300 lines
11 KiB
Diff
300 lines
11 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 6 Nov 2017 13:31:12 +0100
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Subject: [PATCH] kvm: vmx: Reinstate support for CPUs without virtual NMI
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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commit 8a1b43922d0d1279e7936ba85c4c2a870403c95f upstream.
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This is more or less a revert of commit 2c82878b0cb3 ("KVM: VMX: require
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virtual NMI support", 2017-03-27); it turns out that Core 2 Duo machines
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only had virtual NMIs in some SKUs.
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The revert is not trivial because in the meanwhile there have been several
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fixes to nested NMI injection. Therefore, the entire vNMI state is moved
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to struct loaded_vmcs.
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Another change compared to before the patch is a simplification here:
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if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked &&
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!(is_guest_mode(vcpu) && nested_cpu_has_virtual_nmis(
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get_vmcs12(vcpu))))) {
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The final condition here is always true (because nested_cpu_has_virtual_nmis
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is always false) and is removed.
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Fixes: 2c82878b0cb38fd516fd612c67852a6bbf282003
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Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1490803
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kvm/vmx.c | 150 +++++++++++++++++++++++++++++++++++++----------------
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1 file changed, 106 insertions(+), 44 deletions(-)
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diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
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index 5edf05ce45de..146caacd8fdd 100644
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--- a/arch/x86/kvm/vmx.c
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+++ b/arch/x86/kvm/vmx.c
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@@ -204,6 +204,10 @@ struct loaded_vmcs {
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bool nmi_known_unmasked;
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unsigned long vmcs_host_cr3; /* May not match real cr3 */
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unsigned long vmcs_host_cr4; /* May not match real cr4 */
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+ /* Support for vnmi-less CPUs */
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+ int soft_vnmi_blocked;
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+ ktime_t entry_time;
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+ s64 vnmi_blocked_time;
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struct list_head loaded_vmcss_on_cpu_link;
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};
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@@ -1290,6 +1294,11 @@ static inline bool cpu_has_vmx_invpcid(void)
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SECONDARY_EXEC_ENABLE_INVPCID;
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}
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+static inline bool cpu_has_virtual_nmis(void)
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+{
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+ return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;
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+}
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+
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static inline bool cpu_has_vmx_wbinvd_exit(void)
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{
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return vmcs_config.cpu_based_2nd_exec_ctrl &
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@@ -1341,11 +1350,6 @@ static inline bool nested_cpu_has2(struct vmcs12 *vmcs12, u32 bit)
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(vmcs12->secondary_vm_exec_control & bit);
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}
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-static inline bool nested_cpu_has_virtual_nmis(struct vmcs12 *vmcs12)
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-{
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- return vmcs12->pin_based_vm_exec_control & PIN_BASED_VIRTUAL_NMIS;
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-}
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-
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static inline bool nested_cpu_has_preemption_timer(struct vmcs12 *vmcs12)
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{
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return vmcs12->pin_based_vm_exec_control &
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@@ -3687,9 +3691,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
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&_vmexit_control) < 0)
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return -EIO;
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- min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING |
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- PIN_BASED_VIRTUAL_NMIS;
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- opt = PIN_BASED_POSTED_INTR | PIN_BASED_VMX_PREEMPTION_TIMER;
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+ min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING;
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+ opt = PIN_BASED_VIRTUAL_NMIS | PIN_BASED_POSTED_INTR |
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+ PIN_BASED_VMX_PREEMPTION_TIMER;
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if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PINBASED_CTLS,
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&_pin_based_exec_control) < 0)
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return -EIO;
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@@ -5549,7 +5553,8 @@ static void enable_irq_window(struct kvm_vcpu *vcpu)
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static void enable_nmi_window(struct kvm_vcpu *vcpu)
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{
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- if (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
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+ if (!cpu_has_virtual_nmis() ||
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+ vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
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enable_irq_window(vcpu);
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return;
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}
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@@ -5589,6 +5594,19 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
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{
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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+ if (!cpu_has_virtual_nmis()) {
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+ /*
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+ * Tracking the NMI-blocked state in software is built upon
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+ * finding the next open IRQ window. This, in turn, depends on
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+ * well-behaving guests: They have to keep IRQs disabled at
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+ * least as long as the NMI handler runs. Otherwise we may
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+ * cause NMI nesting, maybe breaking the guest. But as this is
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+ * highly unlikely, we can live with the residual risk.
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+ */
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+ vmx->loaded_vmcs->soft_vnmi_blocked = 1;
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+ vmx->loaded_vmcs->vnmi_blocked_time = 0;
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+ }
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+
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++vcpu->stat.nmi_injections;
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vmx->loaded_vmcs->nmi_known_unmasked = false;
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@@ -5607,6 +5625,8 @@ static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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bool masked;
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+ if (!cpu_has_virtual_nmis())
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+ return vmx->loaded_vmcs->soft_vnmi_blocked;
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if (vmx->loaded_vmcs->nmi_known_unmasked)
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return false;
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masked = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_NMI;
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@@ -5618,13 +5638,20 @@ static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
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{
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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- vmx->loaded_vmcs->nmi_known_unmasked = !masked;
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- if (masked)
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- vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
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- GUEST_INTR_STATE_NMI);
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- else
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- vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
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- GUEST_INTR_STATE_NMI);
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+ if (!cpu_has_virtual_nmis()) {
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+ if (vmx->loaded_vmcs->soft_vnmi_blocked != masked) {
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+ vmx->loaded_vmcs->soft_vnmi_blocked = masked;
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+ vmx->loaded_vmcs->vnmi_blocked_time = 0;
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+ }
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+ } else {
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+ vmx->loaded_vmcs->nmi_known_unmasked = !masked;
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+ if (masked)
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+ vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
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+ GUEST_INTR_STATE_NMI);
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+ else
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+ vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
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+ GUEST_INTR_STATE_NMI);
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+ }
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}
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static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
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@@ -5632,6 +5659,10 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
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if (to_vmx(vcpu)->nested.nested_run_pending)
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return 0;
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+ if (!cpu_has_virtual_nmis() &&
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+ to_vmx(vcpu)->loaded_vmcs->soft_vnmi_blocked)
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+ return 0;
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+
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return !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
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(GUEST_INTR_STATE_MOV_SS | GUEST_INTR_STATE_STI
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| GUEST_INTR_STATE_NMI));
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@@ -6360,6 +6391,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
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* AAK134, BY25.
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*/
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if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
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+ cpu_has_virtual_nmis() &&
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(exit_qualification & INTR_INFO_UNBLOCK_NMI))
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vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
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@@ -6834,7 +6866,7 @@ static struct loaded_vmcs *nested_get_current_vmcs02(struct vcpu_vmx *vmx)
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}
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/* Create a new VMCS */
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- item = kmalloc(sizeof(struct vmcs02_list), GFP_KERNEL);
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+ item = kzalloc(sizeof(struct vmcs02_list), GFP_KERNEL);
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if (!item)
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return NULL;
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item->vmcs02.vmcs = alloc_vmcs();
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@@ -7851,6 +7883,7 @@ static int handle_pml_full(struct kvm_vcpu *vcpu)
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* "blocked by NMI" bit has to be set before next VM entry.
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*/
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if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
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+ cpu_has_virtual_nmis() &&
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(exit_qualification & INTR_INFO_UNBLOCK_NMI))
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vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
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GUEST_INTR_STATE_NMI);
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@@ -8568,6 +8601,25 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
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return 0;
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}
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+ if (unlikely(!cpu_has_virtual_nmis() &&
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+ vmx->loaded_vmcs->soft_vnmi_blocked)) {
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+ if (vmx_interrupt_allowed(vcpu)) {
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+ vmx->loaded_vmcs->soft_vnmi_blocked = 0;
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+ } else if (vmx->loaded_vmcs->vnmi_blocked_time > 1000000000LL &&
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+ vcpu->arch.nmi_pending) {
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+ /*
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+ * This CPU don't support us in finding the end of an
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+ * NMI-blocked window if the guest runs with IRQs
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+ * disabled. So we pull the trigger after 1 s of
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+ * futile waiting, but inform the user about this.
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+ */
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+ printk(KERN_WARNING "%s: Breaking out of NMI-blocked "
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+ "state on VCPU %d after 1 s timeout\n",
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+ __func__, vcpu->vcpu_id);
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+ vmx->loaded_vmcs->soft_vnmi_blocked = 0;
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+ }
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+ }
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+
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if (exit_reason < kvm_vmx_max_exit_handlers
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&& kvm_vmx_exit_handlers[exit_reason])
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return kvm_vmx_exit_handlers[exit_reason](vcpu);
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@@ -8850,33 +8902,38 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
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idtv_info_valid = vmx->idt_vectoring_info & VECTORING_INFO_VALID_MASK;
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- if (vmx->loaded_vmcs->nmi_known_unmasked)
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- return;
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- /*
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- * Can't use vmx->exit_intr_info since we're not sure what
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- * the exit reason is.
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- */
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- exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
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- unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0;
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- vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
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- /*
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- * SDM 3: 27.7.1.2 (September 2008)
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- * Re-set bit "block by NMI" before VM entry if vmexit caused by
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- * a guest IRET fault.
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- * SDM 3: 23.2.2 (September 2008)
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- * Bit 12 is undefined in any of the following cases:
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- * If the VM exit sets the valid bit in the IDT-vectoring
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- * information field.
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- * If the VM exit is due to a double fault.
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- */
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- if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi &&
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- vector != DF_VECTOR && !idtv_info_valid)
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- vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
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- GUEST_INTR_STATE_NMI);
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- else
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- vmx->loaded_vmcs->nmi_known_unmasked =
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- !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO)
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- & GUEST_INTR_STATE_NMI);
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+ if (cpu_has_virtual_nmis()) {
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+ if (vmx->loaded_vmcs->nmi_known_unmasked)
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+ return;
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+ /*
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+ * Can't use vmx->exit_intr_info since we're not sure what
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+ * the exit reason is.
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+ */
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+ exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
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+ unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0;
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+ vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
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+ /*
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+ * SDM 3: 27.7.1.2 (September 2008)
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+ * Re-set bit "block by NMI" before VM entry if vmexit caused by
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+ * a guest IRET fault.
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+ * SDM 3: 23.2.2 (September 2008)
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+ * Bit 12 is undefined in any of the following cases:
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+ * If the VM exit sets the valid bit in the IDT-vectoring
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+ * information field.
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+ * If the VM exit is due to a double fault.
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+ */
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+ if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi &&
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+ vector != DF_VECTOR && !idtv_info_valid)
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+ vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
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+ GUEST_INTR_STATE_NMI);
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+ else
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+ vmx->loaded_vmcs->nmi_known_unmasked =
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+ !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO)
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+ & GUEST_INTR_STATE_NMI);
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+ } else if (unlikely(vmx->loaded_vmcs->soft_vnmi_blocked))
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+ vmx->loaded_vmcs->vnmi_blocked_time +=
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+ ktime_to_ns(ktime_sub(ktime_get(),
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+ vmx->loaded_vmcs->entry_time));
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}
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static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
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@@ -8993,6 +9050,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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unsigned long debugctlmsr, cr3, cr4;
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+ /* Record the guest's net vcpu time for enforced NMI injections. */
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+ if (unlikely(!cpu_has_virtual_nmis() &&
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+ vmx->loaded_vmcs->soft_vnmi_blocked))
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+ vmx->loaded_vmcs->entry_time = ktime_get();
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+
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/* Don't enter VMX if guest state is invalid, let the exit handler
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start emulation until we arrive back to a valid state */
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if (vmx->emulation_required)
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--
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2.14.2
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