[libvirt] [PATCH v3 19/30] qemu: Take NVMe disks into account when calculating memlock limit

[Michal Privoznik]

We have this beautiful function that does crystal ball
divination. The function is named
qemuDomainGetMemLockLimitBytes() and it calculates the upper
limit of how much locked memory is given guest going to need. The
function bases its guess on devices defined for a domain. For
instance, if there is a VFIO hostdev defined then it adds 1GiB to
the guessed maximum. Since NVMe disks are pretty much VFIO
hostdevs (but not quite), we have to do the same sorcery.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
ACKed-by: Peter Krempa <pkrempa at redhat.com>
---
 src/qemu/qemu_domain.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 59e98de2d2..7b515b9520 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -11920,6 +11920,9 @@ getPPC64MemLockLimitBytes(virDomainDefPtr def)
         }
     }
 
+    if (virDomainDefHasNVMeDisk(def))
+        usesVFIO = true;
+
     memory = virDomainDefGetMemoryTotal(def);
 
     if (def->mem.max_memory)
@@ -12018,6 +12021,7 @@ unsigned long long
 qemuDomainGetMemLockLimitBytes(virDomainDefPtr def)
 {
     unsigned long long memKB = 0;
+    bool usesVFIO = false;
     size_t i;
 
     /* prefer the hard limit */
@@ -12058,11 +12062,17 @@ qemuDomainGetMemLockLimitBytes(virDomainDefPtr def)
     for (i = 0; i < def->nhostdevs; i++) {
         if (virHostdevIsVFIODevice(def->hostdevs[i]) ||
             virHostdevIsMdevDevice(def->hostdevs[i])) {
-            memKB = virDomainDefGetMemoryTotal(def) + 1024 * 1024;
-            goto done;
+            usesVFIO = true;
+            break;
         }
     }
 
+    if (virDomainDefHasNVMeDisk(def))
+        usesVFIO = true;
+
+    if (usesVFIO)
+        memKB = virDomainDefGetMemoryTotal(def) + 1024 * 1024;
+
  done:
     return memKB << 10;
 }
-- 
2.23.0