This patch contains the following two changes:
1. Fix the bug in nested preemption timer support. If vmexit L2->L0
with some reasons not emulated by L1, preemption timer value should
be save in such exits.
2. Add support of "Save VMX-preemption timer value" VM-Exit controls
to nVMX.
With this patch, nested VMX preemption timer features are fully
supported.
Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
---
ChangeLog to v4:
Format changes and remove a flag in nested_vmx.
arch/x86/include/uapi/asm/msr-index.h | 1 +
arch/x86/kvm/vmx.c | 44 +++++++++++++++++++++++++++++++--
2 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index bb04650..b93e09a 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -536,6 +536,7 @@
/* MSR_IA32_VMX_MISC bits */
#define MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS (1ULL << 29)
+#define MSR_IA32_VMX_MISC_PREEMPTION_TIMER_SCALE 0x1F
/* AMD-V MSRs */
#define MSR_VM_CR 0xc0010114
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1f1da43..e1fa13a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2204,7 +2204,13 @@ static __init void nested_vmx_setup_ctls_msrs(void)
#ifdef CONFIG_X86_64
VM_EXIT_HOST_ADDR_SPACE_SIZE |
#endif
- VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT;
+ VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT |
+ VM_EXIT_SAVE_VMX_PREEMPTION_TIMER;
+ if (!(nested_vmx_pinbased_ctls_high & PIN_BASED_VMX_PREEMPTION_TIMER) ||
+ !(nested_vmx_exit_ctls_high & VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)) {
+ nested_vmx_exit_ctls_high &= ~VM_EXIT_SAVE_VMX_PREEMPTION_TIMER;
+ nested_vmx_pinbased_ctls_high &= ~PIN_BASED_VMX_PREEMPTION_TIMER;
+ }
nested_vmx_exit_ctls_high |= (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
VM_EXIT_LOAD_IA32_EFER);
@@ -6707,6 +6713,27 @@ static void vmx_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2)
*info2 = vmcs_read32(VM_EXIT_INTR_INFO);
}
+static void nested_adjust_preemption_timer(struct kvm_vcpu *vcpu)
+{
+ u64 delta_tsc_l1;
+ u32 preempt_val_l1, preempt_val_l2, preempt_scale;
+
+ if (!(get_vmcs12(vcpu)->pin_based_vm_exec_control &
+ PIN_BASED_VMX_PREEMPTION_TIMER))
+ return;
+ preempt_scale = native_read_msr(MSR_IA32_VMX_MISC) &
+ MSR_IA32_VMX_MISC_PREEMPTION_TIMER_SCALE;
+ preempt_val_l2 = vmcs_read32(VMX_PREEMPTION_TIMER_VALUE);
+ delta_tsc_l1 = vmx_read_l1_tsc(vcpu, native_read_tsc())
+ - vcpu->arch.last_guest_tsc;
+ preempt_val_l1 = delta_tsc_l1 >> preempt_scale;
+ if (preempt_val_l2 <= preempt_val_l1)
+ preempt_val_l2 = 0;
+ else
+ preempt_val_l2 -= preempt_val_l1;
+ vmcs_write32(VMX_PREEMPTION_TIMER_VALUE, preempt_val_l2);
+}
+
/*
* The guest has exited. See if we can fix it or if we need userspace
* assistance.
@@ -7131,6 +7158,8 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
atomic_switch_perf_msrs(vmx);
debugctlmsr = get_debugctlmsr();
+ if (is_guest_mode(vcpu) && !(vmx->nested.nested_run_pending))
+ nested_adjust_preemption_timer(vcpu);
vmx->__launched = vmx->loaded_vmcs->launched;
asm(
/* Store host registers */
@@ -7518,6 +7547,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 exec_control;
+ u32 exit_control;
vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector);
vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector);
@@ -7691,7 +7721,10 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
* we should use its exit controls. Note that VM_EXIT_LOAD_IA32_EFER
* bits are further modified by vmx_set_efer() below.
*/
- vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
+ exit_control = vmcs_config.vmexit_ctrl;
+ if (vmcs12->pin_based_vm_exec_control & PIN_BASED_VMX_PREEMPTION_TIMER)
+ exit_control |= VM_EXIT_SAVE_VMX_PREEMPTION_TIMER;
+ vmcs_write32(VM_EXIT_CONTROLS, exit_control);
/* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE are
* emulated by vmx_set_efer(), below.
@@ -8090,6 +8123,13 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
vmcs12->guest_pending_dbg_exceptions =
vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
+ if ((vmcs12->pin_based_vm_exec_control &
+ PIN_BASED_VMX_PREEMPTION_TIMER) &&
+ (vmcs12->vm_exit_controls &
+ VM_EXIT_SAVE_VMX_PREEMPTION_TIMER))
+ vmcs12->vmx_preemption_timer_value =
+ vmcs_read32(VMX_PREEMPTION_TIMER_VALUE);
+
/*
* In some cases (usually, nested EPT), L2 is allowed to change its
* own CR3 without exiting. If it has changed it, we must keep it.
--
1.7.9.5
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