Big Endian platform, we can just as well switch to Little Endian always with little effort without breaking existing targets. This is the userspace part of the patch. It shouldn't change anything for existing targets, but help PowerPC. It replaces my older patch called "Use 64bit pointer for dirty log". Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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7 additions
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4 deletions
kvm-all.c
| @@ -304,6 +304,11 @@ int kvm_set_migration_log(int enable) | @@ -304,6 +304,11 @@ int kvm_set_migration_log(int enable) | ||
| 304 | return 0; | 304 | return 0; |
| 305 | } | 305 | } |
| 306 | 306 | ||
| 307 | +static int test_le_bit(unsigned long nr, unsigned char *addr) | ||
| 308 | +{ | ||
| 309 | + return (addr[nr >> 3] >> (nr & 7)) & 1; | ||
| 310 | +} | ||
| 311 | + | ||
| 307 | /** | 312 | /** |
| 308 | * kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space | 313 | * kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space |
| 309 | * This function updates qemu's dirty bitmap using cpu_physical_memory_set_dirty(). | 314 | * This function updates qemu's dirty bitmap using cpu_physical_memory_set_dirty(). |
| @@ -357,12 +362,10 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, | @@ -357,12 +362,10 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, | ||
| 357 | for (phys_addr = mem->start_addr, addr = mem->phys_offset; | 362 | for (phys_addr = mem->start_addr, addr = mem->phys_offset; |
| 358 | phys_addr < mem->start_addr + mem->memory_size; | 363 | phys_addr < mem->start_addr + mem->memory_size; |
| 359 | phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) { | 364 | phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) { |
| 360 | - uint64_t *bitmap = (uint64_t *)d.dirty_bitmap; | 365 | + unsigned char *bitmap = (unsigned char *)d.dirty_bitmap; |
| 361 | unsigned nr = (phys_addr - mem->start_addr) >> TARGET_PAGE_BITS; | 366 | unsigned nr = (phys_addr - mem->start_addr) >> TARGET_PAGE_BITS; |
| 362 | - unsigned word = nr / (sizeof(*bitmap) * 8); | ||
| 363 | - unsigned bit = nr % (sizeof(*bitmap) * 8); | ||
| 364 | 367 | ||
| 365 | - if ((bitmap[word] >> bit) & 1) { | 368 | + if (test_le_bit(nr, bitmap)) { |
| 366 | cpu_physical_memory_set_dirty(addr); | 369 | cpu_physical_memory_set_dirty(addr); |
| 367 | } else if (r < 0) { | 370 | } else if (r < 0) { |
| 368 | /* When our KVM implementation doesn't know about dirty logging | 371 | /* When our KVM implementation doesn't know about dirty logging |