Fix for KVM regression on some machines (rhbz 1490803)

2 files changed, 300 insertions, 0 deletions

diff --git a/1-2-kvm-vmx-Reinstate-support-for-CPUs-without-virtual-NMI.patch b/1-2-kvm-vmx-Reinstate-support-for-CPUs-without-virtual-NMI.patch
new file mode 100644
index 000000000..ca079af42
--- /dev/null
+++ b/1-2-kvm-vmx-Reinstate-support-for-CPUs-without-virtual-NMI.patch
@@ -0,0 +1,296 @@
+From patchwork Mon Nov  6 12:31:12 2017
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [1/2] kvm: vmx: Reinstate support for CPUs without virtual NMI
+From: Paolo Bonzini <pbonzini@redhat.com>
+X-Patchwork-Id: 10043403
+Message-Id: <1509971473-74491-2-git-send-email-pbonzini@redhat.com>
+To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
+Cc: rkrcmar@redhat.com, stable@vger.kernel.org
+Date: Mon,  6 Nov 2017 13:31:12 +0100
+
+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
+Cc: stable@vger.kernel.org
+Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
+---
+ arch/x86/kvm/vmx.c | 150 +++++++++++++++++++++++++++++++++++++----------------
+ 1 file changed, 106 insertions(+), 44 deletions(-)
+
+diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
+index e6c8ffa84968..d6b3b12ae1e2 100644
+--- 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;
+ };
+ 
+@@ -1291,6 +1295,11 @@ static inline bool cpu_has_vmx_invpcid(void)
+ 		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 &
+@@ -1348,11 +1357,6 @@ static inline bool nested_cpu_has2(struct vmcs12 *vmcs12, u32 bit)
+ 		(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 &
+@@ -3712,9 +3716,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
+ 				&_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;
+@@ -5669,7 +5673,8 @@ static void enable_irq_window(struct kvm_vcpu *vcpu)
+ 
+ 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;
+ 	}
+@@ -5709,6 +5714,19 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
+ {
+ 	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;
+ 
+@@ -5727,6 +5745,8 @@ static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
+ 	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;
+@@ -5738,13 +5758,20 @@ static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
+ {
+ 	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)
+@@ -5752,6 +5779,10 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
+ 	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));
+@@ -6479,6 +6510,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
+ 	 * 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);
+ 
+@@ -6965,7 +6997,7 @@ static struct loaded_vmcs *nested_get_current_vmcs02(struct vcpu_vmx *vmx)
+ 	}
+ 
+ 	/* 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();
+@@ -7982,6 +8014,7 @@ static int handle_pml_full(struct kvm_vcpu *vcpu)
+ 	 * "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);
+@@ -8826,6 +8859,25 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
+ 		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);
+@@ -9108,33 +9160,38 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
+ 
+ 	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,
+@@ -9251,6 +9308,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
+ 	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)
diff --git a/kernel.spec b/kernel.spec
index 2532fbeaa..a91e38918 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -661,6 +661,9 @@ Patch623: 0001-PATCH-staging-rtl8822be-fix-wrong-dma-unmap-len.patch
 Patch624: v3-1-2-Input-synaptics-rmi4---RMI4-can-also-use-SMBUS-version-3.patch
 Patch625: v3-2-2-Input-synaptics---Lenovo-X1-Carbon-5-should-use-SMBUS-RMI.patch
 
+# rhbz 1490803
+Patch626: 1-2-kvm-vmx-Reinstate-support-for-CPUs-without-virtual-NMI.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -2217,6 +2220,7 @@ fi
 %changelog
 * Mon Nov 06 2017 Laura Abbott <labbott@redhat.com>
 - Patches for ThinkPad X1 Carbon Gen5 Touchpad (rhbz 1509461)
+- Fix for KVM regression on some machines (rhbz 1490803)
 
 * Mon Nov 06 2017 Justin M. Forbes <jforbes@fedoraproject.org> - 4.14.0-0.rc8.git0.1
 - Linux v4.14-rc8