From 6d77dbfc88e37c9efd5c5dd18445cfe819ae17ea Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Mon, 10 May 2010 11:16:56 +0300 Subject: [PATCH] KVM: inject #UD if instruction emulation fails and exit to userspace Do not kill VM when instruction emulation fails. Inject #UD and report failure to userspace instead. Userspace may choose to reenter guest if vcpu is in userspace (cpl == 3) in which case guest OS will kill offending process and continue running. Signed-off-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/mmu.c | 5 +--- arch/x86/kvm/svm.c | 10 +++----- arch/x86/kvm/vmx.c | 28 +++------------------ arch/x86/kvm/x86.c | 43 ++++++++++++++------------------- 5 files changed, 26 insertions(+), 61 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 2ca1867ed97a..0c06148fa3b1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -576,7 +576,6 @@ enum emulation_result { #define EMULTYPE_SKIP (1 << 2) int emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, u16 error_code, int emulation_type); -void kvm_report_emulation_failure(struct kvm_vcpu *cvpu, const char *context); void realmode_lgdt(struct kvm_vcpu *vcpu, u16 size, unsigned long address); void realmode_lidt(struct kvm_vcpu *vcpu, u16 size, unsigned long address); diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index be981b1f1881..4a02dee1f2b5 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2814,11 +2814,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code) return 1; case EMULATE_DO_MMIO: ++vcpu->stat.mmio_exits; - return 0; + /* fall through */ case 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; default: BUG(); diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 41fe0381a1ae..134260c36ce2 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1535,7 +1535,7 @@ static int io_interception(struct vcpu_svm *svm) string = (io_info & SVM_IOIO_STR_MASK) != 0; in = (io_info & SVM_IOIO_TYPE_MASK) != 0; if (string || in) - return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO); + return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE; port = io_info >> 16; size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT; @@ -2386,16 +2386,12 @@ static int iret_interception(struct vcpu_svm *svm) static int invlpg_interception(struct vcpu_svm *svm) { - if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE) - pr_unimpl(&svm->vcpu, "%s: failed\n", __func__); - return 1; + return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE; } static int emulate_on_interception(struct vcpu_svm *svm) { - if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE) - pr_unimpl(&svm->vcpu, "%s: failed\n", __func__); - return 1; + return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE; } static int cr8_write_interception(struct vcpu_svm *svm) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 598931734251..a82cfa1e2a40 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3070,7 +3070,7 @@ static int handle_io(struct kvm_vcpu *vcpu) ++vcpu->stat.io_exits; if (string || in) - return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO); + return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE; port = exit_qualification >> 16; size = (exit_qualification & 7) + 1; @@ -3327,22 +3327,7 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu) static int handle_apic_access(struct kvm_vcpu *vcpu) { - unsigned long exit_qualification; - enum emulation_result er; - unsigned long offset; - - exit_qualification = vmcs_readl(EXIT_QUALIFICATION); - offset = exit_qualification & 0xffful; - - er = emulate_instruction(vcpu, 0, 0, 0); - - if (er != EMULATE_DONE) { - printk(KERN_ERR - "Fail to handle apic access vmexit! Offset is 0x%lx\n", - offset); - return -ENOEXEC; - } - return 1; + return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE; } static int handle_task_switch(struct kvm_vcpu *vcpu) @@ -3554,13 +3539,8 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu) goto out; } - if (err != EMULATE_DONE) { - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; - vcpu->run->internal.ndata = 0; - ret = 0; - goto out; - } + if (err != EMULATE_DONE) + return 0; if (signal_pending(current)) goto out; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fc5611b4007f..ae9d6f3e5d0d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3639,24 +3639,6 @@ int emulator_set_dr(int dr, unsigned long value, struct kvm_vcpu *vcpu) return __kvm_set_dr(vcpu, dr, value); } -void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context) -{ - u8 opcodes[4]; - unsigned long rip = kvm_rip_read(vcpu); - unsigned long rip_linear; - - if (!printk_ratelimit()) - return; - - rip_linear = rip + get_segment_base(vcpu, VCPU_SREG_CS); - - kvm_read_guest_virt(rip_linear, (void *)opcodes, 4, vcpu, NULL); - - printk(KERN_ERR "emulation failed (%s) rip %lx %02x %02x %02x %02x\n", - context, rip, opcodes[0], opcodes[1], opcodes[2], opcodes[3]); -} -EXPORT_SYMBOL_GPL(kvm_report_emulation_failure); - static u64 mk_cr_64(u64 curr_cr, u32 new_val) { return (curr_cr & ~((1ULL << 32) - 1)) | new_val; @@ -3863,6 +3845,19 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu) kvm_queue_exception(vcpu, ctxt->exception); } +static int handle_emulation_failure(struct kvm_vcpu *vcpu) +{ + struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt; + + ++vcpu->stat.insn_emulation_fail; + trace_kvm_emulate_insn_failed(vcpu); + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; + vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; + vcpu->run->internal.ndata = 0; + kvm_queue_exception(vcpu, UD_VECTOR); + return EMULATE_FAIL; +} + int emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, u16 error_code, @@ -3931,11 +3926,11 @@ int emulate_instruction(struct kvm_vcpu *vcpu, ++vcpu->stat.insn_emulation; if (r) { - ++vcpu->stat.insn_emulation_fail; - trace_kvm_emulate_insn_failed(vcpu); if (kvm_mmu_unprotect_page_virt(vcpu, cr2)) return EMULATE_DONE; - return EMULATE_FAIL; + if (emulation_type & EMULTYPE_SKIP) + return EMULATE_FAIL; + return handle_emulation_failure(vcpu); } } @@ -3960,9 +3955,7 @@ restart: if (kvm_mmu_unprotect_page_virt(vcpu, cr2)) return EMULATE_DONE; - trace_kvm_emulate_insn_failed(vcpu); - kvm_report_emulation_failure(vcpu, "mmio"); - return EMULATE_FAIL; + return handle_emulation_failure(vcpu); } toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility); @@ -4798,7 +4791,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); - if (r == EMULATE_DO_MMIO) { + if (r != EMULATE_DONE) { r = 0; goto out; } -- 2.20.1