diff options
| author | Gleb Natapov | 2012-12-12 18:10:51 +0100 |
|---|---|---|
| committer | Gleb Natapov | 2012-12-23 13:01:03 +0100 |
| commit | c6ad115348035f474d6fb81005bb4764bdd128ef (patch) | |
| tree | 5db62808fcba00af9102abbc78fcbe3eb0d649c1 /arch/x86/kvm/vmx.c | |
| parent | KVM: VMX: relax check for CS register in rmode_segment_valid() (diff) | |
| download | kernel-qcow2-linux-c6ad115348035f474d6fb81005bb4764bdd128ef.tar.gz kernel-qcow2-linux-c6ad115348035f474d6fb81005bb4764bdd128ef.tar.xz kernel-qcow2-linux-c6ad115348035f474d6fb81005bb4764bdd128ef.zip | |
KVM: VMX: return correct segment limit and flags for CS/SS registers in real mode
VMX without unrestricted mode cannot virtualize real mode, so if
emulate_invalid_guest_state=0 kvm uses vm86 mode to approximate
it. Sometimes, when guest moves from protected mode to real mode, it
leaves segment descriptors in a state not suitable for use by vm86 mode
virtualization, so we keep shadow copy of segment descriptors for internal
use and load fake register to VMCS for guest entry to succeed. Till
now we kept shadow for all segments except SS and CS (for SS and CS we
returned parameters directly from VMCS), but since commit a5625189f6810
emulator enforces segment limits in real mode. This causes #GP during move
from protected mode to real mode when emulator fetches first instruction
after moving to real mode since it uses incorrect CS base and limit to
linearize the %rip. Fix by keeping shadow for SS and CS too.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 7c2c05406b60..792d9cce8846 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2856,6 +2856,8 @@ static void enter_rmode(struct kvm_vcpu *vcpu) vmx_get_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_DS], VCPU_SREG_DS); vmx_get_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_FS], VCPU_SREG_FS); vmx_get_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_GS], VCPU_SREG_GS); + vmx_get_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_SS], VCPU_SREG_SS); + vmx_get_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_CS], VCPU_SREG_CS); vmx->emulation_required = 1; vmx->rmode.vm86_active = 1; @@ -3171,10 +3173,7 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx = to_vmx(vcpu); u32 ar; - if (vmx->rmode.vm86_active - && (seg == VCPU_SREG_TR || seg == VCPU_SREG_ES - || seg == VCPU_SREG_DS || seg == VCPU_SREG_FS - || seg == VCPU_SREG_GS)) { + if (vmx->rmode.vm86_active && seg != VCPU_SREG_LDTR) { *var = vmx->rmode.segs[seg]; if (seg == VCPU_SREG_TR || var->selector == vmx_read_guest_seg_selector(vmx, seg)) |