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.jus...@intel.com>
Reviewed-by: Xiao Guangrong <xiaoguangr...@linux.vnet.ibm.com> (v4)
Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> (v5)
---
kvm-all.c | 37 ++++++++++++++++++++++++++++---------
1 file changed, 28 insertions(+), 9 deletions(-)
diff --git a/kvm-all.c b/kvm-all.c
index 327ae12..8e7bbf8 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -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) {
--
1.7.10.4
