From 776e58ea3d3735f85678155398241d2513afa67a Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Sun, 13 Mar 2011 12:34:27 +0200 Subject: [PATCH] KVM: unbreak userspace that does not sets tss address Commit 6440e5967bc broke old userspaces that do not set tss address before entering vcpu. Unbreak it by setting tss address to a safe value on the first vcpu entry. New userspaces should set tss address, so print warning in case it doesn't. Signed-off-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/vmx.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index d8475a26add6..5b4cdcbd154c 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -180,6 +180,7 @@ static u64 construct_eptp(unsigned long root_hpa); static void kvm_cpu_vmxon(u64 addr); static void kvm_cpu_vmxoff(void); static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3); +static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr); static DEFINE_PER_CPU(struct vmcs *, vmxarea); static DEFINE_PER_CPU(struct vmcs *, current_vmcs); @@ -1762,6 +1763,18 @@ static void enter_rmode(struct kvm_vcpu *vcpu) vmx->emulation_required = 1; vmx->rmode.vm86_active = 1; + /* + * Very old userspace does not call KVM_SET_TSS_ADDR before entering + * vcpu. Call it here with phys address pointing 16M below 4G. + */ + if (!vcpu->kvm->arch.tss_addr) { + printk_once(KERN_WARNING "kvm: KVM_SET_TSS_ADDR need to be " + "called before entering vcpu\n"); + srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); + vmx_set_tss_addr(vcpu->kvm, 0xfeffd000); + vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); + } + vmx->rmode.tr.selector = vmcs_read16(GUEST_TR_SELECTOR); vmx->rmode.tr.base = vmcs_readl(GUEST_TR_BASE); vmcs_writel(GUEST_TR_BASE, rmode_tss_base(vcpu->kvm)); -- 2.20.1