Re: [libvirt] add ivshmem property master

[Martin Kletzander]

[Please use git send-email or a normal client, this attachment is difficult to
go through, not to mention that the diff is completely broken]

On Fri, Feb 01, 2019 at 08:16:20AM +0000, 吴 雨霖 wrote:

[Problem Description]

 I read qemu-doc.texi in qemu-mster source code, which have a explain of 
migrating ivshmem below

“With device property @option{master=on}, the guest will copy the shared.memory 
on migration to the destination host.  With @option{master=off}, the guest will 
not be able to migrate with the device attached.”

 However, libvirt library can not recognize the property “master=on”. When I 
directly used command "qemu-kvm -device 
ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,master=on,bus=pci.0,addr=0xa” to launch 
a guest, qemu support ivshmem property master=on.

 So, I suggest adding code to support property master=on in libvirt.

QEMU supports that, but libvirt doesn't.  I remember there was a reason
for it, but I can't seem to recall what the particular reason was.

What is the reason for you to need master=on?

[Code Review]



   The below is the part of source code in qemu-master. There's no definition 
here  about ivshmem master.

domain_conf.h

struct _virDomainShmemDef {

   char *name;

   unsigned long long size;

   int model; /* enum virDomainShmemModel */

   struct {

       bool enabled;

       virDomainChrSourceDef chr;

   } server;

   struct {

       bool enabled;

       unsigned vectors;

       virTristateSwitch ioeventfd;

   } msi;

   virDomainDeviceInfo info;

};

[changed code]

src/conf/domain_conf.c

src/conf/domain_conf.h



[Detail of Source Code Modification]


diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 9f75dc4..b41be37 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -14665,7 +14665,6 @@ virDomainShmemDefParseXML(virDomainXMLOptionPtr xmlopt,
    xmlNodePtr save = ctxt->node;
    xmlNodePtr server = NULL;

-
    if (VIR_ALLOC(def) < 0)
        return NULL;

-
    if (VIR_ALLOC(def) < 0)
        return NULL;

@@ -14685,12 +14684,28 @@ virDomainShmemDefParseXML(virDomainXMLOptionPtr 
xmlopt,
        VIR_FREE(tmp);
    }

+
    if (!(def->name = virXMLPropString(node, "name"))) {
        virReportError(VIR_ERR_XML_ERROR, "%s",
                       _("shmem element must contain 'name' attribute"));
        goto cleanup;
    }

+
+       if ((tmp = virXMLPropString(node, "master"))) {
+               int val;
+
+               if ((val = virTristateSwitchTypeFromString(tmp)) <= 0) {
+                       virReportError(VIR_ERR_XML_ERROR,
+                                                  _("invalid ivshmem master setting 
for shmem: '%s'"),
+                                                  tmp);
+                       goto cleanup;
+               }
+               def->master = val;
+               VIR_FREE(tmp);
+       }
+
+
    if (virDomainParseScaledValue("./size[1]", NULL, ctxt,
                                  &def->size, 1, ULLONG_MAX, false) < 0)
        goto cleanup;
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index f1e6e4e..615d721 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1727,8 +1727,10 @@ typedef enum {

struct _virDomainShmemDef {
    char *name;
+
    unsigned long long size;
    int model; /* enum virDomainShmemModel */
+   virTristateSwitch master;
    struct {
        bool enabled;
        virDomainChrSourceDef chr;
}

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