- APIC read doesn't cause VM-Exit - APIC write becomes trap-like Signed-off-by: Kevin Tian <kevin.tian@xxxxxxxxx> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx> --- arch/x86/include/asm/vmx.h | 2 ++ arch/x86/kvm/lapic.c | 15 +++++++++++++++ arch/x86/kvm/lapic.h | 2 ++ arch/x86/kvm/vmx.c | 33 ++++++++++++++++++++++++++++++++- 4 files changed, 51 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h index 36ec21c..21101b6 100644 --- a/arch/x86/include/asm/vmx.h +++ b/arch/x86/include/asm/vmx.h @@ -66,6 +66,7 @@ #define EXIT_REASON_EPT_MISCONFIG 49 #define EXIT_REASON_WBINVD 54 #define EXIT_REASON_XSETBV 55 +#define EXIT_REASON_APIC_WRITE 56 #define EXIT_REASON_INVPCID 58 #define VMX_EXIT_REASONS \ @@ -141,6 +142,7 @@ #define SECONDARY_EXEC_ENABLE_VPID 0x00000020 #define SECONDARY_EXEC_WBINVD_EXITING 0x00000040 #define SECONDARY_EXEC_UNRESTRICTED_GUEST 0x00000080 +#define SECONDARY_EXEC_APIC_REGISTER_VIRT 0x00000100 #define SECONDARY_EXEC_PAUSE_LOOP_EXITING 0x00000400 #define SECONDARY_EXEC_ENABLE_INVPCID 0x00001000 diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 9392f52..0664c13 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1212,6 +1212,21 @@ void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi); +/* emulate APIC access in a trap manner */ +void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset) +{ + u32 val = 0; + + /* hw has done the conditional check and inst decode */ + offset &= 0xff0; + + apic_reg_read(vcpu->arch.apic, offset, 4, &val); + + /* TODO: optimize to just emulate side effect w/o one more write */ + apic_reg_write(vcpu->arch.apic, offset, val); +} +EXPORT_SYMBOL_GPL(kvm_apic_write_nodecode); + void kvm_free_lapic(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index e5ebf9f..9a8ee22 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -64,6 +64,8 @@ int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu); u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu); void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data); +void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset); + void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr); void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu); void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 2fd2046..4838e4f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -83,6 +83,9 @@ module_param(vmm_exclusive, bool, S_IRUGO); static bool __read_mostly fasteoi = 1; module_param(fasteoi, bool, S_IRUGO); +static bool __read_mostly enable_apicv_reg_vid; +module_param(enable_apicv_reg_vid, bool, S_IRUGO); + /* * If nested=1, nested virtualization is supported, i.e., guests may use * VMX and be a hypervisor for its own guests. If nested=0, guests may not @@ -761,6 +764,12 @@ static inline bool cpu_has_vmx_virtualize_apic_accesses(void) SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES; } +static inline bool cpu_has_vmx_apic_register_virt(void) +{ + return vmcs_config.cpu_based_2nd_exec_ctrl & + SECONDARY_EXEC_APIC_REGISTER_VIRT; +} + static inline bool cpu_has_vmx_flexpriority(void) { return cpu_has_vmx_tpr_shadow() && @@ -2498,7 +2507,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) SECONDARY_EXEC_UNRESTRICTED_GUEST | SECONDARY_EXEC_PAUSE_LOOP_EXITING | SECONDARY_EXEC_RDTSCP | - SECONDARY_EXEC_ENABLE_INVPCID; + SECONDARY_EXEC_ENABLE_INVPCID | + SECONDARY_EXEC_APIC_REGISTER_VIRT; if (adjust_vmx_controls(min2, opt2, MSR_IA32_VMX_PROCBASED_CTLS2, &_cpu_based_2nd_exec_control) < 0) @@ -2509,6 +2519,11 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) _cpu_based_exec_control &= ~CPU_BASED_TPR_SHADOW; #endif + + if (!(_cpu_based_exec_control & CPU_BASED_TPR_SHADOW)) + _cpu_based_2nd_exec_control &= ~( + SECONDARY_EXEC_APIC_REGISTER_VIRT); + if (_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_EPT) { /* CR3 accesses and invlpg don't need to cause VM Exits when EPT enabled */ @@ -2706,6 +2721,9 @@ static __init int hardware_setup(void) if (!cpu_has_vmx_ple()) ple_gap = 0; + if (!cpu_has_vmx_apic_register_virt()) + enable_apicv_reg_vid = 0; + if (nested) nested_vmx_setup_ctls_msrs(); @@ -3819,6 +3837,8 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx) exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST; if (!ple_gap) exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING; + if (!enable_apicv_reg_vid) + exec_control &= ~SECONDARY_EXEC_APIC_REGISTER_VIRT; return exec_control; } @@ -4786,6 +4806,16 @@ static int handle_apic_access(struct kvm_vcpu *vcpu) return emulate_instruction(vcpu, 0) == EMULATE_DONE; } +static int handle_apic_write(struct kvm_vcpu *vcpu) +{ + unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION); + u32 offset = exit_qualification & 0xfff; + + /* APIC-write VM exit is trap-like and thus no need to adjust IP */ + kvm_apic_write_nodecode(vcpu, offset); + return 1; +} + static int handle_task_switch(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); @@ -5725,6 +5755,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { [EXIT_REASON_VMON] = handle_vmon, [EXIT_REASON_TPR_BELOW_THRESHOLD] = handle_tpr_below_threshold, [EXIT_REASON_APIC_ACCESS] = handle_apic_access, + [EXIT_REASON_APIC_WRITE] = handle_apic_write, [EXIT_REASON_WBINVD] = handle_wbinvd, [EXIT_REASON_XSETBV] = handle_xsetbv, [EXIT_REASON_TASK_SWITCH] = handle_task_switch, -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html