From 7f5d8b5600b5294137886b46bf00ef811d0fdf32 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 24 Feb 2010 18:59:18 +0100 Subject: [PATCH] KVM: SVM: Handle nested selective_cr0 intercept correctly If we have the following situation with nested svm: 1. Host KVM intercepts cr0 writes 2. Guest hypervisor intercepts only selective cr0 writes Then we get an cr0 write intercept which is handled on the host. But that intercepts may actually be a selective cr0 intercept for the guest. This patch checks for this condition and injects a selective cr0 intercept if needed. Signed-off-by: Joerg Roedel Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index b4aac5c7ad8..631d2e54449 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1043,6 +1043,27 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) { struct vcpu_svm *svm = to_svm(vcpu); + if (is_nested(svm)) { + /* + * We are here because we run in nested mode, the host kvm + * intercepts cr0 writes but the l1 hypervisor does not. + * But the L1 hypervisor may intercept selective cr0 writes. + * This needs to be checked here. + */ + unsigned long old, new; + + /* Remove bits that would trigger a real cr0 write intercept */ + old = vcpu->arch.cr0 & SVM_CR0_SELECTIVE_MASK; + new = cr0 & SVM_CR0_SELECTIVE_MASK; + + if (old == new) { + /* cr0 write with ts and mp unchanged */ + svm->vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE; + if (nested_svm_exit_handled(svm) == NESTED_EXIT_DONE) + return; + } + } + #ifdef CONFIG_X86_64 if (vcpu->arch.efer & EFER_LME) { if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) { -- 2.11.4.GIT