Re: [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests

From: Konrad Rzeszutek Wilk
Date: Mon Sep 21 2015 - 11:30:47 EST


On Mon, Sep 21, 2015 at 09:09:28AM -0400, Boris Ostrovsky wrote:
> For PV guests these registers are set up by hypervisor and thus
> should not be written by the guest. The comment in xen_write_msr_safe()
> says so but we still write the MSRs, causing the hypervisor to
> print a warning.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

> ---
> arch/x86/xen/enlighten.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 30d12af..1f1dbd2 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1077,6 +1077,7 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
> /* Fast syscall setup is all done in hypercalls, so
> these are all ignored. Stub them out here to stop
> Xen console noise. */
> + break;
>
> default:
> if (!pmu_msr_write(msr, low, high, &ret))
> --
> 2.1.0
>
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