Commit 8369e01c authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

kvm: port qemu-kvm's bitmap scanning 



Which is significantly faster.

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 213acd2e

kvm-all.c

+37 −16
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include "hw/hw.h"

#include "gdbstub.h"

#include "kvm.h"

#include "bswap.h"



/* KVM uses PAGE_SIZE in it's definition of COALESCED_MMIO_MAX */

#define PAGE_SIZE TARGET_PAGE_SIZE
@@ -283,10 +284,40 @@ static int kvm_set_migration_log(int enable) 
    return 0;

}



static int test_le_bit(unsigned long nr, unsigned char *addr)

/* get kvm's dirty pages bitmap and update qemu's */

static int kvm_get_dirty_pages_log_range(unsigned long start_addr,

                                         unsigned long *bitmap,

                                         unsigned long offset,

                                         unsigned long mem_size)

{

    return (addr[nr >> 3] >> (nr & 7)) & 1;

    unsigned int i, j;

    unsigned long page_number, addr, addr1, c;

    ram_addr_t ram_addr;

    unsigned int len = ((mem_size / TARGET_PAGE_SIZE) + HOST_LONG_BITS - 1) /

        HOST_LONG_BITS;



    /*

     * bitmap-traveling is faster than memory-traveling (for addr...)

     * especially when most of the memory is not dirty.

     */

    for (i = 0; i < len; i++) {

        if (bitmap[i] != 0) {

            c = leul_to_cpu(bitmap[i]);

            do {

                j = ffsl(c) - 1;

                c &= ~(1ul << j);

                page_number = i * HOST_LONG_BITS + j;

                addr1 = page_number * TARGET_PAGE_SIZE;

                addr = offset + addr1;

                ram_addr = cpu_get_physical_page_desc(addr);

                cpu_physical_memory_set_dirty(ram_addr);

            } while (c != 0);

        }

    }

    return 0;

}



#define ALIGN(x, y)  (((x)+(y)-1) & ~((y)-1))



/**

 * kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space
@@ -301,8 +332,6 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, 
{

    KVMState *s = kvm_state;

    unsigned long size, allocated_size = 0;

    target_phys_addr_t phys_addr;

    ram_addr_t addr;

    KVMDirtyLog d;

    KVMSlot *mem;

    int ret = 0;
@@ -314,7 +343,7 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, 
            break;

        }



        size = ((mem->memory_size >> TARGET_PAGE_BITS) + 7) / 8;

        size = ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS), HOST_LONG_BITS) / 8;

        if (!d.dirty_bitmap) {

            d.dirty_bitmap = qemu_malloc(size);

        } else if (size > allocated_size) {
@@ -331,17 +360,9 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, 
            break;

        }



        for (phys_addr = mem->start_addr, addr = mem->phys_offset;

             phys_addr < mem->start_addr + mem->memory_size;

             phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {

            unsigned char *bitmap = (unsigned char *)d.dirty_bitmap;

            unsigned nr = (phys_addr - mem->start_addr) >> TARGET_PAGE_BITS;



            if (test_le_bit(nr, bitmap)) {

                cpu_physical_memory_set_dirty(addr);

            }

        }

        start_addr = phys_addr;

        kvm_get_dirty_pages_log_range(mem->start_addr, d.dirty_bitmap,

                                      mem->start_addr, mem->memory_size);

        start_addr = mem->start_addr + mem->memory_size;

    }

    qemu_free(d.dirty_bitmap);