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Re: [Xen-devel] [PATCH v2 2/3] x86 Test and expose CPUID faulting capabilities in /proc/cpuinfo
- To: Kyle Huey <me@xxxxxxxxxxxx>, Robert O'Callahan <robert@xxxxxxxxxxxxx>
- From: David Vrabel <david.vrabel@xxxxxxxxxx>
- Date: Thu, 15 Sep 2016 11:05:02 +0100
- Cc: Juergen Gross <jgross@xxxxxxxx>, Len Brown <len.brown@xxxxxxxxx>, "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, "maintainer:X86 ARCHITECTURE 32-BIT AND 64-BIT" <x86@xxxxxxxxxx>, "open list:X86 ARCHITECTURE 32-BIT AND 64-BIT" <linux-kernel@xxxxxxxxxxxxxxx>, Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>, Huang Rui <ray.huang@xxxxxxx>, Aravind Gopalakrishnan <aravind.gopalakrishnan@xxxxxxx>, David Vrabel <david.vrabel@xxxxxxxxxx>, Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>, "moderated list:XEN HYPERVISOR INTERFACE" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>
- Delivery-date: Thu, 15 Sep 2016 10:05:25 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 14/09/16 22:01, Kyle Huey wrote:
> Xen advertises the underlying support for CPUID faulting but not does pass
> through writes to the relevant MSR, nor does it virtualize it, so it does
> not actually work. For now mask off the relevant bit on MSR_PLATFORM_INFO.
Could you clarify in the commit message that it is PV guests that are
affected.
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1050,6 +1050,9 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err)
> #endif
> val &= ~X2APIC_ENABLE;
> break;
> + case MSR_PLATFORM_INFO:
> + val &= ~CPUID_FAULTING_SUPPORT;
> + break;
> }
> return val;
> }
Acked-by: David Vrabel <david.vrabel@xxxxxxxxxx>
David
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