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Subject[PATCH 2/3] KVM: VMX: return early if msr_bitmap is not supported
Date
The vmx_msr_filter_changed() may directly/indirectly calls only
vmx_enable_intercept_for_msr() or vmx_disable_intercept_for_msr(). Those
two functions may exit immediately if !cpu_has_vmx_msr_bitmap().

vmx_msr_filter_changed()
-> vmx_disable_intercept_for_msr()
-> pt_update_intercept_for_msr()
-> vmx_set_intercept_for_msr()
-> vmx_enable_intercept_for_msr()
-> vmx_disable_intercept_for_msr()

Therefore, we exit early if !cpu_has_vmx_msr_bitmap().

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
arch/x86/kvm/vmx/vmx.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 05319b74bd3d..5a866d3c2bc8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4127,6 +4127,9 @@ static void vmx_msr_filter_changed(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 i;

+ if (!cpu_has_vmx_msr_bitmap())
+ return;
+
/*
* Redo intercept permissions for MSRs that KVM is passing through to
* the guest. Disabling interception will check the new MSR filter and
--
2.34.1

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