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From: "tip-bot for K. Y. Srinivasan" <kys@microsoft.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org,
	kys@microsoft.com, tglx@linutronix.de, hpa@linux.intel.com
Subject: [tip:x86/hyperv] X86: Add a check to catch Xen emulation of Hyper-V
Date: Tue, 12 Feb 2013 16:57:16 -0800	[thread overview]
Message-ID: <tip-db34bbb767bdfa1ebed7214b876fe01c5b7ee457@git.kernel.org> (raw)
In-Reply-To: <1359940959-32168-2-git-send-email-kys@microsoft.com>

Commit-ID:  db34bbb767bdfa1ebed7214b876fe01c5b7ee457
Gitweb:     http://git.kernel.org/tip/db34bbb767bdfa1ebed7214b876fe01c5b7ee457
Author:     K. Y. Srinivasan <kys@microsoft.com>
AuthorDate: Sun, 3 Feb 2013 17:22:38 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Tue, 12 Feb 2013 16:27:03 -0800

X86: Add a check to catch Xen emulation of Hyper-V

Xen emulates Hyper-V to host enlightened Windows. Looks like this
emulation may be turned on by default even for Linux guests. Check and
fail Hyper-V detection if we are on Xen.

[ hpa: the problem here is that Xen doesn't emulate Hyper-V well
  enough, and if the Xen support isn't compiled in, we end up stubling
  over the Hyper-V emulation and try to activate it -- and it fails. ]

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1359940959-32168-2-git-send-email-kys@microsoft.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 646d192..4dab317 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -30,6 +30,13 @@ static bool __init ms_hyperv_platform(void)
 	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 		return false;
 
+	/*
+	 * Xen emulates Hyper-V to support enlightened Windows.
+	 * Check to see first if we are on a Xen Hypervisor.
+	 */
+	if (xen_cpuid_base())
+		return false;
+
 	cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
 	      &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
 

  reply	other threads:[~2013-02-13  0:58 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-04  1:21 [PATCH 0/3] X86: Deliver Hyper-V interrupts on a seperate IDT vector K. Y. Srinivasan
2013-02-04  1:22 ` [PATCH 1/3] x86: Hyper-V: register clocksource only if its advertised K. Y. Srinivasan
2013-02-04  1:22   ` [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V K. Y. Srinivasan
2013-02-13  0:57     ` tip-bot for K. Y. Srinivasan [this message]
2013-04-17  7:06     ` Michael S. Tsirkin
2013-04-17  9:10       ` KVM "Hyper-V emulation" -- this can be related "Linux on Hyper-V" ? Or "KVM emulates Hyper-V" as "Hyper-V emulates Hyper-V" ? " Victor Miasnikov
2013-04-17 10:16         ` Michael S. Tsirkin
2013-04-17 12:12           ` Jan Beulich
2013-04-17 12:15             ` Michael S. Tsirkin
     [not found]             ` <CAP2xkNqGgbYz1gdS85xjA8gwROGY89fAsiaRiGSE90xnzjJ4Xw@mail.gmail.com>
2013-04-17 12:43               ` Michael S. Tsirkin
2013-04-17 14:08                 ` Victor Miasnikov
2013-04-17 13:20       ` KY Srinivasan
2013-04-17 12:48         ` Michael S. Tsirkin
2013-04-17 14:12           ` KY Srinivasan
2013-04-17 13:25             ` Michael S. Tsirkin
2013-04-17 14:34               ` KY Srinivasan
2013-04-17 13:48                 ` Michael S. Tsirkin
2013-04-17 15:31                   ` KY Srinivasan
2013-04-17 15:50                     ` Jan Beulich
2013-04-17 16:28                       ` KY Srinivasan
2013-04-18  7:48                         ` Michael S. Tsirkin
2013-04-18 13:23                           ` KY Srinivasan
2013-04-18 13:30                             ` KY Srinivasan
2013-04-17 13:52         ` Jan Beulich
2013-04-17 13:01           ` Michael S. Tsirkin
2013-04-17 13:11             ` Michael S. Tsirkin
2013-04-17 14:09             ` Jan Beulich
2013-04-17 15:17               ` H. Peter Anvin
2013-02-04  1:22   ` [PATCH 3/3] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts K. Y. Srinivasan
2013-02-13  0:58     ` [tip:x86/hyperv] " tip-bot for K. Y. Srinivasan
2013-02-13  1:58       ` [tip:x86/hyperv] x86, hyperv: HYPERV depends on X86_LOCAL_APIC tip-bot for H. Peter Anvin
2013-02-13  2:05         ` KY Srinivasan
2013-02-13  2:56       ` [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts Yinghai Lu
2013-02-13  3:32         ` KY Srinivasan
2013-02-13  3:46           ` H. Peter Anvin
2013-02-13  3:49             ` KY Srinivasan
2013-02-13  3:54               ` H. Peter Anvin
2013-02-13  3:58                 ` KY Srinivasan
2013-02-13  4:42                   ` Yinghai Lu
2013-02-13 12:47                     ` KY Srinivasan
2013-02-13  0:56   ` [tip:x86/hyperv] x86: Hyper-V: register clocksource only if its advertised tip-bot for Olaf Hering
2013-02-05 11:16 ` [PATCH 0/3] X86: Deliver Hyper-V interrupts on a seperate IDT vector KY Srinivasan

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