Commit 235e8982 authored by Jordan Justen's avatar Jordan Justen Committed by Anthony Liguori
Browse files

kvm: support using KVM_MEM_READONLY flag for regions 



For readonly memory regions and rom devices in romd_mode,
we make use of the KVM_MEM_READONLY. A slot that uses
KVM_MEM_READONLY can be read from and code can execute from the
region, but writes will exit to qemu.

For rom devices with !romd_mode, we force the slot to be
removed so reads or writes to the region will exit to qemu.
(Note that a memory region in this state is not executable
within kvm.)

v7:
 * Update for readable => romd_mode rename (5f9a5ea1)

Signed-off-by: default avatarJordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> (v4)
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> (v5)
Message-id: 1369816047-16384-4-git-send-email-jordan.l.justen@intel.com
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent df9c8b75

kvm-all.c

+28 −9
Original line number Diff line number Diff line
@@ -201,12 +201,18 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot) 


    mem.slot = slot->slot;

    mem.guest_phys_addr = slot->start_addr;

    mem.memory_size = slot->memory_size;

    mem.userspace_addr = (unsigned long)slot->ram;

    mem.flags = slot->flags;

    if (s->migration_log) {

        mem.flags |= KVM_MEM_LOG_DIRTY_PAGES;

    }

    if (mem.flags & KVM_MEM_READONLY) {

        /* Set the slot size to 0 before setting the slot to the desired

         * value. This is needed based on KVM commit 75d61fbc. */

        mem.memory_size = 0;

        kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);

    }

    mem.memory_size = slot->memory_size;

    return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);

}
@@ -268,9 +274,14 @@ err: 
 * dirty pages logging control

 */



static int kvm_mem_flags(KVMState *s, bool log_dirty)

static int kvm_mem_flags(KVMState *s, bool log_dirty, bool readonly)

{

    return log_dirty ? KVM_MEM_LOG_DIRTY_PAGES : 0;

    int flags = 0;

    flags = log_dirty ? KVM_MEM_LOG_DIRTY_PAGES : 0;

    if (readonly && kvm_readonly_mem_allowed) {

        flags |= KVM_MEM_READONLY;

    }

    return flags;

}



static int kvm_slot_dirty_pages_log_change(KVMSlot *mem, bool log_dirty)
@@ -281,7 +292,7 @@ static int kvm_slot_dirty_pages_log_change(KVMSlot *mem, bool log_dirty) 


    old_flags = mem->flags;



    flags = (mem->flags & ~mask) | kvm_mem_flags(s, log_dirty);

    flags = (mem->flags & ~mask) | kvm_mem_flags(s, log_dirty, false);

    mem->flags = flags;



    /* If nothing changed effectively, no need to issue ioctl */
@@ -619,6 +630,8 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
    int err;

    MemoryRegion *mr = section->mr;

    bool log_dirty = memory_region_is_logging(mr);

    bool writeable = !mr->readonly && !mr->rom_device;

    bool readonly_flag = mr->readonly || memory_region_is_romd(mr);

    hwaddr start_addr = section->offset_within_address_space;

    ram_addr_t size = section->size;

    void *ram = NULL;
@@ -638,7 +651,13 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
    }



    if (!memory_region_is_ram(mr)) {

        if (writeable || !kvm_readonly_mem_allowed) {

            return;

        } else if (!mr->romd_mode) {

            /* If the memory device is not in romd_mode, then we actually want

             * to remove the kvm memory slot so all accesses will trap. */

            add = false;

        }

    }



    ram = memory_region_get_ram_ptr(mr) + section->offset_within_region + delta;
@@ -687,7 +706,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
            mem->memory_size = old.memory_size;

            mem->start_addr = old.start_addr;

            mem->ram = old.ram;

            mem->flags = kvm_mem_flags(s, log_dirty);

            mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);



            err = kvm_set_user_memory_region(s, mem);

            if (err) {
@@ -708,7 +727,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
            mem->memory_size = start_addr - old.start_addr;

            mem->start_addr = old.start_addr;

            mem->ram = old.ram;

            mem->flags =  kvm_mem_flags(s, log_dirty);

            mem->flags =  kvm_mem_flags(s, log_dirty, readonly_flag);



            err = kvm_set_user_memory_region(s, mem);

            if (err) {
@@ -732,7 +751,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
            size_delta = mem->start_addr - old.start_addr;

            mem->memory_size = old.memory_size - size_delta;

            mem->ram = old.ram + size_delta;

            mem->flags = kvm_mem_flags(s, log_dirty);

            mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);



            err = kvm_set_user_memory_region(s, mem);

            if (err) {
@@ -754,7 +773,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add) 
    mem->memory_size = size;

    mem->start_addr = start_addr;

    mem->ram = ram;

    mem->flags = kvm_mem_flags(s, log_dirty);

    mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);



    err = kvm_set_user_memory_region(s, mem);

    if (err) {