Wincy Van wrote on 2015-01-24:
> Currently, if L1 enables MSR_BITMAP, we will emulate this feature, all of L2's
> msr access is intercepted by L0. Since many features like virtualize x2apic mode
> has a complicated logic and it is difficult for us to emulate, we should use
> hardware and merge the bitmap.
>
> This patch introduces nested_vmx_merge_msr_bitmap for future use.
>
> Signed-off-by: Wincy Van <fanwenyi0529@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 71
> +++++++++++++++++++++++++++++++++++++++++++--------
> 1 files changed, 60 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index c987374..36d0724
> 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -798,6 +798,7 @@ static unsigned long *vmx_msr_bitmap_legacy;
> static unsigned long *vmx_msr_bitmap_longmode; static unsigned long
> *vmx_msr_bitmap_legacy_x2apic; static unsigned long
> *vmx_msr_bitmap_longmode_x2apic;
> +static unsigned long *vmx_msr_bitmap_nested;
> static unsigned long *vmx_vmread_bitmap; static unsigned long
> *vmx_vmwrite_bitmap;
>
> @@ -5812,13 +5813,18 @@ static __init int hardware_setup(void)
> (unsigned long
> *)__get_free_page(GFP_KERNEL);
> if (!vmx_msr_bitmap_longmode_x2apic)
> goto out4;
> +
> + vmx_msr_bitmap_nested = (unsigned long
> *)__get_free_page(GFP_KERNEL);
> + if (!vmx_msr_bitmap_nested)
> + goto out5;
> +
Since the nested virtualization is off by default. It's better to allocate the page
only when nested is true. Maybe adding the following check is better:
if (nested) {
vmx_msr_bitmap_nested = (unsigned long *)__get_free_page(GFP_KERNEL);
if (!vmx_msr_bitmap_nested)
goto out5;
}
...snip...
> +
> +/*
> + * Merge L0's and L1's MSR bitmap, return false to indicate that
> + * we do not use the hardware.
> + */
> +static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
> + struct vmcs12
> *vmcs12) {
> + return false;
> +}
> +
The following patches have nothing to do with the MSR control. Why leave the function empty here?
Best regards,
Yang
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