Re: [Xen-devel] [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr

[David Vrabel]

On 02/04/16 15:01, Andy Lutomirski wrote:
> This adds paravirt hooks for unsafe MSR access.  On native, they
> call native_{read,write}_msr.  On Xen, they use
> xen_{read,write}_msr_safe.
> 
> Nothing uses them yet for ease of bisection.  The next patch will
> use them in rdmsrl, wrmsrl, etc.
> 
> I intentionally didn't make them warn on #GP on Xen.  I think that
> should be done separately by the Xen maintainers.
...
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c

Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>

> @@ -1092,6 +1092,26 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
>  	return ret;
>  }
>  
> +static u64 xen_read_msr(unsigned int msr)
> +{
> +	/*
> +	 * This will silently swallow a #GP from RDMSR.  It may be worth
> +	 * changing that.

This probably isn't important.

David