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Re: [PATCH v5] x86: make Viridian support optional
- To: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 8 Oct 2025 18:04:30 +0200
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- Cc: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Paul Durrant <paul@xxxxxxx>, Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 08 Oct 2025 16:04:41 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 30.09.2025 14:52, Grygorii Strashko wrote:
> --- a/xen/arch/x86/hvm/Kconfig
> +++ b/xen/arch/x86/hvm/Kconfig
> @@ -62,6 +62,16 @@ config ALTP2M
>
> If unsure, stay with defaults.
>
> +config VIRIDIAN
> + bool "Hyper-V enlightenments for guests" if EXPERT
> + default y
> + help
> + Support optimizations for Hyper-V guests such as faster hypercalls,
> + efficient timer and interrupt handling, and enhanced paravirtualized
> + I/O. This is to improve performance and compatibility of Windows VMs.
What is "paravirtualized I/O" about in this context?
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -701,9 +701,12 @@ int hvm_domain_initialise(struct domain *d,
> if ( hvm_tsc_scaling_supported )
> d->arch.hvm.tsc_scaling_ratio = hvm_default_tsc_scaling_ratio;
>
> - rc = viridian_domain_init(d);
> - if ( rc )
> - goto fail2;
> + if ( is_viridian_domain(d) )
> + {
> + rc = viridian_domain_init(d);
> + if ( rc )
> + goto fail2;
> + }
While this looks okay to me, ...
> @@ -739,7 +742,8 @@ void hvm_domain_relinquish_resources(struct domain *d)
> if ( hvm_funcs.nhvm_domain_relinquish_resources )
> alternative_vcall(hvm_funcs.nhvm_domain_relinquish_resources, d);
>
> - viridian_domain_deinit(d);
> + if ( is_viridian_domain(d) )
> + viridian_domain_deinit(d);
... I wonder if viridian_{domain,vcpu}_deinit() better wouldn't be tolerant
to be called anyway, thus avoiding the need for conditionals here and below
(and perhaps being a little more robust overall). Thoughts?
Jan
|
