From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
Sean Christopherson <seanjc@google.com>,
x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
"H. Peter Anvin" <hpa@zytor.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Jim Mattson <jmattson@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Ingo Molnar <mingo@redhat.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 3/3] KVM: SVM: add module param to control the #SMI interception
Date: Wed, 7 Jul 2021 15:51:00 +0300 [thread overview]
Message-ID: <20210707125100.677203-4-mlevitsk@redhat.com> (raw)
In-Reply-To: <20210707125100.677203-1-mlevitsk@redhat.com>
In theory there are no side effects of not intercepting #SMI,
because then #SMI becomes transparent to the OS and the KVM.
Plus an observation on recent Zen2 CPUs reveals that these
CPUs ignore #SMI interception and never deliver #SMI VMexits.
This is also useful to test nested KVM to see that L1
handles #SMIs correctly in case when L1 doesn't intercept #SMI.
Finally the default remains the same, the SMI are intercepted
by default thus this patch doesn't have any effect unless
non default module param value is used.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/nested.c | 4 ++++
arch/x86/kvm/svm/svm.c | 10 +++++++++-
arch/x86/kvm/svm/svm.h | 1 +
3 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 21d03e3a5dfd..2884c54a72bb 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -154,6 +154,10 @@ void recalc_intercepts(struct vcpu_svm *svm)
for (i = 0; i < MAX_INTERCEPT; i++)
c->intercepts[i] |= g->intercepts[i];
+
+ /* If SMI is not intercepted, ignore guest SMI intercept as well */
+ if (!intercept_smi)
+ vmcb_clr_intercept(c, INTERCEPT_SMI);
}
static void copy_vmcb_control_area(struct vmcb_control_area *dst,
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index a3aad97fa427..9f95e77d5ce1 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -198,6 +198,11 @@ module_param(avic, bool, 0444);
bool __read_mostly dump_invalid_vmcb;
module_param(dump_invalid_vmcb, bool, 0644);
+
+bool intercept_smi = true;
+module_param(intercept_smi, bool, 0444);
+
+
static bool svm_gp_erratum_intercept = true;
static u8 rsm_ins_bytes[] = "\x0f\xaa";
@@ -1206,7 +1211,10 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
svm_set_intercept(svm, INTERCEPT_INTR);
svm_set_intercept(svm, INTERCEPT_NMI);
- svm_set_intercept(svm, INTERCEPT_SMI);
+
+ if (intercept_smi)
+ svm_set_intercept(svm, INTERCEPT_SMI);
+
svm_set_intercept(svm, INTERCEPT_SELECTIVE_CR0);
svm_set_intercept(svm, INTERCEPT_RDPMC);
svm_set_intercept(svm, INTERCEPT_CPUID);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index f89b623bb591..8cb3bd59c5ea 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -31,6 +31,7 @@
#define MSRPM_OFFSETS 16
extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
extern bool npt_enabled;
+extern bool intercept_smi;
/*
* Clean bits in VMCB.
--
2.26.3
next prev parent reply other threads:[~2021-07-07 12:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-07 12:50 [PATCH 0/3] KVM: SMM fixes Maxim Levitsky
2021-07-07 12:50 ` [PATCH 1/3] KVM: SVM: #SMI interception must not skip the instruction Maxim Levitsky
2021-07-07 12:50 ` [PATCH 2/3] KVM: SVM: remove INIT intercept handler Maxim Levitsky
2021-07-07 12:51 ` Maxim Levitsky [this message]
2021-07-08 17:24 ` [PATCH 0/3] KVM: SMM fixes Paolo Bonzini
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