On Thu, Mar 12, 2020 at 3:00 AM Daniel Henrique Barboza <danielhb413@gmail.com> wrote:
Using the 'uuid' element for ppc64 NVDIMM memory added in the previous patch, use it in qemuBuildMemoryDeviceStr() to pass it over to QEMU.
Another ppc64 restriction is the necessity of a mem->labelsize, given than ppc64 only support label-area backed NVDIMMs.
Finally, we don't want ppc64 NVDIMMs to align up due to the high risk of going beyond the end of file with a 256MiB increment that the user didn't predict. Align it down instead.
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> ---
...
+static void +qemuDomainNVDimmAlignSizePseries(virDomainDefPtr def, + virDomainMemoryDefPtr mem) +{ + /* For NVDIMMs in ppc64 in we want to align down the guest + * visible space, instead of align up, to avoid writing + * beyond the end of file by adding a potential 256MiB + * to the user specified size. + * + * The label-size is mandatory for ppc64 as well, meaning that + * the guest visible space will be target_size-label_size. + * + * Finally, target_size must include label_size. + * + * The above can be summed up as follows: + * + * target_size = AlignDown(target_size - label_size) + label_size + */ + unsigned long long ppc64AlignSize = qemuDomainGetMemorySizeAlignment(def); + unsigned long long guestArea = mem->size - mem->labelsize; + + /* Align down guest_area. 256MiB is the minimum size. */ + guestArea = (guestArea/ppc64AlignSize) * ppc64AlignSize; + guestArea = MAX(guestArea, ppc64AlignSize);
The math is correct, but we need additional checks when a backing file of size less than 256MB is attempted to be hot-plugged. The qemu errors out like below if the backing file is 240MB and MAX of (240, 256) is chosen. -object memory-backend-file,id=memnvdimm1,prealloc=yes,mem-path =/tmp/nvdimm,share=yes,size=268566528: backing store size 0xf000000 does not match 'size' option 0x10020000
+ + mem->size = guestArea + mem->labelsize; +} + +.... + </label> </target> <address type='dimm' slot='0'/> </memory> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 35d413d40b..077f7e7650 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -2790,6 +2790,10 @@ mymain(void) DO_TEST_CAPS_LATEST("memory-hotplug-nvdimm-align"); DO_TEST_CAPS_LATEST("memory-hotplug-nvdimm-pmem"); DO_TEST_CAPS_LATEST("memory-hotplug-nvdimm-readonly"); + DO_TEST("memory-hotplug-nvdimm-ppc64", QEMU_CAPS_KVM, QEMU_CAPS_DEVICE_NVDIMM,
I see the qemucapabilitiesdata/caps-5*.ppc64* not updated with the nvdimm support. Can you update it as well? Then this can be changed to just DO_TEST_CAPS_LATEST_PPC64, without this elaborate list of caps.
+ QEMU_CAPS_NUMA, QEMU_CAPS_DEVICE_SPAPR_PCI_HOST_BRIDGE, + QEMU_CAPS_OBJECT_MEMORY_RAM, ...
Thanks, Shiva