From: David Vrabel <david.vrabel@citrix.com>
To: Dave Hansen <dave.hansen@linux.intel.com>,
Kyle Huey <me@kylehuey.com>,
"Robert O'Callahan" <robert@ocallahan.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Borislav Petkov <bp@suse.de>,
"Andy Lutomirski" <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Huang Rui" <ray.huang@amd.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Len Brown <len.brown@intel.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>,
"moderated list:XEN HYPERVISOR INTERFACE"
<xen-devel@lists.xenproject.org>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v2 2/3] x86 Test and expose CPUID faulting capabilities in /proc/cpuinfo
Date: Thu, 15 Sep 2016 11:07:30 +0100 [thread overview]
Message-ID: <57DA72E2.2070408@citrix.com> (raw)
In-Reply-To: <57D9C2AC.8050905@linux.intel.com>
On 14/09/16 22:35, Dave Hansen wrote:
> On 09/14/2016 02:01 PM, 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.
>
> That needs to make it into a comment, please.
>
> That *is* a Xen bug, right?
This is probably fixed in the latest version of Xen. Andrew Cooper
would know for sure.
>> --- 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;
>> }
>
> Does this mean that Xen guests effectively can't take advantage of this
> feature?
PV guests only.
David
next prev parent reply other threads:[~2016-09-15 10:07 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1473886902-17902-1-git-send-email-khuey@kylehuey.com>
2016-09-14 21:01 ` [PATCH v2 1/3] syscalls,x86 Expose arch_prctl on x86-32 Kyle Huey
2016-09-14 21:29 ` Dave Hansen
2016-09-14 21:35 ` Kyle Huey
2016-09-14 21:46 ` Dave Hansen
2016-09-14 21:56 ` Kyle Huey
2016-09-14 22:23 ` kbuild test robot
2016-09-15 0:01 ` kbuild test robot
2016-09-15 0:01 ` kbuild test robot
2016-09-15 1:14 ` Andy Lutomirski
2016-09-14 21:01 ` [PATCH v2 2/3] x86 Test and expose CPUID faulting capabilities in /proc/cpuinfo Kyle Huey
2016-09-14 21:01 ` Kyle Huey
2016-09-14 21:35 ` Dave Hansen
2016-09-14 21:35 ` Dave Hansen
2016-09-14 22:03 ` Kyle Huey
2016-09-15 1:17 ` Andy Lutomirski
2016-09-15 2:20 ` Kyle Huey
2016-09-15 2:20 ` Kyle Huey
2016-09-15 20:38 ` H. Peter Anvin
2016-09-15 20:38 ` H. Peter Anvin
2016-09-15 23:18 ` Andy Lutomirski
2016-09-15 23:18 ` Andy Lutomirski
2016-09-15 1:17 ` Andy Lutomirski
2016-09-14 22:03 ` Kyle Huey
2016-09-15 10:07 ` David Vrabel [this message]
2016-09-15 10:07 ` David Vrabel
2016-09-15 10:05 ` [Xen-devel] " David Vrabel
2016-09-15 10:25 ` Jan Beulich
2016-09-15 10:25 ` [Xen-devel] " Jan Beulich
2016-09-15 19:11 ` Kyle Huey
2016-09-15 19:37 ` Andy Lutomirski
2016-09-15 19:37 ` [Xen-devel] " Andy Lutomirski
2016-09-15 23:36 ` Kyle Huey
2016-09-15 23:36 ` [Xen-devel] " Kyle Huey
2016-09-15 19:41 ` Boris Ostrovsky
2016-09-15 19:41 ` Boris Ostrovsky
2016-09-15 19:11 ` Kyle Huey
2016-09-15 10:05 ` David Vrabel
2016-09-14 21:01 ` [PATCH v2 3/3] x86,arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey
2016-09-15 1:29 ` Andy Lutomirski
2016-09-15 1:47 ` Kyle Huey
2016-09-15 1:54 ` Andy Lutomirski
2016-09-15 2:19 ` Kyle Huey
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