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x86/bugs/multihit: Fix mitigation reporting when VMX is not in use

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On systems that have virtualization disabled or unsupported, sysfs
mitigation for X86_BUG_ITLB_MULTIHIT is reported incorrectly as:

  $ cat /sys/devices/system/cpu/vulnerabilities/itlb_multihit
  KVM: Vulnerable

System is not vulnerable to DoS attack from a rogue guest when
virtualization is disabled or unsupported in the hardware. Change the
mitigation reporting for these cases.

Fixes: b8e8c8303f ("kvm: mmu: ITLB_MULTIHIT mitigation")
Reported-by: Nelson Dsouza <nelson.dsouza@linux.intel.com>
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/0ba029932a816179b9d14a30db38f0f11ef1f166.1594925782.git.pawan.kumar.gupta@linux.intel.com
This commit is contained in:
Pawan Gupta
2020-07-16 12:23:59 -07:00
committed by Ingo Molnar
parent 76d10256a9
commit f29dfa53cc
2 changed files with 11 additions and 1 deletions
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4
Documentation/admin-guide/hw-vuln/multihit.rst
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@@ -80,6 +80,10 @@ The possible values in this file are:
- The processor is not vulnerable.
* - KVM: Mitigation: Split huge pages
- Software changes mitigate this issue.
* - KVM: Mitigation: VMX unsupported
- KVM is not vulnerable because Virtual Machine Extensions (VMX) is not supported.
* - KVM: Mitigation: VMX disabled
- KVM is not vulnerable because Virtual Machine Extensions (VMX) is disabled.
* - KVM: Vulnerable
- The processor is vulnerable, but no mitigation enabled