linux-kernel - [PATCH 9/9] KVM: x86: Disable KVM_INTEL_PROVE

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Message-ID: <20240518000430.1118488-10-seanjc@google.com>
Date: Fri, 17 May 2024 17:04:30 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 9/9] KVM: x86: Disable KVM_INTEL_PROVE_VE by default

Disable KVM's "prove #VE" support by default, as it provides no functional
value, and even its sanity checking benefits are relatively limited.  I.e.
it should be fully opt-in even on debug kernels, especially since EPT
Violation #VE suppression appears to be buggy on some CPUs.

Opportunistically add a line in the help text to make it abundantly clear
that KVM_INTEL_PROVE_VE should never be enabled in a production
environment.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/Kconfig | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 2a7f69abcac3..3468efc4be55 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -97,15 +97,15 @@ config KVM_INTEL
 
 config KVM_INTEL_PROVE_VE
         bool "Check that guests do not receive #VE exceptions"
-        default KVM_PROVE_MMU || DEBUG_KERNEL
-        depends on KVM_INTEL
+        depends on KVM_INTEL && DEBUG_KERNEL && EXPERT
         help
-
           Checks that KVM's page table management code will not incorrectly
           let guests receive a virtualization exception.  Virtualization
           exceptions will be trapped by the hypervisor rather than injected
           in the guest.
 
+          This should never be enabled in a production environment.
+
           If unsure, say N.
 
 config X86_SGX_KVM
-- 
2.45.0.215.g3402c0e53f-goog