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Commit f1c1da2b authored by Jan Kiszka's avatar Jan Kiszka Committed by Avi Kivity
Browse files

KVM: SVM: Keep intercepting task switching with NPT enabled 



AMD processors apparently have a bug in the hardware task switching
support when NPT is enabled. If the task switch triggers a NPF, we can
get wrong EXITINTINFO along with that fault. On resume, spurious
exceptions may then be injected into the guest.

We were able to reproduce this bug when our guest triggered #SS and the
handler were supposed to run over a separate task with not yet touched
stack pages.

Work around the issue by continuing to emulate task switches even in
NPT mode.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 7697e71f

arch/x86/kvm/svm.c

+0 −1
Original line number Original line Diff line number Diff line
@@ -1084,7 +1084,6 @@ static void init_vmcb(struct vcpu_svm *svm) 
	if (npt_enabled) {

	if (npt_enabled) {

		/* Setup VMCB for Nested Paging */

		/* Setup VMCB for Nested Paging */

		control->nested_ctl = 1;

		control->nested_ctl = 1;

		clr_intercept(svm, INTERCEPT_TASK_SWITCH);

		clr_intercept(svm, INTERCEPT_INVLPG);

		clr_intercept(svm, INTERCEPT_INVLPG);

		clr_exception_intercept(svm, PF_VECTOR);

		clr_exception_intercept(svm, PF_VECTOR);

		clr_cr_intercept(svm, INTERCEPT_CR3_READ);

		clr_cr_intercept(svm, INTERCEPT_CR3_READ);