Re: [Xen-devel] [PATCH v4 3/3] nvmx: always trap accesses to x2APIC MSRs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 04.02.2020 18:34, Roger Pau Monne wrote:
> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -596,6 +596,13 @@ static void update_msrbitmap(struct vcpu *v, uint32_t 
> shadow_ctrl)
>                v->arch.hvm.vmx.msr_bitmap->write_high,
>                sizeof(msr_bitmap->write_high) * 8);
>  
> +    /*
> +     * Nested VMX doesn't support any x2APIC hardware virtualization, so
> +     * make sure all the x2APIC MSRs are trapped.
> +     */
> +    bitmap_set(msr_bitmap->read_low, MSR_X2APIC_FIRST, 0xff);
> +    bitmap_set(msr_bitmap->write_low, MSR_X2APIC_FIRST, 0xff);

If you decide to address the Arm issue with these functions,
and hence don't go back to the v3 variant, then the last
arguments here need to be 0x100 afaict.

Jan

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