diff options
| author | Jan Kiszka <jan.kiszka@web.de> | 2009-10-18 13:24:44 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-12-03 09:32:19 +0200 |
| commit | 94fe45da48f921d01d8ff02a0ad54ee9c326d7f0 (patch) | |
| tree | 7bf7482bcbe690313909d5f2770384f853562a2d /arch/x86 | |
| parent | ffde22ac53b6d6b1d7206f1172176a667eead778 (diff) | |
KVM: x86: Fix guest single-stepping while interruptible
Commit 705c5323 opened the doors of hell by unconditionally injecting
single-step flags as long as guest_debug signaled this. This doesn't
work when the guest branches into some interrupt or exception handler
and triggers a vmexit with flag reloading.
Fix it by saving cs:rip when user space requests single-stepping and
restricting the trace flag injection to this guest code position.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 47 |
2 files changed, 32 insertions, 19 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 36f3b53f5c2..2536fbd85b3 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -371,6 +371,10 @@ struct kvm_vcpu_arch { u64 mcg_status; u64 mcg_ctl; u64 *mce_banks; + + /* used for guest single stepping over the given code position */ + u16 singlestep_cs; + unsigned long singlestep_rip; }; struct kvm_mem_alias { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bb842db3ee7..13f30aac460 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -235,25 +235,6 @@ bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl) } EXPORT_SYMBOL_GPL(kvm_require_cpl); -unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu) -{ - unsigned long rflags; - - rflags = kvm_x86_ops->get_rflags(vcpu); - if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) - rflags &= ~(unsigned long)(X86_EFLAGS_TF | X86_EFLAGS_RF); - return rflags; -} -EXPORT_SYMBOL_GPL(kvm_get_rflags); - -void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) -{ - if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) - rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF; - kvm_x86_ops->set_rflags(vcpu, rflags); -} -EXPORT_SYMBOL_GPL(kvm_set_rflags); - /* * Load the pae pdptrs. Return true is they are all valid. */ @@ -4565,6 +4546,12 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, vcpu->arch.switch_db_regs = (vcpu->arch.dr7 & DR7_BP_EN_MASK); } + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + vcpu->arch.singlestep_cs = + get_segment_selector(vcpu, VCPU_SREG_CS); + vcpu->arch.singlestep_rip = kvm_rip_read(vcpu); + } + /* * Trigger an rflags update that will inject or remove the trace * flags. @@ -5031,6 +5018,28 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu) return kvm_x86_ops->interrupt_allowed(vcpu); } +unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu) +{ + unsigned long rflags; + + rflags = kvm_x86_ops->get_rflags(vcpu); + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) + rflags &= ~(unsigned long)(X86_EFLAGS_TF | X86_EFLAGS_RF); + return rflags; +} +EXPORT_SYMBOL_GPL(kvm_get_rflags); + +void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) +{ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP && + vcpu->arch.singlestep_cs == + get_segment_selector(vcpu, VCPU_SREG_CS) && + vcpu->arch.singlestep_rip == kvm_rip_read(vcpu)) + rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF; + kvm_x86_ops->set_rflags(vcpu, rflags); +} +EXPORT_SYMBOL_GPL(kvm_set_rflags); + EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault); |