From acb5451789f21ad51215897bb8f9306a05e8acd4 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Thu, 15 Apr 2010 21:03:50 +0300 Subject: [PATCH] KVM: prevent spurious exit to userspace during task switch emulation. If kvm_task_switch() fails code exits to userspace without specifying exit reason, so the previous exit reason is reused by userspace. Fix this by specifying exit reason correctly. Signed-off-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/svm.c | 10 ++++++++-- arch/x86/kvm/vmx.c | 8 ++++++-- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 78af522..ab78eb8 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2266,8 +2266,14 @@ static int task_switch_interception(struct vcpu_svm *svm) (int_vec == OF_VECTOR || int_vec == BP_VECTOR))) skip_emulated_instruction(&svm->vcpu); - return kvm_task_switch(&svm->vcpu, tss_selector, reason, - has_error_code, error_code); + if (kvm_task_switch(&svm->vcpu, tss_selector, reason, + has_error_code, error_code) == EMULATE_FAIL) { + svm->vcpu.run->exit_reason = KVM_EXIT_INTERNAL_ERROR; + svm->vcpu.run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; + svm->vcpu.run->internal.ndata = 0; + return 0; + } + return 1; } static int cpuid_interception(struct vcpu_svm *svm) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 1b38d8a..6e5e75e 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3316,9 +3316,13 @@ static int handle_task_switch(struct kvm_vcpu *vcpu) type != INTR_TYPE_NMI_INTR)) skip_emulated_instruction(vcpu); - if (!kvm_task_switch(vcpu, tss_selector, reason, has_error_code, - error_code)) + if (kvm_task_switch(vcpu, tss_selector, reason, + has_error_code, error_code) == EMULATE_FAIL) { + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; + vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; + vcpu->run->internal.ndata = 0; return 0; + } /* clear all local breakpoint enable flags */ vmcs_writel(GUEST_DR7, vmcs_readl(GUEST_DR7) & ~55); -- 2.7.4