Commit e81bcda5 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

exec: make qemu_ram_ptr_length more similar to qemu_get_ram_ptr 



Notably, use qemu_get_ram_block to enjoy the MRU optimization.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 49b24afc

exec.c

+23 −23
Original line number Diff line number Diff line
@@ -1809,36 +1809,33 @@ void *qemu_get_ram_ptr(ram_addr_t addr) 
/* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr

 * but takes a size argument.

 *

 * By the time this function returns, the returned pointer is not protected

 * by RCU anymore.  If the caller is not within an RCU critical section and

 * does not hold the iothread lock, it must have other means of protecting the

 * pointer, such as a reference to the region that includes the incoming

 * ram_addr_t.

 * Called within RCU critical section.

 */

static void *qemu_ram_ptr_length(ram_addr_t addr, hwaddr *size)

{

    void *ptr;

    RAMBlock *block;

    ram_addr_t offset_inside_block;

    if (*size == 0) {

        return NULL;

    }

    if (xen_enabled()) {



    block = qemu_get_ram_block(addr);

    offset_inside_block = addr - block->offset;

    *size = MIN(*size, block->max_length - offset_inside_block);



    if (xen_enabled() && block->host == NULL) {

        /* We need to check if the requested address is in the RAM

         * because we don't want to map the entire memory in QEMU.

         * In that case just map the requested area.

         */

        if (block->offset == 0) {

            return xen_map_cache(addr, *size, 1);

    } else {

        RAMBlock *block;

        rcu_read_lock();

        QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {

            if (addr - block->offset < block->max_length) {

                if (addr - block->offset + *size > block->max_length)

                    *size = block->max_length - addr + block->offset;

                ptr = ramblock_ptr(block, addr - block->offset);

                rcu_read_unlock();

                return ptr;

            }

        }



        fprintf(stderr, "Bad ram offset %" PRIx64 "\n", (uint64_t)addr);

        abort();

        block->host = xen_map_cache(block->offset, block->max_length, 1);

    }



    return ramblock_ptr(block, offset_inside_block);

}



/*
@@ -2786,6 +2783,7 @@ void *address_space_map(AddressSpace *as, 
    hwaddr l, xlat, base;

    MemoryRegion *mr, *this_mr;

    ram_addr_t raddr;

    void *ptr;



    if (len == 0) {

        return NULL;
@@ -2837,9 +2835,11 @@ void *address_space_map(AddressSpace *as, 
    }



    memory_region_ref(mr);

    rcu_read_unlock();

    *plen = done;

    return qemu_ram_ptr_length(raddr + base, plen);

    ptr = qemu_ram_ptr_length(raddr + base, plen);

    rcu_read_unlock();



    return ptr;

}



/* Unmaps a memory region previously mapped by address_space_map().