This is a note to let you know that I've just added the patch titled
kvm: vmx: Reinstate support for CPUs without virtual NMI
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: kvm-vmx-reinstate-support-for-cpus-without-virtual-nmi.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 8a1b43922d0d1279e7936ba85c4c2a870403c95f Mon Sep 17 00:00:00 2001
From: Paolo Bonzini pbonzini@redhat.com Date: Mon, 6 Nov 2017 13:31:12 +0100 Subject: kvm: vmx: Reinstate support for CPUs without virtual NMI MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
From: Paolo Bonzini pbonzini@redhat.com
commit 8a1b43922d0d1279e7936ba85c4c2a870403c95f upstream.
This is more or less a revert of commit 2c82878b0cb3 ("KVM: VMX: require virtual NMI support", 2017-03-27); it turns out that Core 2 Duo machines only had virtual NMIs in some SKUs.
The revert is not trivial because in the meanwhile there have been several fixes to nested NMI injection. Therefore, the entire vNMI state is moved to struct loaded_vmcs.
Another change compared to before the patch is a simplification here:
if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked && !(is_guest_mode(vcpu) && nested_cpu_has_virtual_nmis( get_vmcs12(vcpu))))) {
The final condition here is always true (because nested_cpu_has_virtual_nmis is always false) and is removed.
Fixes: 2c82878b0cb38fd516fd612c67852a6bbf282003 Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1490803 Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/vmx.c | 150 +++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 106 insertions(+), 44 deletions(-)
--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -202,6 +202,10 @@ struct loaded_vmcs { bool nmi_known_unmasked; unsigned long vmcs_host_cr3; /* May not match real cr3 */ unsigned long vmcs_host_cr4; /* May not match real cr4 */ + /* Support for vnmi-less CPUs */ + int soft_vnmi_blocked; + ktime_t entry_time; + s64 vnmi_blocked_time; struct list_head loaded_vmcss_on_cpu_link; };
@@ -1286,6 +1290,11 @@ static inline bool cpu_has_vmx_invpcid(v SECONDARY_EXEC_ENABLE_INVPCID; }
+static inline bool cpu_has_virtual_nmis(void) +{ + return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS; +} + static inline bool cpu_has_vmx_wbinvd_exit(void) { return vmcs_config.cpu_based_2nd_exec_ctrl & @@ -1343,11 +1352,6 @@ static inline bool nested_cpu_has2(struc (vmcs12->secondary_vm_exec_control & bit); }
-static inline bool nested_cpu_has_virtual_nmis(struct vmcs12 *vmcs12) -{ - return vmcs12->pin_based_vm_exec_control & PIN_BASED_VIRTUAL_NMIS; -} - static inline bool nested_cpu_has_preemption_timer(struct vmcs12 *vmcs12) { return vmcs12->pin_based_vm_exec_control & @@ -3699,9 +3703,9 @@ static __init int setup_vmcs_config(stru &_vmexit_control) < 0) return -EIO;
- min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING | - PIN_BASED_VIRTUAL_NMIS; - opt = PIN_BASED_POSTED_INTR | PIN_BASED_VMX_PREEMPTION_TIMER; + min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING; + opt = PIN_BASED_VIRTUAL_NMIS | PIN_BASED_POSTED_INTR | + PIN_BASED_VMX_PREEMPTION_TIMER; if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PINBASED_CTLS, &_pin_based_exec_control) < 0) return -EIO; @@ -5667,7 +5671,8 @@ static void enable_irq_window(struct kvm
static void enable_nmi_window(struct kvm_vcpu *vcpu) { - if (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) { + if (!cpu_has_virtual_nmis() || + vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) { enable_irq_window(vcpu); return; } @@ -5707,6 +5712,19 @@ static void vmx_inject_nmi(struct kvm_vc { struct vcpu_vmx *vmx = to_vmx(vcpu);
+ if (!cpu_has_virtual_nmis()) { + /* + * Tracking the NMI-blocked state in software is built upon + * finding the next open IRQ window. This, in turn, depends on + * well-behaving guests: They have to keep IRQs disabled at + * least as long as the NMI handler runs. Otherwise we may + * cause NMI nesting, maybe breaking the guest. But as this is + * highly unlikely, we can live with the residual risk. + */ + vmx->loaded_vmcs->soft_vnmi_blocked = 1; + vmx->loaded_vmcs->vnmi_blocked_time = 0; + } + ++vcpu->stat.nmi_injections; vmx->loaded_vmcs->nmi_known_unmasked = false;
@@ -5725,6 +5743,8 @@ static bool vmx_get_nmi_mask(struct kvm_ struct vcpu_vmx *vmx = to_vmx(vcpu); bool masked;
+ if (!cpu_has_virtual_nmis()) + return vmx->loaded_vmcs->soft_vnmi_blocked; if (vmx->loaded_vmcs->nmi_known_unmasked) return false; masked = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_NMI; @@ -5736,13 +5756,20 @@ static void vmx_set_nmi_mask(struct kvm_ { struct vcpu_vmx *vmx = to_vmx(vcpu);
- vmx->loaded_vmcs->nmi_known_unmasked = !masked; - if (masked) - vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, - GUEST_INTR_STATE_NMI); - else - vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO, - GUEST_INTR_STATE_NMI); + if (!cpu_has_virtual_nmis()) { + if (vmx->loaded_vmcs->soft_vnmi_blocked != masked) { + vmx->loaded_vmcs->soft_vnmi_blocked = masked; + vmx->loaded_vmcs->vnmi_blocked_time = 0; + } + } else { + vmx->loaded_vmcs->nmi_known_unmasked = !masked; + if (masked) + vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, + GUEST_INTR_STATE_NMI); + else + vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO, + GUEST_INTR_STATE_NMI); + } }
static int vmx_nmi_allowed(struct kvm_vcpu *vcpu) @@ -5750,6 +5777,10 @@ static int vmx_nmi_allowed(struct kvm_vc if (to_vmx(vcpu)->nested.nested_run_pending) return 0;
+ if (!cpu_has_virtual_nmis() && + to_vmx(vcpu)->loaded_vmcs->soft_vnmi_blocked) + return 0; + return !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & (GUEST_INTR_STATE_MOV_SS | GUEST_INTR_STATE_STI | GUEST_INTR_STATE_NMI)); @@ -6478,6 +6509,7 @@ static int handle_ept_violation(struct k * AAK134, BY25. */ if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) && + cpu_has_virtual_nmis() && (exit_qualification & INTR_INFO_UNBLOCK_NMI)) vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
@@ -6961,7 +6993,7 @@ static struct loaded_vmcs *nested_get_cu }
/* Create a new VMCS */ - item = kmalloc(sizeof(struct vmcs02_list), GFP_KERNEL); + item = kzalloc(sizeof(struct vmcs02_list), GFP_KERNEL); if (!item) return NULL; item->vmcs02.vmcs = alloc_vmcs(); @@ -7978,6 +8010,7 @@ static int handle_pml_full(struct kvm_vc * "blocked by NMI" bit has to be set before next VM entry. */ if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) && + cpu_has_virtual_nmis() && (exit_qualification & INTR_INFO_UNBLOCK_NMI)) vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI); @@ -8822,6 +8855,25 @@ static int vmx_handle_exit(struct kvm_vc return 0; }
+ if (unlikely(!cpu_has_virtual_nmis() && + vmx->loaded_vmcs->soft_vnmi_blocked)) { + if (vmx_interrupt_allowed(vcpu)) { + vmx->loaded_vmcs->soft_vnmi_blocked = 0; + } else if (vmx->loaded_vmcs->vnmi_blocked_time > 1000000000LL && + vcpu->arch.nmi_pending) { + /* + * This CPU don't support us in finding the end of an + * NMI-blocked window if the guest runs with IRQs + * disabled. So we pull the trigger after 1 s of + * futile waiting, but inform the user about this. + */ + printk(KERN_WARNING "%s: Breaking out of NMI-blocked " + "state on VCPU %d after 1 s timeout\n", + __func__, vcpu->vcpu_id); + vmx->loaded_vmcs->soft_vnmi_blocked = 0; + } + } + if (exit_reason < kvm_vmx_max_exit_handlers && kvm_vmx_exit_handlers[exit_reason]) return kvm_vmx_exit_handlers[exit_reason](vcpu); @@ -9104,33 +9156,38 @@ static void vmx_recover_nmi_blocking(str
idtv_info_valid = vmx->idt_vectoring_info & VECTORING_INFO_VALID_MASK;
- if (vmx->loaded_vmcs->nmi_known_unmasked) - return; - /* - * Can't use vmx->exit_intr_info since we're not sure what - * the exit reason is. - */ - exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO); - unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0; - vector = exit_intr_info & INTR_INFO_VECTOR_MASK; - /* - * SDM 3: 27.7.1.2 (September 2008) - * Re-set bit "block by NMI" before VM entry if vmexit caused by - * a guest IRET fault. - * SDM 3: 23.2.2 (September 2008) - * Bit 12 is undefined in any of the following cases: - * If the VM exit sets the valid bit in the IDT-vectoring - * information field. - * If the VM exit is due to a double fault. - */ - if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi && - vector != DF_VECTOR && !idtv_info_valid) - vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, - GUEST_INTR_STATE_NMI); - else - vmx->loaded_vmcs->nmi_known_unmasked = - !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) - & GUEST_INTR_STATE_NMI); + if (cpu_has_virtual_nmis()) { + if (vmx->loaded_vmcs->nmi_known_unmasked) + return; + /* + * Can't use vmx->exit_intr_info since we're not sure what + * the exit reason is. + */ + exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO); + unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0; + vector = exit_intr_info & INTR_INFO_VECTOR_MASK; + /* + * SDM 3: 27.7.1.2 (September 2008) + * Re-set bit "block by NMI" before VM entry if vmexit caused by + * a guest IRET fault. + * SDM 3: 23.2.2 (September 2008) + * Bit 12 is undefined in any of the following cases: + * If the VM exit sets the valid bit in the IDT-vectoring + * information field. + * If the VM exit is due to a double fault. + */ + if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi && + vector != DF_VECTOR && !idtv_info_valid) + vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, + GUEST_INTR_STATE_NMI); + else + vmx->loaded_vmcs->nmi_known_unmasked = + !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) + & GUEST_INTR_STATE_NMI); + } else if (unlikely(vmx->loaded_vmcs->soft_vnmi_blocked)) + vmx->loaded_vmcs->vnmi_blocked_time += + ktime_to_ns(ktime_sub(ktime_get(), + vmx->loaded_vmcs->entry_time)); }
static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, @@ -9247,6 +9304,11 @@ static void __noclone vmx_vcpu_run(struc struct vcpu_vmx *vmx = to_vmx(vcpu); unsigned long debugctlmsr, cr3, cr4;
+ /* Record the guest's net vcpu time for enforced NMI injections. */ + if (unlikely(!cpu_has_virtual_nmis() && + vmx->loaded_vmcs->soft_vnmi_blocked)) + vmx->loaded_vmcs->entry_time = ktime_get(); + /* Don't enter VMX if guest state is invalid, let the exit handler start emulation until we arrive back to a valid state */ if (vmx->emulation_required)
Patches currently in stable-queue which might be from pbonzini@redhat.com are
queue-4.14/kvm-nvmx-set-idtr-and-gdtr-limits-when-loading-l1-host-state.patch queue-4.14/kvm-svm-obey-guest-pat.patch queue-4.14/kvm-vmx-reinstate-support-for-cpus-without-virtual-nmi.patch