[libvirt] [PATCH 2/3] qemu: Check for drop-cache capability

[Jiri Denemark]

QEMU 4.0.0 and newer automatically drops caches at the end of migration.
Let's check for this capability so that we can allow migration when disk
cache is turned on.

Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
 src/qemu/qemu_capabilities.c                      | 2 ++
 src/qemu/qemu_capabilities.h                      | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml   | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml   | 1 +
 tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml  | 1 +
 tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml  | 1 +
 9 files changed, 10 insertions(+)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 405bc3f288..c9677315ab 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -536,6 +536,7 @@ VIR_ENUM_IMPL(virQEMUCaps,
 
               /* 335 */
               "bochs-display",
+              "migration-file-drop-cache",
     );
 
 
@@ -1279,6 +1280,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsQMPSchemaQueries[] = {
     { "query-iothreads/ret-type/poll-max-ns", QEMU_CAPS_IOTHREAD_POLLING },
     { "query-display-options/ret-type/+egl-headless/rendernode", QEMU_CAPS_EGL_HEADLESS_RENDERNODE },
     { "nbd-server-add/arg-type/bitmap", QEMU_CAPS_NBD_BITMAP },
+    { "blockdev-add/arg-type/+file/drop-cache", QEMU_CAPS_MIGRATION_FILE_DROP_CACHE },
 };
 
 typedef struct _virQEMUCapsObjectTypeProps virQEMUCapsObjectTypeProps;
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index d7c6df20c7..6db0f28a5f 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -517,6 +517,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */
 
     /* 335 */
     QEMU_CAPS_DEVICE_BOCHS_DISPLAY, /* -device bochs-display */
+    QEMU_CAPS_MIGRATION_FILE_DROP_CACHE, /* migration with disk cache on is safe for typ='file' disks */
 
     QEMU_CAPS_LAST /* this must always be the last item */
 } virQEMUCapsFlags;
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml b/tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml
index 8fe369f518..20f119665b 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml
@@ -164,6 +164,7 @@
   <flag name='bitmap-merge'/>
   <flag name='nbd-bitmap'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>61700758</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml b/tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml
index 2df230c4f7..9ea6f4d046 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml
@@ -169,6 +169,7 @@
   <flag name='bitmap-merge'/>
   <flag name='nbd-bitmap'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>42900758</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml b/tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml
index f4acda457a..7503c2dbcd 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml
@@ -167,6 +167,7 @@
   <flag name='bitmap-merge'/>
   <flag name='nbd-bitmap'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>0</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml b/tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml
index e71d83ee06..4a94179ee7 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml
@@ -167,6 +167,7 @@
   <flag name='bitmap-merge'/>
   <flag name='nbd-bitmap'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>0</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml b/tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml
index a1ac2587a0..ef802f3d1f 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml
@@ -131,6 +131,7 @@
   <flag name='query-current-machine'/>
   <flag name='bitmap-merge'/>
   <flag name='nbd-bitmap'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>39100758</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml b/tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml
index 1d44a5a1ba..87c95f4d18 100644
--- a/tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml
+++ b/tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml
@@ -206,6 +206,7 @@
   <flag name='nbd-bitmap'/>
   <flag name='x86-max-cpu'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>43100758</microcodeVersion>
diff --git a/tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml b/tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml
index f336aeb48c..f4583d7fe7 100644
--- a/tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml
+++ b/tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml
@@ -208,6 +208,7 @@
   <flag name='cpu-unavailable-features'/>
   <flag name='canonical-cpu-features'/>
   <flag name='bochs-display'/>
+  <flag name='migration-file-drop-cache'/>
   <version>4000050</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>43100759</microcodeVersion>
-- 
2.22.1