VFIO requires all of the guest's memory and IO space to be lockable in
RAM. The domain's max_balloon is the maximum amount of memory the
domain can have (in KiB). We add a generous 1GiB to that for IO space
(still much better than KVM device assignment, where the KVM module
actually *ignores* the process limits and locks everything anyway),
and convert from KiB to bytes.
In the case of hotplug, we are changing the limit for the already
existing qemu process (prlimit() is used under the hood), and for
regular commandline additions of vfio devices, we schedule a call to
setrlimit() that will happen after the qemu process is forked.
---
src/qemu/qemu_command.c | 25 ++---
src/qemu/qemu_hotplug.c | 27 ---
2 files changed, 38 insertions(+), 14 deletions(-)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 6f6b61b..2ce0672 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7906,13 +7906,24 @@ qemuBuildCommandLine(virConnectPtr conn,
if (hostdev-mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS
hostdev-source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI)
{
-if ((hostdev-source.subsys.u.pci.backend
- == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_VFIO)
-!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {
-virReportError(VIR_ERR_CONFIG_UNSUPPORTED, %s,
- _(VFIO PCI device assignment is not supported
by
- this version of qemu));
-goto error;
+if (hostdev-source.subsys.u.pci.backend
+== VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_VFIO) {
+unsigned long long memKB;
+
+if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {
+virReportError(VIR_ERR_CONFIG_UNSUPPORTED, %s,
+ _(VFIO PCI device assignment is not
+ supported by this version of qemu));
+goto error;
+}
+/* VFIO requires all of the guest's memory to be
+ * locked resident, plus some amount for IO
+ * space. Alex Williamson suggested adding 1GiB for IO
+ * space just to be safe (some finer tuning might be
+ * nice, though).
+ */
+memKB = def-mem.max_balloon + (1024 * 1024);
+virCommandSetMaxMemLock(cmd, memKB * 1024);
}
if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index f608ec4..15cca08 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -38,6 +38,7 @@
#include viralloc.h
#include virpci.h
#include virfile.h
+#include virprocess.h
#include qemu_cgroup.h
#include locking/domain_lock.h
#include network/bridge_driver.h
@@ -999,13 +1000,25 @@ int qemuDomainAttachHostPciDevice(virQEMUDriverPtr
driver,
hostdev, 1) 0)
return -1;
-if ((hostdev-source.subsys.u.pci.backend
- == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_VFIO)
-!virQEMUCapsGet(priv-qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {
-virReportError(VIR_ERR_CONFIG_UNSUPPORTED, %s,
- _(VFIO PCI device assignment is not supported by
- this version of qemu));
-goto error;
+if (hostdev-source.subsys.u.pci.backend
+== VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_VFIO) {
+unsigned long long memKB;
+
+if (!virQEMUCapsGet(priv-qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {
+virReportError(VIR_ERR_CONFIG_UNSUPPORTED, %s,
+ _(VFIO PCI device assignment is not
+ supported by this version of qemu));
+goto error;
+}
+/* VFIO requires all of the guest's memory to be locked
+ * resident, plus some amount for IO space. Alex Williamson
+ * suggested adding 1GiB for IO space just to be safe (some
+ * finer tuning might be nice, though).
+ * In this case, the guest's memory may already be locked, but
+ * it doesn't hurt to change the limit to the same value.
+ */
+memKB = vm-def-mem.max_balloon + (1024 * 1024);
+virProcessSetMaxMemLock(vm-pid, memKB * 1024);
}
if (virQEMUCapsGet(priv-qemuCaps, QEMU_CAPS_DEVICE)) {
--
1.7.11.7
--
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