Re: [PATCH 2/2] Add MSR Bitmap support in VMX

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

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Avi Kivity wrote:
> However, I do see an issue with my proposal. To get the physical address
> of the page, we need to use vmalloc_to_page(). But that won't work if
> kvm is built into the kernel (and thus uses large pages for data).
>   

Because of this issue, I'd like to apply the patch now and remove the
allocations if/when the module_to_page() thing hits mainline. However:

>  static struct kvm_arch_ops vmx_arch_ops = {
>  	.cpu_has_kvm_support = cpu_has_kvm_support,
>  	.disabled_by_bios = vmx_disabled_by_bios,
> @@ -2505,6 +2523,28 @@ static int __init vmx_init(void)
>  	if (r)
>  		goto out1;
>  
> +	if (cpu_has_vmx_msr_bitmap) {
> +		vmx_msr_bitmap = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
> +		if (!vmx_msr_bitmap) {
> +			r = -ENOMEM;
> +			goto out1;
>   

We need to undo kvm_init_arch() here.

> +		}
> +
> +		printk(KERN_INFO "kvm: Enable MSR bitmap support.\n");
> +
> +		va = kmap(vmx_msr_bitmap);
>   

kmap_atomic() is preferable.

>  
> +#define cpu_has_vmx_msr_bitmap \
> +	(vmcs_config.cpu_based_exec_ctrl & CPU_BASED_USE_MSR_BITMAPS)
> +
>  #endif

This needs to be an inline local to vmx.c.


Did you see any performance improvements out of this?

-- 
error compiling committee.c: too many arguments to function



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