Set injected-event data when injecting a #PF, #DB, or #NM caused by extended feature disable using FRED event delivery, and save original-event data for being used as injected-event data.
Unlike IDT using some extra CPU register as part of an event context, e.g., %cr2 for #PF, FRED saves a complete event context in its stack frame, e.g., FRED saves the faulting linear address of a #PF into the event data field defined in its stack frame. Thus a new VMX control field called injected-event data is added to provide the event data that will be pushed into a FRED stack frame for VM entries that inject an event using FRED event delivery. In addition, a new VM exit information field called original-event data is added to store the event data that would have saved into a FRED stack frame for VM exits that occur during FRED event delivery. After such a VM exit is handled to allow the original-event to be delivered, the data in the original-event data VMCS field needs to be set into the injected-event data VMCS field for the injection of the original event. Signed-off-by: Xin Li <[email protected]> Tested-by: Shan Kang <[email protected]> --- Change since v1: * Document event data should be equal to CR2/DR6/IA32_XFD_ERR instead of using WARN_ON() (Chao Gao). * Zero event data if a #NM was not caused by extended feature disable (Chao Gao). --- arch/x86/include/asm/vmx.h | 4 ++ arch/x86/kvm/vmx/vmx.c | 109 ++++++++++++++++++++++++++++--------- arch/x86/kvm/vmx/vmx.h | 1 + arch/x86/kvm/x86.c | 10 +++- 4 files changed, 95 insertions(+), 29 deletions(-) diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h index 4889754415b5..6b796c5c9c2b 100644 --- a/arch/x86/include/asm/vmx.h +++ b/arch/x86/include/asm/vmx.h @@ -256,8 +256,12 @@ enum vmcs_field { PID_POINTER_TABLE_HIGH = 0x00002043, SECONDARY_VM_EXIT_CONTROLS = 0x00002044, SECONDARY_VM_EXIT_CONTROLS_HIGH = 0x00002045, + INJECTED_EVENT_DATA = 0x00002052, + INJECTED_EVENT_DATA_HIGH = 0x00002053, GUEST_PHYSICAL_ADDRESS = 0x00002400, GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401, + ORIGINAL_EVENT_DATA = 0x00002404, + ORIGINAL_EVENT_DATA_HIGH = 0x00002405, VMCS_LINK_POINTER = 0x00002800, VMCS_LINK_POINTER_HIGH = 0x00002801, GUEST_IA32_DEBUGCTL = 0x00002802, diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ee61d2c25cb0..f622fb90a098 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1871,9 +1871,29 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu) vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, vmx->vcpu.arch.event_exit_inst_len); intr_info |= INTR_TYPE_SOFT_EXCEPTION; - } else + } else { intr_info |= INTR_TYPE_HARD_EXCEPTION; + if (kvm_is_fred_enabled(vcpu)) { + u64 event_data = 0; + + if (is_debug(intr_info)) + /* + * Compared to DR6, FRED #DB event data saved on + * the stack frame have bits 4 ~ 11 and 16 ~ 31 + * inverted, i.e., + * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL + */ + event_data = vcpu->arch.dr6 ^ DR6_RESERVED; + else if (is_page_fault(intr_info)) + event_data = vcpu->arch.cr2; + else if (is_nm_fault(intr_info)) + event_data = to_vmx(vcpu)->fred_xfd_event_data; + + vmcs_write64(INJECTED_EVENT_DATA, event_data); + } + } + vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info); vmx_clear_hlt(vcpu); @@ -7082,8 +7102,11 @@ static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu) * * Queuing exception is done in vmx_handle_exit. See comment there. */ - if (vcpu->arch.guest_fpu.fpstate->xfd) + if (vcpu->arch.guest_fpu.fpstate->xfd) { rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err); + to_vmx(vcpu)->fred_xfd_event_data = vcpu->arch.cr0 & X86_CR0_TS + ? 0 : vcpu->arch.guest_fpu.xfd_err; + } } static void handle_exception_irqoff(struct vcpu_vmx *vmx) @@ -7199,29 +7222,28 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx) vmx->loaded_vmcs->entry_time)); } -static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, - u32 idt_vectoring_info, - int instr_len_field, - int error_code_field) +static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring) { - u8 vector; - int type; - bool idtv_info_valid; - - idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK; + u32 event_id = vectoring ? to_vmx(vcpu)->idt_vectoring_info + : vmcs_read32(VM_ENTRY_INTR_INFO_FIELD); + int instr_len_field = vectoring ? VM_EXIT_INSTRUCTION_LEN + : VM_ENTRY_INSTRUCTION_LEN; + int error_code_field = vectoring ? IDT_VECTORING_ERROR_CODE + : VM_ENTRY_EXCEPTION_ERROR_CODE; + int event_data_field = vectoring ? ORIGINAL_EVENT_DATA + : INJECTED_EVENT_DATA; + u8 vector = event_id & INTR_INFO_VECTOR_MASK; + int type = event_id & INTR_INFO_INTR_TYPE_MASK; vcpu->arch.nmi_injected = false; kvm_clear_exception_queue(vcpu); kvm_clear_interrupt_queue(vcpu); - if (!idtv_info_valid) + if (!(event_id & INTR_INFO_VALID_MASK)) return; kvm_make_request(KVM_REQ_EVENT, vcpu); - vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK; - type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK; - switch (type) { case INTR_TYPE_NMI_INTR: vcpu->arch.nmi_injected = true; @@ -7236,10 +7258,31 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field); fallthrough; case INTR_TYPE_HARD_EXCEPTION: - if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) { - u32 err = vmcs_read32(error_code_field); - kvm_requeue_exception_e(vcpu, vector, err); - } else + if (kvm_is_fred_enabled(vcpu)) { + /* Save event data for being used as injected-event data */ + u64 event_data = vmcs_read64(event_data_field); + + switch (vector) { + case DB_VECTOR: + /* %dr6 should be equal to (event_data ^ DR6_RESERVED) */ + vcpu->arch.dr6 = event_data ^ DR6_RESERVED; + break; + case NM_VECTOR: + to_vmx(vcpu)->fred_xfd_event_data = event_data; + break; + case PF_VECTOR: + /* %cr2 should be equal to event_data */ + vcpu->arch.cr2 = event_data; + break; + default: + WARN_ON(event_data != 0); + break; + } + } + + if (event_id & INTR_INFO_DELIVER_CODE_MASK) + kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field)); + else kvm_requeue_exception(vcpu, vector); break; case INTR_TYPE_SOFT_INTR: @@ -7255,18 +7298,12 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, static void vmx_complete_interrupts(struct vcpu_vmx *vmx) { - __vmx_complete_interrupts(&vmx->vcpu, vmx->idt_vectoring_info, - VM_EXIT_INSTRUCTION_LEN, - IDT_VECTORING_ERROR_CODE); + __vmx_complete_interrupts(&vmx->vcpu, true); } static void vmx_cancel_injection(struct kvm_vcpu *vcpu) { - __vmx_complete_interrupts(vcpu, - vmcs_read32(VM_ENTRY_INTR_INFO_FIELD), - VM_ENTRY_INSTRUCTION_LEN, - VM_ENTRY_EXCEPTION_ERROR_CODE); - + __vmx_complete_interrupts(vcpu, false); vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0); } @@ -7382,6 +7419,24 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, vmx_disable_fb_clear(vmx); + /* + * %cr2 needs to be saved after a VM exit and restored before a VM + * entry in case a VM exit happens immediately after delivery of a + * guest #PF but before guest reads %cr2. + * + * A FRED guest should read its #PF faulting linear address from + * the event data field in its FRED stack frame instead of %cr2. + * But the FRED 5.0 spec still requires a FRED CPU to update %cr2 + * in the normal way, thus %cr2 is still updated even for a FRED + * guest. + * + * Note, an NMI could interrupt KVM: + * 1) after VM exit but before CR2 is saved. + * 2) after CR2 is restored but before VM entry. + * And a #PF could happen durng NMI handlng, which overwrites %cr2. + * Thus exc_nmi() should save and restore %cr2 upon entering and + * before leaving to make sure %cr2 not corrupted. + */ if (vcpu->arch.cr2 != native_read_cr2()) native_write_cr2(vcpu->arch.cr2); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 176ad39be406..d5738c5a4814 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -266,6 +266,7 @@ struct vcpu_vmx { u32 exit_intr_info; u32 idt_vectoring_info; ulong rflags; + u64 fred_xfd_event_data; /* * User return MSRs are always emulated when enabled in the guest, but diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4e8d60f248e3..00c0062726ae 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -680,8 +680,14 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu, vcpu->arch.exception.injected = true; if (WARN_ON_ONCE(has_payload)) { /* - * A reinjected event has already - * delivered its payload. + * For a reinjected event, KVM delivers its + * payload through: + * #PF: save %cr2 into arch.cr2 immediately + * after VM exits. + * #DB: save %dr6 into arch.dr6 later in + * sync_dirty_debug_regs(). + * + * For FRED guest, see __vmx_complete_interrupts(). */ has_payload = false; payload = 0; -- 2.43.0
