linux-kernel - [PATCH v2 8/9] KVM: x86: add force_intercept_exceptions

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Message-Id: <20210401135451.1004564-9-mlevitsk@redhat.com>
Date:   Thu,  1 Apr 2021 16:54:50 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Ingo Molnar <mingo@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org (open list),
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Jonathan Corbet <corbet@....net>, Jessica Yu <jeyu@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Will Deacon <will@...nel.org>,
        kvmarm@...ts.cs.columbia.edu (open list:KERNEL VIRTUAL MACHINE FOR
        ARM64 (KVM/arm64)), Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Joerg Roedel <joro@...tes.org>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Jim Mattson <jmattson@...gle.com>,
        Cornelia Huck <cohuck@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-s390@...r.kernel.org (open list:S390),
        Heiko Carstens <hca@...ux.ibm.com>,
        Kieran Bingham <kbingham@...nel.org>,
        linux-doc@...r.kernel.org (open list:DOCUMENTATION),
        linux-arm-kernel@...ts.infradead.org (moderated list:KERNEL VIRTUAL
        MACHINE FOR ARM64 (KVM/arm64)), James Morse <james.morse@....com>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH v2 8/9] KVM: x86: add force_intercept_exceptions_mask

This parameter will be used by VMX and SVM code to force
interception of a set of exceptions, given by a bitmask
for guest debug and/or kvm debug.

This option is not intended for production.

This is based on an idea first shown here:
https://patchwork.kernel.org/project/kvm/patch/20160301192822.GD22677@pd.tnic/

CC: Borislav Petkov <bp@...e.de>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/x86.c | 3 +++
 arch/x86/kvm/x86.h | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3627ce8fe5bb..1a51031d64d8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -176,6 +176,9 @@ module_param(force_emulation_prefix, bool, S_IRUGO);
 int __read_mostly pi_inject_timer = -1;
 module_param(pi_inject_timer, bint, S_IRUGO | S_IWUSR);
 
+uint force_intercept_exceptions_mask;
+module_param(force_intercept_exceptions_mask, uint, S_IRUGO | S_IWUSR);
+EXPORT_SYMBOL_GPL(force_intercept_exceptions_mask);
 /*
  * Restoring the host value for MSRs that are only consumed when running in
  * usermode, e.g. SYSCALL MSRs and TSC_AUX, can be deferred until the CPU
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index daccf20fbcd5..644480711ff7 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -311,6 +311,8 @@ extern struct static_key kvm_no_apic_vcpu;
 
 extern bool report_ignored_msrs;
 
+extern uint force_intercept_exceptions_mask;
+
 static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
 {
 	return pvclock_scale_delta(nsec, vcpu->arch.virtual_tsc_mult,
-- 
2.26.2