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Bae" To: pbonzini@redhat.com, seanjc@google.com Cc: kvm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, chang.seok.bae@intel.com Subject: [PATCH v5 05/20] KVM: VMX: Refactor instruction information decoding Date: Mon, 20 Jul 2026 17:19:34 +0000 Message-ID: <20260720171949.498680-6-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260720171949.498680-1-chang.seok.bae@intel.com> References: <20260720171949.498680-1-chang.seok.bae@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit KVM currently decodes the VMX instruction information field using a mix of open-coded bit manipulations and ad hoc helpers. Convert all decoding to use helpers to centralize the decoding logic for the transition to a wider instruction information. No functional change intended. Signed-off-by: Chang S. Bae --- V4 -> V5: Fix handle_vmread() first accesses reg2 (0-day). --- arch/x86/kvm/vmx/nested.c | 58 +++++++++++++++++++-------------------- arch/x86/kvm/vmx/vmx.c | 9 +++--- arch/x86/kvm/vmx/vmx.h | 48 +++++++++++++++++++++++++++++--- 3 files changed, 77 insertions(+), 38 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 92b530baa0ee..fdec041e95c7 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5234,7 +5234,7 @@ static void nested_vmx_triple_fault(struct kvm_vcpu *vcpu) * #UD, #GP, or #SS. */ int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification, - u64 vmx_instruction_info, bool wr, int len, gva_t *ret) + u64 instr_info, bool wr, int len, gva_t *ret) { gva_t off; bool exn; @@ -5242,20 +5242,20 @@ int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification, /* * According to Vol. 3B, "Information for VM Exits Due to Instruction - * Execution", on an exit, vmx_instruction_info holds most of the - * addressing components of the operand. Only the displacement part - * is put in exit_qualification (see 3B, "Basic VM-Exit Information"). + * Execution", on an exit, instr_info holds most of the addressing + * components of the operand. Only the displacement part is put in + * exit_qualification (see 3B, "Basic VM-Exit Information"). * For how an actual address is calculated from all these components, * refer to Vol. 1, "Operand Addressing". */ - int scaling = vmx_instruction_info & 3; - int addr_size = (vmx_instruction_info >> 7) & 7; - bool is_reg = vmx_instruction_info & (1u << 10); - int seg_reg = (vmx_instruction_info >> 15) & 7; - int index_reg = (vmx_instruction_info >> 18) & 0xf; - bool index_is_valid = !(vmx_instruction_info & (1u << 22)); - int base_reg = (vmx_instruction_info >> 23) & 0xf; - bool base_is_valid = !(vmx_instruction_info & (1u << 27)); + int scaling = vmx_get_instr_info_scaling(instr_info); + int addr_size = vmx_get_instr_info_addr_size(instr_info); + bool is_reg = vmx_get_instr_info_is_reg(instr_info); + int seg_reg = vmx_get_instr_info_seg_reg(instr_info); + int index_reg = vmx_get_instr_info_index_reg(instr_info); + bool index_is_valid = vmx_get_instr_info_index_is_valid(instr_info); + int base_reg = vmx_get_instr_info_base_reg(instr_info); + bool base_is_valid = vmx_get_instr_info_base_is_valid(instr_info); if (is_reg) { kvm_queue_exception(vcpu, UD_VECTOR); @@ -5664,7 +5664,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) return 1; /* Decode instruction info and find the field to read */ - field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf)); + field = kvm_register_read(vcpu, vmx_get_instr_info_reg2(instr_info)); if (!nested_vmx_is_evmptr12_valid(vmx)) { /* @@ -5712,8 +5712,8 @@ static int handle_vmread(struct kvm_vcpu *vcpu) * Note that the number of bits actually copied is 32 or 64 depending * on the guest's mode (32 or 64 bit), not on the given field's length. */ - if (instr_info & BIT(10)) { - kvm_register_write(vcpu, (((instr_info) >> 3) & 0xf), value); + if (vmx_get_instr_info_is_reg(instr_info)) { + kvm_register_write(vcpu, vmx_get_instr_info_reg(instr_info), value); } else { len = is_64_bit_mode(vcpu) ? 8 : 4; if (get_vmx_mem_address(vcpu, exit_qualification, @@ -5786,8 +5786,8 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu) get_vmcs12(vcpu)->vmcs_link_pointer == INVALID_GPA)) return nested_vmx_failInvalid(vcpu); - if (instr_info & BIT(10)) - value = kvm_register_read(vcpu, (((instr_info) >> 3) & 0xf)); + if (vmx_get_instr_info_is_reg(instr_info)) + value = kvm_register_read(vcpu, vmx_get_instr_info_reg(instr_info)); else { len = is_64_bit_mode(vcpu) ? 8 : 4; if (get_vmx_mem_address(vcpu, exit_qualification, @@ -5798,7 +5798,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu) return kvm_handle_memory_failure(vcpu, r, &e); } - field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf)); + field = kvm_register_read(vcpu, vmx_get_instr_info_reg2(instr_info)); offset = get_vmcs12_field_offset(field); if (offset < 0) @@ -5975,7 +5975,7 @@ static int handle_invept(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); unsigned long type, roots_to_free; - u64 vmx_instruction_info; + u64 instr_info; struct kvm_mmu *mmu; gva_t gva; struct x86_exception e; @@ -5995,8 +5995,8 @@ static int handle_invept(struct kvm_vcpu *vcpu) if (!nested_vmx_check_permission(vcpu)) return 1; - vmx_instruction_info = vmx_get_instr_info(); - gpr_index = vmx_get_instr_info_reg2(vmx_instruction_info); + instr_info = vmx_get_instr_info(); + gpr_index = vmx_get_instr_info_reg2(instr_info); type = kvm_register_read(vcpu, gpr_index); types = (vmx->nested.msrs.ept_caps >> VMX_EPT_EXTENT_SHIFT) & 6; @@ -6008,7 +6008,7 @@ static int handle_invept(struct kvm_vcpu *vcpu) * operand is read even if it isn't needed (e.g., for type==global) */ if (get_vmx_mem_address(vcpu, vmx_get_exit_qual(vcpu), - vmx_instruction_info, false, sizeof(operand), &gva)) + instr_info, false, sizeof(operand), &gva)) return 1; r = kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e); if (r != X86EMUL_CONTINUE) @@ -6055,8 +6055,8 @@ static int handle_invept(struct kvm_vcpu *vcpu) static int handle_invvpid(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); - u64 vmx_instruction_info; unsigned long type, types; + u64 instr_info; gva_t gva; struct x86_exception e; struct { @@ -6076,8 +6076,8 @@ static int handle_invvpid(struct kvm_vcpu *vcpu) if (!nested_vmx_check_permission(vcpu)) return 1; - vmx_instruction_info = vmx_get_instr_info(); - gpr_index = vmx_get_instr_info_reg2(vmx_instruction_info); + instr_info = vmx_get_instr_info(); + gpr_index = vmx_get_instr_info_reg2(instr_info); type = kvm_register_read(vcpu, gpr_index); types = (vmx->nested.msrs.vpid_caps & @@ -6091,7 +6091,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu) * operand is read even if it isn't needed (e.g., for type==global) */ if (get_vmx_mem_address(vcpu, vmx_get_exit_qual(vcpu), - vmx_instruction_info, false, sizeof(operand), &gva)) + instr_info, false, sizeof(operand), &gva)) return 1; r = kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e); if (r != X86EMUL_CONTINUE) @@ -6429,16 +6429,16 @@ static bool nested_vmx_exit_handled_encls(struct kvm_vcpu *vcpu, static bool nested_vmx_exit_handled_vmcs_access(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, gpa_t bitmap) { - u64 vmx_instruction_info; unsigned long field; + u64 instr_info; u8 b; if (!nested_cpu_has_shadow_vmcs(vmcs12)) return true; /* Decode instruction info and find the field to access */ - vmx_instruction_info = vmx_get_instr_info(); - field = kvm_register_read(vcpu, (((vmx_instruction_info) >> 28) & 0xf)); + instr_info = vmx_get_instr_info(); + field = kvm_register_read(vcpu, vmx_get_instr_info_reg2(instr_info)); /* Out-of-range fields always cause a VM exit from L2 to L1 */ if (field >> 15) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8a4b578252c2..c49bc6fabae3 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6158,8 +6158,8 @@ static int handle_monitor_trap(struct kvm_vcpu *vcpu) static int handle_invpcid(struct kvm_vcpu *vcpu) { - u64 vmx_instruction_info; unsigned long type; + u64 instr_info; gva_t gva; struct { u64 pcid; @@ -6172,16 +6172,15 @@ static int handle_invpcid(struct kvm_vcpu *vcpu) return 1; } - vmx_instruction_info = vmx_get_instr_info(); - gpr_index = vmx_get_instr_info_reg2(vmx_instruction_info); + instr_info = vmx_get_instr_info(); + gpr_index = vmx_get_instr_info_reg2(instr_info); type = kvm_register_read(vcpu, gpr_index); /* According to the Intel instruction reference, the memory operand * is read even if it isn't needed (e.g., for type==all) */ if (get_vmx_mem_address(vcpu, vmx_get_exit_qual(vcpu), - vmx_instruction_info, false, - sizeof(operand), &gva)) + instr_info, false, sizeof(operand), &gva)) return 1; return kvm_handle_invpcid(vcpu, type, gva); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index a3f58a3d90e5..acb4d7ac8b0a 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -708,14 +708,54 @@ static inline u64 vmx_get_instr_info(void) return vmcs_read32(VMX_INSTRUCTION_INFO); } -static inline int vmx_get_instr_info_reg(u64 vmx_instr_info) +static inline int vmx_get_instr_info_reg(u64 instr_info) { - return (vmx_instr_info >> 3) & 0xf; + return (instr_info >> 3) & 0xf; } -static inline int vmx_get_instr_info_reg2(u64 vmx_instr_info) +static inline int vmx_get_instr_info_reg2(u64 instr_info) { - return (vmx_instr_info >> 28) & 0xf; + return (instr_info >> 28) & 0xf; +} + +static inline int vmx_get_instr_info_scaling(u64 instr_info) +{ + return instr_info & 3; +} + +static inline int vmx_get_instr_info_addr_size(u64 instr_info) +{ + return (instr_info >> 7) & 7; +} + +static inline bool vmx_get_instr_info_is_reg(u64 instr_info) +{ + return !!(instr_info & BIT(10)); +} + +static inline int vmx_get_instr_info_seg_reg(u64 instr_info) +{ + return (instr_info >> 15) & 7; +} + +static inline int vmx_get_instr_info_index_reg(u64 instr_info) +{ + return (instr_info >> 18) & 0xf; +} + +static inline bool vmx_get_instr_info_index_is_valid(u64 instr_info) +{ + return !(instr_info & BIT(22)); +} + +static inline int vmx_get_instr_info_base_reg(u64 instr_info) +{ + return (instr_info >> 23) & 0xf; +} + +static inline bool vmx_get_instr_info_base_is_valid(u64 instr_info) +{ + return !(instr_info & BIT(27)); } static inline bool vmx_can_use_ipiv(struct kvm_vcpu *vcpu) -- 2.53.0