>From a discussion last year[1], Dan recommended libvirt drop the tain
flag for cpu host-passthrough, unless the VM has been migrated.

This repurposes the existing host-cpu taint flag to do just that.

[1]: https://www.redhat.com/archives/virt-tools-list/2019-February/msg00041.html

https://bugzilla.redhat.com/show_bug.cgi?id=1673098

Signed-off-by: Cole Robinson <crobinso@redhat.com>
---
 src/conf/domain_conf.h  | 2 +-
 src/qemu/qemu_domain.c  | 7 +++++--
 src/qemu/qemu_domain.h  | 3 ++-
 src/qemu/qemu_process.c | 2 +-
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 9a44315519..450686dfb5 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2736,7 +2736,7 @@ typedef enum {
     VIR_DOMAIN_TAINT_SHELL_SCRIPTS,    /* Network configuration using opaque shell scripts */
     VIR_DOMAIN_TAINT_DISK_PROBING,     /* Relying on potentially unsafe disk format probing */
     VIR_DOMAIN_TAINT_EXTERNAL_LAUNCH,  /* Externally launched guest domain */
-    VIR_DOMAIN_TAINT_HOST_CPU,         /* Host CPU passthrough in use */
+    VIR_DOMAIN_TAINT_HOST_CPU,         /* Host CPU passthrough in use after migration */
     VIR_DOMAIN_TAINT_HOOK,             /* Domain (possibly) changed via hook script */
     VIR_DOMAIN_TAINT_CDROM_PASSTHROUGH,/* CDROM passthrough */
     VIR_DOMAIN_TAINT_CUSTOM_DTB,       /* Custom device tree blob was specified */
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 0331fd55e0..ed4bdbd7fb 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -6115,7 +6115,8 @@ void qemuDomainObjTaint(virQEMUDriverPtr driver,
 
 void qemuDomainObjCheckTaint(virQEMUDriverPtr driver,
                              virDomainObjPtr obj,
-                             qemuDomainLogContextPtr logCtxt)
+                             qemuDomainLogContextPtr logCtxt,
+                             bool incomingMigration)
 {
     size_t i;
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
@@ -6144,7 +6145,9 @@ void qemuDomainObjCheckTaint(virQEMUDriverPtr driver,
                            VIR_DOMAIN_TAINT_CUSTOM_HYPERVISOR_FEATURE, logCtxt);
     }
 
-    if (obj->def->cpu && obj->def->cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH)
+    if (obj->def->cpu &&
+        obj->def->cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH &&
+        incomingMigration)
         qemuDomainObjTaint(driver, obj, VIR_DOMAIN_TAINT_HOST_CPU, logCtxt);
 
     for (i = 0; i < obj->def->ndisks; i++)
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index ec776ced72..9bf32e16c9 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -567,7 +567,8 @@ void qemuDomainObjTaint(virQEMUDriverPtr driver,
 
 void qemuDomainObjCheckTaint(virQEMUDriverPtr driver,
                              virDomainObjPtr obj,
-                             qemuDomainLogContextPtr logCtxt);
+                             qemuDomainLogContextPtr logCtxt,
+                             bool incomingMigration);
 void qemuDomainObjCheckDiskTaint(virQEMUDriverPtr driver,
                                  virDomainObjPtr obj,
                                  virDomainDiskDefPtr disk,
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 9122069cc9..57d764014a 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6856,7 +6856,7 @@ qemuProcessLaunch(virConnectPtr conn,
 
     qemuLogOperation(vm, "starting up", cmd, logCtxt);
 
-    qemuDomainObjCheckTaint(driver, vm, logCtxt);
+    qemuDomainObjCheckTaint(driver, vm, logCtxt, incoming != NULL);
 
     qemuDomainLogContextMarkPosition(logCtxt);
 
-- 
2.28.0

On Sun, Oct 04, 2020 at 03:10:52PM -0400, Cole Robinson wrote:
> From a discussion last year[1], Dan recommended libvirt drop the tain
> flag for cpu host-passthrough, unless the VM has been migrated.
> 
> This repurposes the existing host-cpu taint flag to do just that.
> 
> [1]: https://www.redhat.com/archives/virt-tools-list/2019-February/msg00041.html
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1673098
> 
> Signed-off-by: Cole Robinson <crobinso@redhat.com>
> ---
>  src/conf/domain_conf.h  | 2 +-
>  src/qemu/qemu_domain.c  | 7 +++++--
>  src/qemu/qemu_domain.h  | 3 ++-
>  src/qemu/qemu_process.c | 2 +-
>  4 files changed, 9 insertions(+), 5 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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