Re: [PATCH v8 1/2] xen+tools: Report Interrupt Controller Virtualization capabilities on x86

From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jane Malalane <jane.malalane@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>, Wei Liu <wl@xen.org>,
	"Anthony PERARD" <anthony.perard@citrix.com>,
	Juergen Gross <jgross@suse.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Jan Beulich <jbeulich@suse.com>, Julien Grall <julien@xen.org>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Bertrand Marquis <bertrand.marquis@arm.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Kevin Tian <kevin.tian@intel.com>
Subject: Re: [PATCH v8 1/2] xen+tools: Report Interrupt Controller Virtualization capabilities on x86
Date: Wed, 23 Mar 2022 12:30:00 +0100	[thread overview]
Message-ID: <YjsEuMBKI4Kp7kDL@Air-de-Roger> (raw)
In-Reply-To: <20220316091315.19281-2-jane.malalane@citrix.com>

On Wed, Mar 16, 2022 at 09:13:14AM +0000, Jane Malalane wrote:
> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
> index e1e1fa14e6..77ce0b2121 100644
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -343,6 +343,15 @@ static int vmx_init_vmcs_config(bool bsp)
>              MSR_IA32_VMX_PROCBASED_CTLS2, &mismatch);
>      }
>  
> +    /* Check whether hardware supports accelerated xapic and x2apic. */
> +    if ( bsp )
> +    {
> +        assisted_xapic_available = cpu_has_vmx_virtualize_apic_accesses;
> +        assisted_x2apic_available = cpu_has_vmx_virtualize_x2apic_mode &&
> +                                    (cpu_has_vmx_apic_reg_virt ||
> +                                     cpu_has_vmx_virtual_intr_delivery);
> +    }

I'm afraid using cpu_has_vmx_* is not correct here. The
vmx_secondary_exec_control variable hasn't been set here, so you will
need to move those checks to the end of the function, after
vmx_secondary_exec_control has been set.

Thanks, Roger.