How to read form a linear/virtual address?

I use the following code to dump out the memory in my debug server.

int noOfBytes;

hwaddr addr;

sscanf(command + 2, "%ld,%d", &addr, &noOfBytes);

printf("addr=%x\n", addr);

printf("noOfBytes=%d\n", noOfBytes);

uint8_t mem_buf[MAX_READ_MEMORY_SIZE + 1];

char buffer[MAX_READ_MEMORY_SIZE * 3];

if (noOfBytes > MAX_READ_MEMORY_SIZE) {

noOfBytes = MAX_READ_MEMORY_SIZE;

}

CPUArchState *cpu = first_cpu; //find_cpu(1);

cpu_single_step(cpu, sstep_flags);

cpu_memory_rw_debug(cpu, addr, mem_buf, noOfBytes, 0);