diff options
| author | Gleb Natapov | 2009-03-30 16:03:24 +0300 |
|---|---|---|
| committer | Avi Kivity | 2009-06-10 11:48:37 +0300 |
| commit | b237ac37a149e8b56436fabf093532483bff13b0 (patch) | |
| tree | c5b8070059f88085472ce5fefc11f41d62b53d6a | |
| parent | 8843419048e500f8f38df555bca1bf7948804b7f (diff) | |
KVM: Fix task switch back link handling.
Back link is written to a wrong TSS now.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 70ee81e50d99..adcf73871a9d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3717,7 +3717,6 @@ static void save_state_to_tss32(struct kvm_vcpu *vcpu, tss->fs = get_segment_selector(vcpu, VCPU_SREG_FS); tss->gs = get_segment_selector(vcpu, VCPU_SREG_GS); tss->ldt_selector = get_segment_selector(vcpu, VCPU_SREG_LDTR); - tss->prev_task_link = get_segment_selector(vcpu, VCPU_SREG_TR); } static int load_state_from_tss32(struct kvm_vcpu *vcpu, @@ -3814,8 +3813,8 @@ static int load_state_from_tss16(struct kvm_vcpu *vcpu, } static int kvm_task_switch_16(struct kvm_vcpu *vcpu, u16 tss_selector, - u32 old_tss_base, - struct desc_struct *nseg_desc) + u16 old_tss_sel, u32 old_tss_base, + struct desc_struct *nseg_desc) { struct tss_segment_16 tss_segment_16; int ret = 0; @@ -3834,6 +3833,16 @@ static int kvm_task_switch_16(struct kvm_vcpu *vcpu, u16 tss_selector, &tss_segment_16, sizeof tss_segment_16)) goto out; + if (old_tss_sel != 0xffff) { + tss_segment_16.prev_task_link = old_tss_sel; + + if (kvm_write_guest(vcpu->kvm, + get_tss_base_addr(vcpu, nseg_desc), + &tss_segment_16.prev_task_link, + sizeof tss_segment_16.prev_task_link)) + goto out; + } + if (load_state_from_tss16(vcpu, &tss_segment_16)) goto out; @@ -3843,7 +3852,7 @@ out: } static int kvm_task_switch_32(struct kvm_vcpu *vcpu, u16 tss_selector, - u32 old_tss_base, + u16 old_tss_sel, u32 old_tss_base, struct desc_struct *nseg_desc) { struct tss_segment_32 tss_segment_32; @@ -3863,6 +3872,16 @@ static int kvm_task_switch_32(struct kvm_vcpu *vcpu, u16 tss_selector, &tss_segment_32, sizeof tss_segment_32)) goto out; + if (old_tss_sel != 0xffff) { + tss_segment_32.prev_task_link = old_tss_sel; + + if (kvm_write_guest(vcpu->kvm, + get_tss_base_addr(vcpu, nseg_desc), + &tss_segment_32.prev_task_link, + sizeof tss_segment_32.prev_task_link)) + goto out; + } + if (load_state_from_tss32(vcpu, &tss_segment_32)) goto out; @@ -3918,12 +3937,17 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason) kvm_x86_ops->skip_emulated_instruction(vcpu); + /* set back link to prev task only if NT bit is set in eflags + note that old_tss_sel is not used afetr this point */ + if (reason != TASK_SWITCH_CALL && reason != TASK_SWITCH_GATE) + old_tss_sel = 0xffff; + if (nseg_desc.type & 8) - ret = kvm_task_switch_32(vcpu, tss_selector, old_tss_base, - &nseg_desc); + ret = kvm_task_switch_32(vcpu, tss_selector, old_tss_sel, + old_tss_base, &nseg_desc); else - ret = kvm_task_switch_16(vcpu, tss_selector, old_tss_base, - &nseg_desc); + ret = kvm_task_switch_16(vcpu, tss_selector, old_tss_sel, + old_tss_base, &nseg_desc); if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE) { u32 eflags = kvm_x86_ops->get_rflags(vcpu); |