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Groups > linux.kernel > #1229303 > unrolled thread

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

Started byBoris Ostrovsky <boris.ostrovsky@oracle.com>
First post2015-09-21 15:20 +0200
Last post2015-09-21 17:40 +0200
Articles 2 — 2 participants

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  [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-09-21 15:20 +0200
    Re: [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV  guests Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2015-09-21 17:40 +0200

#1229303 — [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests

FromBoris Ostrovsky <boris.ostrovsky@oracle.com>
Date2015-09-21 15:20 +0200
Subject[PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests
Message-ID<qb9aH-7Hp-37@gated-at.bofh.it>
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@oracle.com>
---
 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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#1229484 — Re: [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests

FromKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date2015-09-21 17:40 +0200
SubjectRe: [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests
Message-ID<qbbma-2la-19@gated-at.bofh.it>
In reply to#1229303
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@oracle.com>

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

> ---
>  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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