From 8140691df300c06f99981832cf2f19a2e5e5d0b9 Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Sat, 11 Jan 2014 17:59:57 +0100

Subject: [PATCH 07/22] kvm: support using KVM_MEM_READONLY flag for regions

RH-Author: Laszlo Ersek <lersek@redhat.com>

Message-id: <1389463208-6278-8-git-send-email-lersek@redhat.com>

Patchwork-id: 56619

O-Subject: [RHEL-7.0 qemu-kvm PATCH 07/18] kvm: support using KVM_MEM_READONLY flag for regions

Bugzilla: 1032346

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Amos Kong <akong@redhat.com>

RH-Acked-by: Andrew Jones <drjones@redhat.com>

From: Jordan Justen <jordan.l.justen@intel.com>

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>

(cherry picked from commit 235e8982ad393e5611cb892df54881c872eea9e1)

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

---

 kvm-all.c | 37 ++++++++++++++++++++++++++++---------

 1 file changed, 28 insertions(+), 9 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 kvm-all.c |   37 ++++++++++++++++++++++++++++---------

 1 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c

index 0a70ca1..42c71b9 100644

--- a/kvm-all.c

+++ b/kvm-all.c

@@ -203,12 +203,18 @@ 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;;

 }

@@ -270,9 +276,14 @@ 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)

@@ -283,7 +294,7 @@ 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 */

@@ -601,6 +612,8 @@ 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;

@@ -620,7 +633,13 @@ 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;

@@ -669,7 +688,7 @@ 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) {

@@ -690,7 +709,7 @@ 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) {

@@ -714,7 +733,7 @@ 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) {

@@ -736,7 +755,7 @@ 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) {

-- 

1.7.1