linux-kernel - [PATCH 2/3] KVM: x86: Take an unsigned 32-bit int for has_emulated

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Message-Id: <20200218234012.7110-3-sean.j.christopherson@intel.com>
Date:   Tue, 18 Feb 2020 15:40:11 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: x86: Take an unsigned 32-bit int for has_emulated_msr()'s index

Take a u32 for the index in has_emulated_msr() to match hardware, which
treats MSR indices as unsigned 32-bit values.  Functionally, taking a
signed int doesn't cause problems with the current code base, but could
theoretically cause problems with 32-bit KVM, e.g. if the index were
checked via a less-than statement, which would evaluate incorrectly for
MSR indices with bit 31 set.

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/svm.c              | 2 +-
 arch/x86/kvm/vmx/vmx.c          | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4dffbc10d3f8..cac9c40e505c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1050,7 +1050,7 @@ struct kvm_x86_ops {
 	int (*hardware_setup)(void);               /* __init */
 	void (*hardware_unsetup)(void);            /* __exit */
 	bool (*cpu_has_accelerated_tpr)(void);
-	bool (*has_emulated_msr)(int index);
+	bool (*has_emulated_msr)(u32 index);
 	void (*cpuid_update)(struct kvm_vcpu *vcpu);
 
 	struct kvm *(*vm_alloc)(void);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a3e32d61d60c..2991a4a1fc30 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5989,7 +5989,7 @@ static bool svm_cpu_has_accelerated_tpr(void)
 	return false;
 }
 
-static bool svm_has_emulated_msr(int index)
+static bool svm_has_emulated_msr(u32 index)
 {
 	switch (index) {
 	case MSR_IA32_MCG_EXT_CTL:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9a6664886f2e..47017da35ac4 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6251,7 +6251,7 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu,
 		*exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
 }
 
-static bool vmx_has_emulated_msr(int index)
+static bool vmx_has_emulated_msr(u32 index)
 {
 	switch (index) {
 	case MSR_IA32_SMBASE:
-- 
2.24.1