From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 16/26] KVM: x86: Add Kconfig-controlled auditing of reverse CPUID lookups
Date: Wed, 29 Jan 2020 15:46:30 -0800 [thread overview]
Message-ID: <20200129234640.8147-17-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200129234640.8147-1-sean.j.christopherson@intel.com>
Add WARNs in the low level __cpuid_entry_get_reg() to assert that the
function and index of the CPUID entry and reverse CPUID entry match.
Wrap the WARNs in a new Kconfig, KVM_CPUID_AUDIT, as the checks add
almost no value in a production environment, i.e. will only detect
blatant KVM bugs and fatal hardware errors. Add a Kconfig instead of
simply wrapping the WARNs with an off-by-default #ifdef so that syzbot
and other automated testing can enable the auditing.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/Kconfig | 10 ++++++++++
arch/x86/kvm/cpuid.h | 5 +++++
2 files changed, 15 insertions(+)
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 840e12583b85..bbbc3258358e 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -96,6 +96,16 @@ config KVM_MMU_AUDIT
This option adds a R/W kVM module parameter 'mmu_audit', which allows
auditing of KVM MMU events at runtime.
+config KVM_CPUID_AUDIT
+ bool "Audit KVM reverse CPUID lookups"
+ depends on KVM
+ help
+ This option enables runtime checking of reverse CPUID lookups in KVM
+ to verify the function and index of the referenced X86_FEATURE_* match
+ the function and index of the CPUID entry being accessed.
+
+ If unsure, say N.
+
# OK, it's a little counter-intuitive to do this, but it puts it neatly under
# the virtualization menu.
source "drivers/vhost/Kconfig"
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 51f19eade5a0..41ff94a7d3e0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -98,6 +98,11 @@ static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature)
static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
const struct cpuid_reg *cpuid)
{
+#ifdef CONFIG_KVM_CPUID_AUDIT
+ WARN_ON_ONCE(entry->function != cpuid->function);
+ WARN_ON_ONCE(entry->index != cpuid->index);
+#endif
+
switch (cpuid->reg) {
case CPUID_EAX:
return &entry->eax;
--
2.24.1
next prev parent reply other threads:[~2020-01-29 23:47 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 23:46 [PATCH 00/26] KVM: x86: Purge kvm_x86_ops->*_supported() Sean Christopherson
2020-01-29 23:46 ` [PATCH 01/26] KVM: x86: Remove superfluous brackets from case statement Sean Christopherson
2020-02-05 14:29 ` Vitaly Kuznetsov
2020-02-05 14:32 ` Sean Christopherson
2020-01-29 23:46 ` [PATCH 02/26] KVM: x86: Take an unsigned 32-bit int for has_emulated_msr()'s index Sean Christopherson
2020-02-05 14:30 ` Vitaly Kuznetsov
2020-01-29 23:46 ` [PATCH 03/26] KVM: x86: Snapshot MSR index in a local variable when processing lists Sean Christopherson
2020-02-05 14:31 ` Vitaly Kuznetsov
2020-01-29 23:46 ` [PATCH 04/26] KVM: x86: Add a kvm_x86_ops hook to query virtualized MSR support Sean Christopherson
2020-02-05 14:34 ` Vitaly Kuznetsov
2020-02-05 14:59 ` Sean Christopherson
2020-02-05 15:22 ` Vitaly Kuznetsov
2020-02-05 15:35 ` Sean Christopherson
2020-02-05 16:55 ` Vitaly Kuznetsov
2020-02-05 17:02 ` Sean Christopherson
2020-02-06 12:08 ` Vitaly Kuznetsov
2020-01-29 23:46 ` [PATCH 05/26] KVM: x86: Move MSR_TSC_AUX existence checks into vendor code Sean Christopherson
2020-02-05 14:39 ` Vitaly Kuznetsov
2020-01-29 23:46 ` [PATCH 06/26] KVM: x86: Move MSR_IA32_BNDCFGS " Sean Christopherson
2020-02-05 14:53 ` Vitaly Kuznetsov
2020-01-29 23:46 ` [PATCH 07/26] KVM: VMX: Add helpers to query Intel PT mode Sean Christopherson
2020-01-29 23:46 ` [PATCH 08/26] KVM: x86: Move RTIT (Intel PT) MSR existence checks into vendor code Sean Christopherson
2020-01-29 23:46 ` [PATCH 09/26] KVM: x86: Calculate the supported xcr0 mask at load time Sean Christopherson
2020-01-29 23:46 ` [PATCH 10/26] KVM: x86: Use supported_xcr0 to detect MPX support Sean Christopherson
2020-01-29 23:46 ` [PATCH 11/26] KVM: x86: Make kvm_mpx_supported() an inline function Sean Christopherson
2020-01-29 23:46 ` [PATCH 12/26] KVM: x86: Drop explicit @func param from ->set_supported_cpuid() Sean Christopherson
2020-01-29 23:46 ` [PATCH 13/26] KVM: x86: Use u32 for holding CPUID register value in helpers Sean Christopherson
2020-01-29 23:46 ` [PATCH 14/26] KVM: x86: Introduce cpuid_entry_{get,has}() accessors Sean Christopherson
2020-01-29 23:46 ` [PATCH 15/26] KVM: x86: Introduce cpuid_entry_{change,set,clear}() mutators Sean Christopherson
2020-01-29 23:46 ` Sean Christopherson [this message]
2020-01-29 23:46 ` [PATCH 17/26] KVM: x86: Handle MPX CPUID adjustment in vendor code Sean Christopherson
2020-01-29 23:46 ` [PATCH 18/26] KVM: x86: Handle INVPCID " Sean Christopherson
2020-01-29 23:46 ` [PATCH 19/26] KVM: x86: Handle UMIP emulation CPUID adjustment in VMX code Sean Christopherson
2020-01-29 23:46 ` [PATCH 20/26] KVM: x86: Handle PKU CPUID adjustment in SVM code Sean Christopherson
2020-01-29 23:46 ` [PATCH 21/26] KVM: x86: Handle RDTSCP CPUID adjustment in VMX code Sean Christopherson
2020-01-29 23:46 ` [PATCH 22/26] KVM: x86: Handle XSAVES " Sean Christopherson
2020-01-29 23:46 ` [PATCH 23/26] KVM: x86: Handle Intel PT CPUID adjustment in vendor code Sean Christopherson
2020-01-29 23:46 ` [PATCH 24/26] KVM: x86: Clear output regs for CPUID 0x14 if PT isn't exposed to guest Sean Christopherson
2020-01-29 23:46 ` [PATCH 25/26] KVM: x86: Handle main Intel PT CPUID leaf in vendor code Sean Christopherson
2020-01-30 0:38 ` Sean Christopherson
2020-01-29 23:46 ` [PATCH 26/26] KVM: VMX: Directly query Intel PT mode when refreshing PMUs Sean Christopherson
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