From 235e8982ad393e5611cb892df54881c872eea9e1 Mon Sep 17 00:00:00 2001 From: Jordan Justen Date: Wed, 29 May 2013 01:27:26 -0700 Subject: 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: Jordan Justen Reviewed-by: Xiao Guangrong (v4) Reviewed-by: Paolo Bonzini (v5) Message-id: 1369816047-16384-4-git-send-email-jordan.l.justen@intel.com Signed-off-by: Anthony Liguori --- kvm-all.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) (limited to 'kvm-all.c') diff --git a/kvm-all.c b/kvm-all.c index 327ae12f08..8e7bbf8698 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) { -- cgit v1.2.3