Re: [Xen-devel] [PATCH v3 2/2] nvmx: always trap accesses to x2APIC MSRs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.02.2020 18:37, Roger Pau Monne wrote:
> @@ -587,6 +588,16 @@ 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.
> +     */
> +    for ( msr = MSR_X2APIC_FIRST; msr <= MSR_X2APIC_FIRST + 0xff; msr++ )
> +    {
> +        __set_bit(msr, msr_bitmap->read_low);
> +        __set_bit(msr, msr_bitmap->write_low);
> +    }

Pull in bitmap_set() (and then also bitmap_clear()) from Linux
for doing this more efficiently?

Jan

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