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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/virtual/kvm/cpuid.txt
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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+KVM CPUID bits
+Glauber Costa <glommer@redhat.com>, Red Hat Inc, 2010
+=====================================================
+
+A guest running on a kvm host, can check some of its features using
+cpuid. This is not always guaranteed to work, since userspace can
+mask-out some, or even all KVM-related cpuid features before launching
+a guest.
+
+KVM cpuid functions are:
+
+function: KVM_CPUID_SIGNATURE (0x40000000)
+returns : eax = 0x40000001,
+ ebx = 0x4b4d564b,
+ ecx = 0x564b4d56,
+ edx = 0x4d.
+Note that this value in ebx, ecx and edx corresponds to the string "KVMKVMKVM".
+The value in eax corresponds to the maximum cpuid function present in this leaf,
+and will be updated if more functions are added in the future.
+Note also that old hosts set eax value to 0x0. This should
+be interpreted as if the value was 0x40000001.
+This function queries the presence of KVM cpuid leafs.
+
+
+function: define KVM_CPUID_FEATURES (0x40000001)
+returns : ebx, ecx, edx = 0
+ eax = and OR'ed group of (1 << flag), where each flags is:
+
+
+flag || value || meaning
+=============================================================================
+KVM_FEATURE_CLOCKSOURCE || 0 || kvmclock available at msrs
+ || || 0x11 and 0x12.
+------------------------------------------------------------------------------
+KVM_FEATURE_NOP_IO_DELAY || 1 || not necessary to perform delays
+ || || on PIO operations.
+------------------------------------------------------------------------------
+KVM_FEATURE_MMU_OP || 2 || deprecated.
+------------------------------------------------------------------------------
+KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs
+ || || 0x4b564d00 and 0x4b564d01
+------------------------------------------------------------------------------
+KVM_FEATURE_ASYNC_PF || 4 || async pf can be enabled by
+ || || writing to msr 0x4b564d02
+------------------------------------------------------------------------------
+KVM_FEATURE_STEAL_TIME || 5 || steal time can be enabled by
+ || || writing to msr 0x4b564d03.
+------------------------------------------------------------------------------
+KVM_FEATURE_PV_EOI || 6 || paravirtualized end of interrupt
+ || || handler can be enabled by writing
+ || || to msr 0x4b564d04.
+------------------------------------------------------------------------------
+KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
+ || || before enabling paravirtualized
+ || || spinlock support.
+------------------------------------------------------------------------------
+KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
+ || || per-cpu warps are expected in
+ || || kvmclock.
+------------------------------------------------------------------------------