On 04.11.2015 22:27, Paolo Bonzini wrote:
On 04/11/2015 20:33, Gerhard Wiesinger wrote:Signed-off-by: Gerhard Wiesinger <lists@xxxxxxxxxxxxx> --- arch/x86/kvm/svm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 2f9ed1f..e0b00fc 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -198,6 +198,10 @@ static bool npt_enabled; static int npt = true; module_param(npt, int, S_IRUGO); +/* allow backward compatibility with e.g. old DOS application */ +static int npt_task_switch_emulation = true; +module_param(npt_task_switch_emulation, int, S_IRUGO); + /* allow nested virtualization in KVM/SVM */ static int nested = true; module_param(nested, int, S_IRUGO); @@ -1177,6 +1181,9 @@ static void init_vmcb(struct vcpu_svm *svm, bool init_event) if (npt_enabled) { /* Setup VMCB for Nested Paging */ control->nested_ctl = 1; + if (!npt_task_switch_emulation) { + clr_intercept(svm, INTERCEPT_TASK_SWITCH); + } clr_intercept(svm, INTERCEPT_INVLPG); clr_exception_intercept(svm, PF_VECTOR); clr_cr_intercept(svm, INTERCEPT_CR3_READ);What is the problem you are seeing? KVM can emulate task switches; the intercept is set here because of a processor erratum that can mess them up even though, in theory, AMD supports task switching from guest mode.
See old thread: https://lists.nongnu.org/archive/html/qemu-devel/2012-04/msg01506.html Ciao, Gerhard -- 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
