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From 8140691df300c06f99981832cf2f19a2e5e5d0b9 Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Sat, 11 Jan 2014 17:59:57 +0100
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Subject: [PATCH 07/22] kvm: support using KVM_MEM_READONLY flag for regions
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RH-Author: Laszlo Ersek <lersek@redhat.com>
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Message-id: <1389463208-6278-8-git-send-email-lersek@redhat.com>
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Patchwork-id: 56619
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 07/18] kvm: support using KVM_MEM_READONLY flag for regions
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Bugzilla: 1032346
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Amos Kong <akong@redhat.com>
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RH-Acked-by: Andrew Jones <drjones@redhat.com>
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From: Jordan Justen <jordan.l.justen@intel.com>
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For readonly memory regions and rom devices in romd_mode,
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we make use of the KVM_MEM_READONLY. A slot that uses
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KVM_MEM_READONLY can be read from and code can execute from the
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region, but writes will exit to qemu.
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For rom devices with !romd_mode, we force the slot to be
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removed so reads or writes to the region will exit to qemu.
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(Note that a memory region in this state is not executable
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within kvm.)
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v7:
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 * Update for readable => romd_mode rename (5f9a5ea1)
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Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
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Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> (v4)
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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> (v5)
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Message-id: 1369816047-16384-4-git-send-email-jordan.l.justen@intel.com
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Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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(cherry picked from commit 235e8982ad393e5611cb892df54881c872eea9e1)
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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---
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 kvm-all.c | 37 ++++++++++++++++++++++++++++---------
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 1 file changed, 28 insertions(+), 9 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 kvm-all.c |   37 ++++++++++++++++++++++++++++---------
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 1 files changed, 28 insertions(+), 9 deletions(-)
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diff --git a/kvm-all.c b/kvm-all.c
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index 0a70ca1..42c71b9 100644
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--- a/kvm-all.c
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+++ b/kvm-all.c
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@@ -203,12 +203,18 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot)
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     mem.slot = slot->slot;
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     mem.guest_phys_addr = slot->start_addr;
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-    mem.memory_size = slot->memory_size;
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     mem.userspace_addr = (unsigned long)slot->ram;
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     mem.flags = slot->flags;
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     if (s->migration_log) {
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         mem.flags |= KVM_MEM_LOG_DIRTY_PAGES;
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     }
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+    if (mem.flags & KVM_MEM_READONLY) {
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+        /* Set the slot size to 0 before setting the slot to the desired
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+         * value. This is needed based on KVM commit 75d61fbc. */
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+        mem.memory_size = 0;
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+        kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
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+    }
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+    mem.memory_size = slot->memory_size;
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     return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
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 }
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@@ -270,9 +276,14 @@ err:
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  * dirty pages logging control
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  */
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-static int kvm_mem_flags(KVMState *s, bool log_dirty)
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+static int kvm_mem_flags(KVMState *s, bool log_dirty, bool readonly)
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 {
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-    return log_dirty ? KVM_MEM_LOG_DIRTY_PAGES : 0;
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+    int flags = 0;
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+    flags = log_dirty ? KVM_MEM_LOG_DIRTY_PAGES : 0;
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+    if (readonly && kvm_readonly_mem_allowed) {
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+        flags |= KVM_MEM_READONLY;
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+    }
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+    return flags;
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 }
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 static int kvm_slot_dirty_pages_log_change(KVMSlot *mem, bool log_dirty)
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@@ -283,7 +294,7 @@ static int kvm_slot_dirty_pages_log_change(KVMSlot *mem, bool log_dirty)
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     old_flags = mem->flags;
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-    flags = (mem->flags & ~mask) | kvm_mem_flags(s, log_dirty);
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+    flags = (mem->flags & ~mask) | kvm_mem_flags(s, log_dirty, false);
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     mem->flags = flags;
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     /* If nothing changed effectively, no need to issue ioctl */
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@@ -601,6 +612,8 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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     int err;
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     MemoryRegion *mr = section->mr;
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     bool log_dirty = memory_region_is_logging(mr);
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+    bool writeable = !mr->readonly && !mr->rom_device;
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+    bool readonly_flag = mr->readonly || memory_region_is_romd(mr);
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     hwaddr start_addr = section->offset_within_address_space;
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     ram_addr_t size = section->size;
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     void *ram = NULL;
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@@ -620,7 +633,13 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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     }
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     if (!memory_region_is_ram(mr)) {
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-        return;
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+        if (writeable || !kvm_readonly_mem_allowed) {
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+            return;
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+        } else if (!mr->romd_mode) {
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+            /* If the memory device is not in romd_mode, then we actually want
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+             * to remove the kvm memory slot so all accesses will trap. */
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+            add = false;
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+        }
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     }
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     ram = memory_region_get_ram_ptr(mr) + section->offset_within_region + delta;
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@@ -669,7 +688,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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             mem->memory_size = old.memory_size;
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             mem->start_addr = old.start_addr;
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             mem->ram = old.ram;
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-            mem->flags = kvm_mem_flags(s, log_dirty);
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+            mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);
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             err = kvm_set_user_memory_region(s, mem);
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             if (err) {
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@@ -690,7 +709,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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             mem->memory_size = start_addr - old.start_addr;
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             mem->start_addr = old.start_addr;
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             mem->ram = old.ram;
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-            mem->flags =  kvm_mem_flags(s, log_dirty);
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+            mem->flags =  kvm_mem_flags(s, log_dirty, readonly_flag);
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             err = kvm_set_user_memory_region(s, mem);
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             if (err) {
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@@ -714,7 +733,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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             size_delta = mem->start_addr - old.start_addr;
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             mem->memory_size = old.memory_size - size_delta;
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             mem->ram = old.ram + size_delta;
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-            mem->flags = kvm_mem_flags(s, log_dirty);
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+            mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);
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             err = kvm_set_user_memory_region(s, mem);
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             if (err) {
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@@ -736,7 +755,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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     mem->memory_size = size;
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     mem->start_addr = start_addr;
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     mem->ram = ram;
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-    mem->flags = kvm_mem_flags(s, log_dirty);
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+    mem->flags = kvm_mem_flags(s, log_dirty, readonly_flag);
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     err = kvm_set_user_memory_region(s, mem);
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     if (err) {
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-- 
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1.7.1
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