From 598ec0db685eb63c99fcb7905ffd73bb714f1cf4 Mon Sep 17 00:00:00 2001
From: Jiri Denemark <jdenemar@redhat.com>
Date: Tue, 13 Aug 2019 15:17:36 +0200
Subject: [PATCH] qemu: Check for drop-cache capability

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@redhat.com>
Acked-By: Peter Krempa <pkrempa@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..68ef6c49b4 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 type='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>