KVM: nVMX: Add preemption timer support

Provided the host has this feature, it's straightforward to offer it to
the guest as well. We just need to load to timer value on L2 entry if
the feature was enabled by L1 and watch out for the corresponding exit
reason.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 056bda586a453b100f59a793b89936a8bcd57a29..fc1c3134473b33a7087ff262876fc3f5b6d83759 100644 (file)
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -70,6 +70,7 @@
 #define PIN_BASED_EXT_INTR_MASK                 0x00000001
 #define PIN_BASED_NMI_EXITING                   0x00000008
 #define PIN_BASED_VIRTUAL_NMIS                  0x00000020
+#define PIN_BASED_VMX_PREEMPTION_TIMER          0x00000040
 
 #define PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR    0x00000016
 
@@ -95,6 +96,7 @@
 
 #define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR     0x000011ff
 
+#define VMX_MISC_PREEMPTION_TIMER_RATE_MASK    0x0000001f
 #define VMX_MISC_SAVE_EFER_LMA                 0x00000020
 
 /* VMCS Encodings */
@@ -217,6 +219,7 @@ enum vmcs_field {
        GUEST_INTERRUPTIBILITY_INFO     = 0x00004824,
        GUEST_ACTIVITY_STATE            = 0X00004826,
        GUEST_SYSENTER_CS               = 0x0000482A,
+       VMX_PREEMPTION_TIMER_VALUE      = 0x0000482E,
        HOST_IA32_SYSENTER_CS           = 0x00004c00,
        CR0_GUEST_HOST_MASK             = 0x00006000,
        CR4_GUEST_HOST_MASK             = 0x00006002,

diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index 2871fccfee68619896f03d50ab4b93f75eaad8e3..d651082c7cf720a805f653b162343f6b9a984329 100644 (file)
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -65,6 +65,7 @@
 #define EXIT_REASON_EOI_INDUCED         45
 #define EXIT_REASON_EPT_VIOLATION       48
 #define EXIT_REASON_EPT_MISCONFIG       49
+#define EXIT_REASON_PREEMPTION_TIMER    52
 #define EXIT_REASON_WBINVD              54
 #define EXIT_REASON_XSETBV              55
 #define EXIT_REASON_APIC_WRITE          56
@@ -110,7 +111,7 @@
        { EXIT_REASON_EOI_INDUCED,           "EOI_INDUCED" }, \
        { EXIT_REASON_INVALID_STATE,         "INVALID_STATE" }, \
        { EXIT_REASON_INVD,                  "INVD" }, \
-       { EXIT_REASON_INVPCID,               "INVPCID" }
-
+       { EXIT_REASON_INVPCID,               "INVPCID" }, \
+       { EXIT_REASON_PREEMPTION_TIMER,      "PREEMPTION_TIMER" }
 
 #endif /* _UAPIVMX_H */

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 02f8c32b9b086189c72bf6fca58b33b1d16b970f..17a693868458c46d7bc1de5b5c8c368275077f54 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -298,7 +298,8 @@ struct __packed vmcs12 {
        u32 guest_activity_state;
        u32 guest_sysenter_cs;
        u32 host_ia32_sysenter_cs;
-       u32 padding32[8]; /* room for future expansion */
+       u32 vmx_preemption_timer_value;
+       u32 padding32[7]; /* room for future expansion */
        u16 virtual_processor_id;
        u16 guest_es_selector;
        u16 guest_cs_selector;
@@ -537,6 +538,7 @@ static const unsigned short vmcs_field_to_offset_table[] = {
        FIELD(GUEST_ACTIVITY_STATE, guest_activity_state),
        FIELD(GUEST_SYSENTER_CS, guest_sysenter_cs),
        FIELD(HOST_IA32_SYSENTER_CS, host_ia32_sysenter_cs),
+       FIELD(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value),
        FIELD(CR0_GUEST_HOST_MASK, cr0_guest_host_mask),
        FIELD(CR4_GUEST_HOST_MASK, cr4_guest_host_mask),
        FIELD(CR0_READ_SHADOW, cr0_read_shadow),
@@ -2049,7 +2051,8 @@ static __init void nested_vmx_setup_ctls_msrs(void)
         */
        nested_vmx_pinbased_ctls_low |= PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR;
        nested_vmx_pinbased_ctls_high &= PIN_BASED_EXT_INTR_MASK |
-               PIN_BASED_NMI_EXITING | PIN_BASED_VIRTUAL_NMIS;
+               PIN_BASED_NMI_EXITING | PIN_BASED_VIRTUAL_NMIS |
+               PIN_BASED_VMX_PREEMPTION_TIMER;
        nested_vmx_pinbased_ctls_high |= PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR;
 
        /*
@@ -2110,7 +2113,8 @@ static __init void nested_vmx_setup_ctls_msrs(void)
 
        /* miscellaneous data */
        rdmsr(MSR_IA32_VMX_MISC, nested_vmx_misc_low, nested_vmx_misc_high);
-       nested_vmx_misc_low &= VMX_MISC_SAVE_EFER_LMA;
+       nested_vmx_misc_low &= VMX_MISC_PREEMPTION_TIMER_RATE_MASK |
+               VMX_MISC_SAVE_EFER_LMA;
        nested_vmx_misc_high = 0;
 }
 
@@ -6190,6 +6194,9 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
        case EXIT_REASON_EPT_VIOLATION:
        case EXIT_REASON_EPT_MISCONFIG:
                return 0;
+       case EXIT_REASON_PREEMPTION_TIMER:
+               return vmcs12->pin_based_vm_exec_control &
+                       PIN_BASED_VMX_PREEMPTION_TIMER;
        case EXIT_REASON_WBINVD:
                return nested_cpu_has2(vmcs12, SECONDARY_EXEC_WBINVD_EXITING);
        case EXIT_REASON_XSETBV:
@@ -7011,6 +7018,10 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
                (vmcs_config.pin_based_exec_ctrl |
                 vmcs12->pin_based_vm_exec_control));
 
+       if (vmcs12->pin_based_vm_exec_control & PIN_BASED_VMX_PREEMPTION_TIMER)
+               vmcs_write32(VMX_PREEMPTION_TIMER_VALUE,
+                            vmcs12->vmx_preemption_timer_value);
+
        /*
         * Whether page-faults are trapped is determined by a combination of
         * 3 settings: PFEC_MASK, PFEC_MATCH and EXCEPTION_BITMAP.PF.