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[Qemu-devel] [PATCH v2 0/5] Qemu: implement readonly memory
From: |
Xiao Guangrong |
Subject: |
[Qemu-devel] [PATCH v2 0/5] Qemu: implement readonly memory |
Date: |
Thu, 25 Oct 2012 17:20:34 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 |
This patch set make the readonly memory in qemu really readonly by using
readonly memory slots feature in kvm to make qemu-kvm safer. Memory
regions with readonly property would be plug into kvm as readonly memory
slots.
Below module can test this feature:
static int rom_tester_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
struct resource *res = &dev->resource[PCI_ROM_RESOURCE];
char buf[6];
size_t rom_size;
char * __iomem map;
int i;
if (res->flags & (IORESOURCE_ROM_SHADOW | IORESOURCE_ROM_COPY |
IORESOURCE_ROM_BIOS_COPY)) {
dev_printk(KERN_INFO, &dev->dev, "skip ROM COPY.\n");
return 0;
}
if (res->flags &
(IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
dev_printk(KERN_INFO, &dev->dev, "rom tester\n");
if (pci_enable_rom(dev)) {
dev_printk(KERN_INFO, &dev->dev, "do not found Rom\n");
goto exit;
}
map = pci_map_rom(dev, &rom_size);
if (!map) {
dev_printk(KERN_INFO, &dev->dev, "map rom fail.\n");
goto disable_exit;
}
dev_printk(KERN_INFO, &dev->dev, "Rom map: %p [size: %lx],
phsyc:%llx.\n",
map, rom_size, pci_resource_start(dev, PCI_ROM_RESOURCE));
if (rom_size < 6) {
printk("map size < 6.\n");
goto unmap_exit;
}
printk("The first 6 bytes:\n");
for (i = 0; i < 6; i++) {
buf[i] = map[i];
printk("%x ", buf[i]);
}
printk("\n\n");
memcpy(map, "KVMKVM", 6);
if (!memcmp(map, "KVMKVM", 6)) {
printk("Rom Test: fail.\n");
goto unmap_exit;
}
for (i = 0; i < 6; i++)
if (buf[i] != ((char *)map)[i]) {
printk("The %d byte is changed: %x -> %x.\n",
i, buf[i], map[i]);
printk("Rom Test: fail.\n");
goto unmap_exit;
}
printk("Rom Test: Okay.\n");
unmap_exit:
pci_unmap_rom(dev, map);
disable_exit:
pci_disable_rom(dev);
exit:
return 0;
}
static DEFINE_PCI_DEVICE_TABLE(rom_tester_tbl) = {
{ PCI_DEVICE(PCI_ANY_ID, PCI_ANY_ID)},
{0,} /* 0 terminated list. */
};
MODULE_DEVICE_TABLE(pci, rom_tester_tbl);
static struct pci_driver rom_tester = {
.name = "pci-rom-tester",
.id_table = rom_tester_tbl,
.probe = rom_tester_probe,
};
static int __init pci_rom_test_init(void)
{
int rc;
rc = pci_register_driver(&rom_tester);
if (rc)
return rc;
return 0;
}
static void __exit pci_rom_test_exit(void)
{
pci_unregister_driver(&rom_tester);
}
module_init(pci_rom_test_init);
module_exit(pci_rom_test_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Xiao Guangrong <address@hidden>");
we test it with the rom of Intel 82540EM Gigabit Ethernet Controller.
0. start qemu:
qemu-system-x86_64 -enable-kvm -m 1G -smp 2 -hda fedora16.qcow2 \
-nic nic,model=e1000,vlan=1,macadrr=52:00:12:34:56 \
-net user,vlan=1
1. unbind the device:
echo "0000:00:03.0" > /sys/bus/pci/devices/0000\:00\:03.0/driver/unbind
2. install the test kernel module, here we name it write_rom:
modprobe write_rom
3. print dmesg to verify the result is ok or fail:
dmesg
4. remove the test kernel module.
rmmod write_rom
5. rebind the device to its driver, test if the nic still works:
echo "0000:00:03.0" > /sys/bus/pci/drivers/e1000/bind
open firefox and try some web page.
when I use kvm without readonly memory slot, in step 2 it reports:
Rom Test: fail. this means we can write to the memory region of a rom,
which is quite not safe for the guest and host.
when I use kvm with readonly memory slot, in step 2 it reports:
Rom Test: Okay.
this means write operation is not successful, and return back to qemu from kvm.
thus we can make the rom real rom.
- [Qemu-devel] [PATCH v2 0/5] Qemu: implement readonly memory,
Xiao Guangrong <=
- [Qemu-devel] [PATCH v2 1/5] KVM: define KVM_CAP_READONLY_MEM unconditionally, Xiao Guangrong, 2012/10/25
- [Qemu-devel] [PATCH v2 4/5] Qemu: implement readonly memory, Xiao Guangrong, 2012/10/25
- [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Xiao Guangrong, 2012/10/25
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Jan Kiszka, 2012/10/26
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Xiao Guangrong, 2012/10/29
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Jan Kiszka, 2012/10/29
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Xiao Guangrong, 2012/10/29
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Jan Kiszka, 2012/10/31
- Re: [Qemu-devel] [PATCH v2 3/5] Qemu: do not mark bios readonly, Xiao Guangrong, 2012/10/31