qemu: Allow cachetune only for KVM domains

[libvirt] [PATCH] qemu: Allow cachetune only for KVM domains

Posted by Michal Privoznik 7 years, 7 months ago

https://bugzilla.redhat.com/show_bug.cgi?id=1541921

In TCG mode, there are no vCPU threads and thus there's nothing
to be placed into resctrl CGroup. Forbid such configuration.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_domain.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index fee44812c1..a39d9a46a0 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3980,6 +3980,13 @@ qemuDomainDefValidate(const virDomainDef *def,
         }
     }
 
+    if (def->ncachetunes &&
+        def->virtType != VIR_DOMAIN_VIRT_KVM) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("cachetune is only supported for KVM domains"));
+        goto cleanup;
+    }
+
     if (qemuDomainDefValidateFeatures(def, qemuCaps) < 0)
         goto cleanup;
 
-- 
2.16.4

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Re: [libvirt] [PATCH] qemu: Allow cachetune only for KVM domains

Posted by Daniel P. Berrangé 7 years, 7 months ago

On Thu, Jun 28, 2018 at 02:45:38PM +0200, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1541921
> 
> In TCG mode, there are no vCPU threads and thus there's nothing
> to be placed into resctrl CGroup. Forbid such configuration.

This reminds me (again) that we need to add MTTCG support to libvirt
which allows one thread per vCPU with TCG.

> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  src/qemu/qemu_domain.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index fee44812c1..a39d9a46a0 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -3980,6 +3980,13 @@ qemuDomainDefValidate(const virDomainDef *def,
>          }
>      }
>  
> +    if (def->ncachetunes &&
> +        def->virtType != VIR_DOMAIN_VIRT_KVM) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                       _("cachetune is only supported for KVM domains"));
> +        goto cleanup;
> +    }
> +
>      if (qemuDomainDefValidateFeatures(def, qemuCaps) < 0)
>          goto cleanup;

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


Regards,
Daniel
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Re: [libvirt] [PATCH] qemu: Allow cachetune only for KVM domains

Posted by Pavel Hrdina 7 years, 7 months ago

On Thu, Jun 28, 2018 at 02:45:38PM +0200, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1541921
> 
> In TCG mode, there are no vCPU threads and thus there's nothing
> to be placed into resctrl CGroup. Forbid such configuration.

Just a small nit, resctrl is not a CGroup.

Pavel
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