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kvm: support using KVM_MEM_READONLY flag for regions

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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: Jordan 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: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Jordan Justen 2013-05-29 01:27:26 -07:00 committed by Anthony Liguori
parent df9c8b758a
commit 235e8982ad
1 changed files with 28 additions and 9 deletions
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37
kvm-all.c
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@ -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)) {
return;
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) {