From 8e53324021645f820a01bf8aa745711c802c8542 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 6 Nov 2020 17:03:12 +0800 Subject: KVM: VMX: Convert vcpu_vmx.exit_reason to a union Convert vcpu_vmx.exit_reason from a u32 to a union (of size u32). The full VM_EXIT_REASON field is comprised of a 16-bit basic exit reason in bits 15:0, and single-bit modifiers in bits 31:16. Historically, KVM has only had to worry about handling the "failed VM-Entry" modifier, which could only be set in very specific flows and required dedicated handling. I.e. manually stripping the FAILED_VMENTRY bit was a somewhat viable approach. But even with only a single bit to worry about, KVM has had several bugs related to comparing a basic exit reason against the full exit reason store in vcpu_vmx. Upcoming Intel features, e.g. SGX, will add new modifier bits that can be set on more or less any VM-Exit, as opposed to the significantly more restricted FAILED_VMENTRY, i.e. correctly handling everything in one-off flows isn't scalable. Tracking exit reason in a union forces code to explicitly choose between consuming the full exit reason and the basic exit, and is a convenient way to document and access the modifiers. No functional change intended. Cc: Xiaoyao Li Signed-off-by: Sean Christopherson Signed-off-by: Chenyi Qiang Message-Id: <20201106090315.18606-2-chenyi.qiang@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.h | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/vmx/vmx.h') diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 9d3a557949ac..4dd71b7494ea 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -70,6 +70,29 @@ struct pt_desc { struct pt_ctx guest; }; +union vmx_exit_reason { + struct { + u32 basic : 16; + u32 reserved16 : 1; + u32 reserved17 : 1; + u32 reserved18 : 1; + u32 reserved19 : 1; + u32 reserved20 : 1; + u32 reserved21 : 1; + u32 reserved22 : 1; + u32 reserved23 : 1; + u32 reserved24 : 1; + u32 reserved25 : 1; + u32 reserved26 : 1; + u32 enclave_mode : 1; + u32 smi_pending_mtf : 1; + u32 smi_from_vmx_root : 1; + u32 reserved30 : 1; + u32 failed_vmentry : 1; + }; + u32 full; +}; + /* * The nested_vmx structure is part of vcpu_vmx, and holds information we need * for correct emulation of VMX (i.e., nested VMX) on this vcpu. @@ -244,7 +267,7 @@ struct vcpu_vmx { int vpid; bool emulation_required; - u32 exit_reason; + union vmx_exit_reason exit_reason; /* Posted interrupt descriptor */ struct pi_desc pi_desc; -- cgit 1.4.1