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Re: [PATCH v2 2/2] x86/xen: Allow per-domain usage of hardware virtualized APIC
- To: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Jane Malalane <jane.malalane@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 14 Feb 2022 15:29:14 +0100
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- Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Christian Lindig <christian.lindig@xxxxxxxxxx>, David Scott <dave@xxxxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Mon, 14 Feb 2022 14:29:23 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 08.02.2022 17:17, Roger Pau Monné wrote:
> On Mon, Feb 07, 2022 at 06:21:01PM +0000, Jane Malalane wrote:
>> --- a/xen/arch/x86/traps.c
>> +++ b/xen/arch/x86/traps.c
>> @@ -1115,7 +1115,8 @@ void cpuid_hypervisor_leaves(const struct vcpu *v,
>> uint32_t leaf,
>> if ( !is_hvm_domain(d) || subleaf != 0 )
>> break;
>>
>> - if ( cpu_has_vmx_apic_reg_virt )
>> + if ( cpu_has_vmx_apic_reg_virt &&
>
> You can drop the cpu_has_vmx_apic_reg_virt check here, if
> cpu_has_vmx_apic_reg_virt is false assisted_xapic won't be set to true.
Along these lines ...
>> + v->domain->arch.hvm.assisted_xapic )
>> res->a |= XEN_HVM_CPUID_APIC_ACCESS_VIRT;
>>
>> /*
>> @@ -1124,9 +1125,8 @@ void cpuid_hypervisor_leaves(const struct vcpu *v,
>> uint32_t leaf,
>> * and wrmsr in the guest will run without VMEXITs (see
>> * vmx_vlapic_msr_changed()).
>> */
>> - if ( cpu_has_vmx_virtualize_x2apic_mode &&
>> - cpu_has_vmx_apic_reg_virt &&
>> - cpu_has_vmx_virtual_intr_delivery )
>> + if ( (cpu_has_vmx_apic_reg_virt &&
>> cpu_has_vmx_virtual_intr_delivery) &&
> ^ unneeded parentheses
... this also wants simplifying to just v->domain->arch.hvm.assisted_x2apic:
The apparently stray parentheses were, I think, added in reply to me pointing
out that the check here isn't in line with that put in place by patch 1 in
vmx_init_vmcs_config(). I.e. the inner && really was meant to be || as it
looks. Yet once the two are in line, the same simplification as above is
possible.
Jan
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