On 01.11.23 02:29, Ani Sinha wrote:
On 27-Oct-2023, at 4:12 PM, Ani Sinha <anisi...@redhat.com> wrote:
QEMU has validations to make sure that a VM is not started with more memory
(static and hotpluggable memory) than what the guest processor can address
directly with its addressing bits. This change adds a test to make sure QEMU
fails to start with a specific error message when an attempt is made to
start a VM with more memory than what the processor can directly address.
The test also checks for passing cases when the address space of the processor
is capable of addressing all memory. Boundary cases are tested.
CC: imamm...@redhat.com
CC: David Hildenbrand <da...@redhat.com>
Signed-off-by: Ani Sinha <anisi...@redhat.com>
Gentle ping on this. David does these tests look good and cover all cases more
or less?
Hi,
sorry, for some reason the patches never made it to my inbox.
---
tests/avocado/mem-addr-space-check.py | 331 ++++++++++++++++++++++++++
1 file changed, 331 insertions(+)
create mode 100644 tests/avocado/mem-addr-space-check.py
Changelog:
v3: added pae tests as well.
v2: added 64-bit tests. Added cxl tests.
Sample run:
$ ./pyvenv/bin/avocado run tests/avocado/mem-addr-space-check.py --tap -
1..14
ok 1 tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_pse36
ok 2 tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_pae
ok 3
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_pentium_pse36
ok 4
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_pentium_pae
ok 5 tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_pentium2
ok 6
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_nonpse36
ok 7
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_tcg_q35_70_amd
ok 8
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_tcg_q35_71_amd
ok 9
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_tcg_q35_70_amd
ok 10
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_tcg_q35_71_amd
ok 11
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_tcg_q35_71_intel
ok 12
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_tcg_q35_71_amd_41bits
ok 13
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_low_tcg_q35_intel_cxl
ok 14
tests/avocado/mem-addr-space-check.py:MemAddrCheck.test_phybits_ok_tcg_q35_intel_cxl
diff --git a/tests/avocado/mem-addr-space-check.py
b/tests/avocado/mem-addr-space-check.py
new file mode 100644
index 0000000000..6ded11d658
--- /dev/null
+++ b/tests/avocado/mem-addr-space-check.py
@@ -0,0 +1,331 @@
+# Check for crash when using memory beyond the available guest processor
+# address space.
+#
+# Copyright (c) 2023 Red Hat, Inc.
+#
+# Author:
+# Ani Sinha <anisi...@redhat.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+from avocado_qemu import QemuSystemTest
+import signal
+
+class MemAddrCheck(QemuSystemTest):
+ # first, lets test some 32-bit processors.
+ # for all 32-bit cases, pci64_hole_size is 0.
+ def test_phybits_low_pse36(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ With pse36 feature ON, a processor has 36 bits of addressing. So it can
+ access up to a maximum of 64GiB of memory. Memory hotplug region begins
+ at 4 GiB boundary when "above_4g_mem_size" is 0 (this would be true
when
+ we have 0.5 GiB of VM memory, see pc_q35_init()). This means total
+ hotpluggable memory size is 60 GiB. Per slot, we reserve 1 GiB of
memory
+ for dimm alignment for all newer machines (see enforce_aligned_dimm
+ property for pc machines and pc_get_device_memory_range()). That leaves
+ total hotpluggable actual memory size of 59 GiB. If the VM is started
+ with 0.5 GiB of memory, maxmem should be set to a maximum value of
+ 59.5 GiB to ensure that the processor can address all memory directly.
+ Note that 64-bit pci hole size is 0 in this case. If maxmem is set to
+ 59.6G, QEMU should fail to start with a message "phy-bits are too low".
+ If maxmem is set to 59.5G with all other QEMU parameters identical,
QEMU
+ should start fine.
+ """
+ self.vm.add_args('-S', '-machine', 'q35', '-m',
+ '512,slots=1,maxmem=59.6G',
+ '-cpu', 'pentium,pse36=on', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
Just a note that for virtio-mem, you don't even have to reserve an (ACPI
NVDIMM/DIMM) slot.
So you might get away just setting "slots=0" and using maxmem=60.6G,
making it possible to simplify the comment(s) a bit (and all the other test
cases).
Otherwise, maybe clearer use a DIMM instead of a virtio-mem device.
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.wait()
+ self.assertEquals(self.vm.exitcode(), 1, "QEMU exit code should be 1")
+ self.assertRegex(self.vm.get_log(), r'phys-bits too low')
+
+ def test_phybits_low_pae(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ With pae feature ON, a processor has 36 bits of addressing. So it can
+ access up to a maximum of 64GiB of memory. Rest is the same as the case
+ with pse36 above.
+ """
+ self.vm.add_args('-S', '-machine', 'q35', '-m',
+ '512,slots=1,maxmem=59.6G',
+ '-cpu', 'pentium,pae=on', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
Same considerations.
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.wait()
+ self.assertEquals(self.vm.exitcode(), 1, "QEMU exit code should be 1")
+ self.assertRegex(self.vm.get_log(), r'phys-bits too low')
+
+ def test_phybits_ok_pentium_pse36(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ Setting maxmem to 59.5G and making sure that QEMU can start with the
+ same options as the failing case above with pse36 cpu feature.
+ """
+ self.vm.add_args('-machine', 'q35', '-m',
+ '512,slots=1,maxmem=59.5G',
+ '-cpu', 'pentium,pse36=on', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.shutdown()
+ self.assertEquals(self.vm.exitcode(), -signal.SIGTERM,
+ "QEMU did not terminate gracefully upon SIGTERM")
+
+ def test_phybits_ok_pentium_pae(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ Test is same as above but now with pae CPUID turned on. Setting
s/CPUID/cpu feture/ ?
+ maxmem to 59.5G and making sure that QEMU can start fine with the
+ same options as the case above.
+ """
+ self.vm.add_args('-machine', 'q35', '-m',
+ '512,slots=1,maxmem=59.5G',
+ '-cpu', 'pentium,pae=on', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.shutdown()
+ self.assertEquals(self.vm.exitcode(), -signal.SIGTERM,
+ "QEMU did not terminate gracefully upon SIGTERM")
+
+ def test_phybits_ok_pentium2(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ Pentium2 has 36 bits of addressing, so its same as pentium
+ with pse36 ON.
+ """
+ self.vm.add_args('-machine', 'q35', '-m',
+ '512,slots=1,maxmem=59.5G',
+ '-cpu', 'pentium2', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.shutdown()
+ self.assertEquals(self.vm.exitcode(), -signal.SIGTERM,
+ "QEMU did not terminate gracefully upon SIGTERM")
+
+ def test_phybits_low_nonpse36(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ Pentium processor has 32 bits of addressing without pse36 or pae
+ so it can access up to 4 GiB of memory. Setting maxmem to 4GiB
"access physical addresses up to 4 GiB"
+ should make QEMU fail to start with "phys-bits too low" message.
"because the region for memory hotplug is always placed above 4 GiB due to the
PCI hole and simplicity."
+ """
+ self.vm.add_args('-S', '-machine', 'q35', '-m',
+ '512,slots=1,maxmem=4G',
+ '-cpu', 'pentium', '-display', 'none',
+ '-object', 'memory-backend-ram,id=mem1,size=1G',
+ '-device', 'virtio-mem-pci,id=vm0,memdev=mem1')
+ self.vm.set_qmp_monitor(enabled=False)
+ self.vm.launch()
+ self.vm.wait()
+ self.assertEquals(self.vm.exitcode(), 1, "QEMU exit code should be 1")
+ self.assertRegex(self.vm.get_log(), r'phys-bits too low')
+
+ # now lets test some 64-bit CPU cases.
+ def test_phybits_low_tcg_q35_70_amd(self):
+ """
+ :avocado: tags=machine:q35
+ :avocado: tags=arch:x86_64
+
+ For q35 7.1 machines and above, "above_4G" memory starts at 1 TiB
+ boundary for AMD cpus (default). Lets test without that case.
^ first time I hear about that. Weird AMD-specific stuff, really.
/*
* The HyperTransport range close to the 1T boundary is unique to AMD
* hosts with IOMMUs enabled. Restrict the ram-above-4g relocation
* to above 1T to AMD vCPUs only. @enforce_amd_1tb_hole is only false in
* older machine types (<= 7.0) for compatibility purposes.
*/
if (IS_AMD_CPU(&cpu->env) && pcmc->enforce_amd_1tb_hole) {
/* Bail out if max possible address does not cross HT range */
if (pc_max_used_gpa(pcms, pci_hole64_size) >= AMD_HT_START) {
x86ms->above_4g_mem_start = AMD_ABOVE_1TB_START;
So there is a fixed memory hole that starts at 0xfd00000000UL. If our max GPA
would
overlap that region, we'll place everything above that memory hole.
}
/*
* Advertise the HT region if address space covers the reserved
* region or if we relocate.
*/
if (cpu->phys_bits >= 40) {
e820_add_entry(AMD_HT_START, AMD_HT_SIZE, E820_RESERVED);
}
}
I don't think your desciption is quite correct for that case. "above_4G" only
starts above
1 TiB if it would overlap that special memory hole starting at 0xfd00000000UL.
--
Cheers,
David / dhildenb