[libvirt PATCHv2 3/5] qemu: fill capabilities for virtiofsd

[Ján Tomko <jtomko@xxxxxxxxxx>]

Run the daemon with --print-capabilities first, to see what it supports.

Signed-off-by: Ján Tomko <jtomko@xxxxxxxxxx>
---
 src/conf/domain_conf.h     |  1 +
 src/qemu/qemu_vhost_user.c | 60 ++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_vhost_user.h | 12 ++++++++
 src/qemu/qemu_virtiofs.c   |  9 ++++--
 4 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 2818a9f1f5..b3a0d26cde 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -899,6 +899,7 @@ struct _virDomainFSDef {
     virDomainIdMapDef idmap;
     virDomainVirtioOptions *virtio;
     virObject *privateData;
+    virBitmap *caps;
 };
 
 
diff --git a/src/qemu/qemu_vhost_user.c b/src/qemu/qemu_vhost_user.c
index 0294daab80..30a60db528 100644
--- a/src/qemu/qemu_vhost_user.c
+++ b/src/qemu/qemu_vhost_user.c
@@ -22,6 +22,7 @@
 
 #include "qemu_vhost_user.h"
 #include "qemu_interop_config.h"
+#include "virbitmap.h"
 #include "virjson.h"
 #include "virlog.h"
 #include "viralloc.h"
@@ -90,6 +91,12 @@ VIR_ENUM_IMPL(qemuVhostUserGPUFeature,
               "render-node",
 );
 
+VIR_ENUM_IMPL(qemuVhostUserFSFeature,
+              QEMU_VHOST_USER_FS_FEATURE_LAST,
+              "migrate-precopy",
+              "separate-options",
+);
+
 typedef struct _qemuVhostUserGPU qemuVhostUserGPU;
 struct _qemuVhostUserGPU {
     size_t nfeatures;
@@ -414,6 +421,53 @@ qemuVhostUserFillDomainGPU(virQEMUDriver *driver,
     return ret;
 }
 
+int
+qemuVhostUserFillFSCapabilities(virBitmap **caps,
+                                const char *binary,
+                                bool reportError G_GNUC_UNUSED)
+{
+    g_autoptr(virJSONValue) doc = NULL;
+    g_autofree char *output = NULL;
+    g_autoptr(virCommand) cmd = NULL;
+    virJSONValue *featuresJSON;
+    size_t nfeatures;
+    size_t i;
+    g_autoptr(virBitmap) features = NULL;
+
+    cmd = virCommandNewArgList(binary, "--print-capabilities", NULL);
+    virCommandSetOutputBuffer(cmd, &output);
+    if (virCommandRun(cmd, NULL) < 0)
+        return -2;
+
+    if (!(doc = virJSONValueFromString(output))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unable to parse json capabilities '%1$s'"),
+                       binary);
+        return -1;
+    }
+
+    /* Older virtiofsd did not print any features */
+    if (!(featuresJSON = virJSONValueObjectGetArray(doc, "features")))
+        return 0;
+
+    features = virBitmapNew(0);
+    nfeatures = virJSONValueArraySize(featuresJSON);
+
+    for (i = 0; i < nfeatures; i++) {
+        virJSONValue *item = virJSONValueArrayGet(featuresJSON, i);
+        const char *tmpStr = virJSONValueGetString(item);
+        int tmp;
+
+        if ((tmp = qemuVhostUserFSFeatureTypeFromString(tmpStr)) < 0) {
+            VIR_DEBUG("ignoring unknown virtiofs feature '%s'", tmpStr);
+            continue;
+        }
+        virBitmapSetBitExpand(features, tmp);
+    }
+
+    *caps = g_steal_pointer(&features);
+    return 0;
+}
 
 int
 qemuVhostUserFillDomainFS(virQEMUDriver *driver,
@@ -435,6 +489,12 @@ qemuVhostUserFillDomainFS(virQEMUDriver *driver,
             continue;
 
         fs->binary = g_strdup(vu->binary);
+
+        /* skip binaries that can't report their capabilities */
+        if (qemuVhostUserFillFSCapabilities(&fs->caps,
+                                            vu->binary,
+                                            false) == -1)
+            continue;
         break;
     }
 
diff --git a/src/qemu/qemu_vhost_user.h b/src/qemu/qemu_vhost_user.h
index d1aa6ca189..f9cd549d5d 100644
--- a/src/qemu/qemu_vhost_user.h
+++ b/src/qemu/qemu_vhost_user.h
@@ -46,3 +46,15 @@ qemuVhostUserFillDomainGPU(virQEMUDriver *driver,
 int
 qemuVhostUserFillDomainFS(virQEMUDriver *driver,
                           virDomainFSDef *fs);
+
+int
+qemuVhostUserFillFSCapabilities(virBitmap **caps,
+                                const char *binary,
+                                bool reportError);
+typedef enum {
+    QEMU_VHOST_USER_FS_FEATURE_MIGRATE_PRECOPY = 0,
+    QEMU_VHOST_USER_FS_FEATURE_SEPARATE_OPTIONS,
+    QEMU_VHOST_USER_FS_FEATURE_LAST
+} qemuVhostUserFSFeature;
+
+VIR_ENUM_DECL(qemuVhostUserFSFeature);
diff --git a/src/qemu/qemu_virtiofs.c b/src/qemu/qemu_virtiofs.c
index 78897d8177..aba6a19562 100644
--- a/src/qemu/qemu_virtiofs.c
+++ b/src/qemu/qemu_virtiofs.c
@@ -446,8 +446,13 @@ qemuVirtioFSPrepareDomain(virQEMUDriver *driver,
     if (fs->sock)
         return 0;
 
-    if (!fs->binary && qemuVhostUserFillDomainFS(driver, fs) < 0)
-        return -1;
+    if (fs->binary) {
+        if (qemuVhostUserFillFSCapabilities(&fs->caps, fs->binary, true) < 0)
+            return -1;
+    } else {
+        if (qemuVhostUserFillDomainFS(driver, fs) < 0)
+            return -1;
+    }
 
     if (!driver->privileged && !fs->idmap.uidmap) {
         if (qemuVirtioFSPrepareIdMap(fs) < 0)
-- 
2.45.2