KVM: x86: Rework guest single-step flag injection and filtering
Push TF and RF injection and filtering on guest single-stepping into the vender get/set_rflags callbacks. This makes the whole mechanism more robust wrt user space IOCTL order and instruction emulations. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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a68a6a7282
Коммит
91586a3b7d
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@ -614,6 +614,9 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l);
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int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
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int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data);
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unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu);
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void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);
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void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
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void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
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void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long cr2,
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@ -235,6 +235,25 @@ bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl)
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}
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EXPORT_SYMBOL_GPL(kvm_require_cpl);
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unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu)
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{
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unsigned long rflags;
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rflags = kvm_x86_ops->get_rflags(vcpu);
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if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
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rflags &= ~(unsigned long)(X86_EFLAGS_TF | X86_EFLAGS_RF);
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return rflags;
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}
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EXPORT_SYMBOL_GPL(kvm_get_rflags);
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void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
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{
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if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
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rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
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kvm_x86_ops->set_rflags(vcpu, rflags);
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}
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EXPORT_SYMBOL_GPL(kvm_set_rflags);
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/*
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* Load the pae pdptrs. Return true is they are all valid.
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*/
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@ -2777,7 +2796,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
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kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
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vcpu->arch.emulate_ctxt.vcpu = vcpu;
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vcpu->arch.emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
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vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);
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vcpu->arch.emulate_ctxt.mode =
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(vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)
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? X86EMUL_MODE_REAL : cs_l
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@ -2855,7 +2874,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
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return EMULATE_DO_MMIO;
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}
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kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
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kvm_set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
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if (vcpu->mmio_is_write) {
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vcpu->mmio_needed = 0;
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@ -3291,7 +3310,7 @@ void realmode_lmsw(struct kvm_vcpu *vcpu, unsigned long msw,
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unsigned long *rflags)
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{
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kvm_lmsw(vcpu, msw);
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*rflags = kvm_x86_ops->get_rflags(vcpu);
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*rflags = kvm_get_rflags(vcpu);
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}
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unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr)
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@ -3329,7 +3348,7 @@ void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long val,
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switch (cr) {
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case 0:
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kvm_set_cr0(vcpu, mk_cr_64(vcpu->arch.cr0, val));
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*rflags = kvm_x86_ops->get_rflags(vcpu);
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*rflags = kvm_get_rflags(vcpu);
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break;
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case 2:
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vcpu->arch.cr2 = val;
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@ -3460,7 +3479,7 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu)
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{
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struct kvm_run *kvm_run = vcpu->run;
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kvm_run->if_flag = (kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
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kvm_run->if_flag = (kvm_get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
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kvm_run->cr8 = kvm_get_cr8(vcpu);
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kvm_run->apic_base = kvm_get_apic_base(vcpu);
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if (irqchip_in_kernel(vcpu->kvm))
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@ -3840,13 +3859,7 @@ int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
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#endif
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regs->rip = kvm_rip_read(vcpu);
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regs->rflags = kvm_x86_ops->get_rflags(vcpu);
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/*
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* Don't leak debug flags in case they were set for guest debugging
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*/
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if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
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regs->rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
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regs->rflags = kvm_get_rflags(vcpu);
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vcpu_put(vcpu);
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@ -3874,12 +3887,10 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
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kvm_register_write(vcpu, VCPU_REGS_R13, regs->r13);
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kvm_register_write(vcpu, VCPU_REGS_R14, regs->r14);
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kvm_register_write(vcpu, VCPU_REGS_R15, regs->r15);
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#endif
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kvm_rip_write(vcpu, regs->rip);
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kvm_x86_ops->set_rflags(vcpu, regs->rflags);
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kvm_set_rflags(vcpu, regs->rflags);
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vcpu->arch.exception.pending = false;
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@ -4098,7 +4109,7 @@ static int is_vm86_segment(struct kvm_vcpu *vcpu, int seg)
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{
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return (seg != VCPU_SREG_LDTR) &&
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(seg != VCPU_SREG_TR) &&
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(kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_VM);
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(kvm_get_rflags(vcpu) & X86_EFLAGS_VM);
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}
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int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
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@ -4126,7 +4137,7 @@ static void save_state_to_tss32(struct kvm_vcpu *vcpu,
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{
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tss->cr3 = vcpu->arch.cr3;
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tss->eip = kvm_rip_read(vcpu);
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tss->eflags = kvm_x86_ops->get_rflags(vcpu);
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tss->eflags = kvm_get_rflags(vcpu);
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tss->eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
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tss->ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
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tss->edx = kvm_register_read(vcpu, VCPU_REGS_RDX);
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@ -4150,7 +4161,7 @@ static int load_state_from_tss32(struct kvm_vcpu *vcpu,
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kvm_set_cr3(vcpu, tss->cr3);
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kvm_rip_write(vcpu, tss->eip);
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kvm_x86_ops->set_rflags(vcpu, tss->eflags | 2);
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kvm_set_rflags(vcpu, tss->eflags | 2);
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kvm_register_write(vcpu, VCPU_REGS_RAX, tss->eax);
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kvm_register_write(vcpu, VCPU_REGS_RCX, tss->ecx);
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@ -4188,7 +4199,7 @@ static void save_state_to_tss16(struct kvm_vcpu *vcpu,
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struct tss_segment_16 *tss)
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{
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tss->ip = kvm_rip_read(vcpu);
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tss->flag = kvm_x86_ops->get_rflags(vcpu);
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tss->flag = kvm_get_rflags(vcpu);
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tss->ax = kvm_register_read(vcpu, VCPU_REGS_RAX);
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tss->cx = kvm_register_read(vcpu, VCPU_REGS_RCX);
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tss->dx = kvm_register_read(vcpu, VCPU_REGS_RDX);
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@ -4209,7 +4220,7 @@ static int load_state_from_tss16(struct kvm_vcpu *vcpu,
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struct tss_segment_16 *tss)
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{
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kvm_rip_write(vcpu, tss->ip);
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kvm_x86_ops->set_rflags(vcpu, tss->flag | 2);
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kvm_set_rflags(vcpu, tss->flag | 2);
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kvm_register_write(vcpu, VCPU_REGS_RAX, tss->ax);
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kvm_register_write(vcpu, VCPU_REGS_RCX, tss->cx);
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kvm_register_write(vcpu, VCPU_REGS_RDX, tss->dx);
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@ -4355,8 +4366,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
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}
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if (reason == TASK_SWITCH_IRET) {
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u32 eflags = kvm_x86_ops->get_rflags(vcpu);
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kvm_x86_ops->set_rflags(vcpu, eflags & ~X86_EFLAGS_NT);
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u32 eflags = kvm_get_rflags(vcpu);
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kvm_set_rflags(vcpu, eflags & ~X86_EFLAGS_NT);
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}
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/* set back link to prev task only if NT bit is set in eflags
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@ -4377,8 +4388,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
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old_tss_base, &nseg_desc);
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if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE) {
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u32 eflags = kvm_x86_ops->get_rflags(vcpu);
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kvm_x86_ops->set_rflags(vcpu, eflags | X86_EFLAGS_NT);
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u32 eflags = kvm_get_rflags(vcpu);
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kvm_set_rflags(vcpu, eflags | X86_EFLAGS_NT);
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}
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if (reason != TASK_SWITCH_IRET) {
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@ -4473,12 +4484,15 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
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struct kvm_guest_debug *dbg)
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{
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unsigned long rflags;
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int old_debug;
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int i;
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vcpu_load(vcpu);
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old_debug = vcpu->guest_debug;
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/*
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* Read rflags as long as potentially injected trace flags are still
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* filtered out.
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*/
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rflags = kvm_get_rflags(vcpu);
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vcpu->guest_debug = dbg->control;
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if (!(vcpu->guest_debug & KVM_GUESTDBG_ENABLE))
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@ -4495,12 +4509,11 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
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vcpu->arch.switch_db_regs = (vcpu->arch.dr7 & DR7_BP_EN_MASK);
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}
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rflags = kvm_x86_ops->get_rflags(vcpu);
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if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
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rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
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else if (old_debug & KVM_GUESTDBG_SINGLESTEP)
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rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
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kvm_x86_ops->set_rflags(vcpu, rflags);
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/*
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* Trigger an rflags update that will inject or remove the trace
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* flags.
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*/
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kvm_set_rflags(vcpu, rflags);
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kvm_x86_ops->set_guest_debug(vcpu, dbg);
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