Re: [PATCH v9 2/3] x86, apicv: add virtual x2apic support

Gleb Natapov
2013-01-11T13:51:26Z

On Fri, Jan 11, 2013 at 02:37:15AM +0000, Zhang, Yang Z wrote:
> Gleb Natapov wrote on 2013-01-10:
> > On Thu, Jan 10, 2013 at 08:32:06AM +0000, Zhang, Yang Z wrote:
> >> Gleb Natapov wrote on 2013-01-10:
> >>> On Thu, Jan 10, 2013 at 03:26:07PM +0800, Yang Zhang wrote:
> >>>> From: Yang Zhang <yang.z.zhang@Intel.com>
> >>>>
> >>>> basically to benefit from apicv, we need to enable virtualized x2apic mode.
> >>>> Currently, we only enable it when guest is really using x2apic.
> >>>>
> >>>> Also, clear MSR bitmap for corresponding x2apic MSRs when guest enabled
> >>> x2apic:
> >>>> 0x800 - 0x8ff: no read intercept for apicv register virtualization,
> >>>> except APIC ID and TMCCT.
> >>>> APIC ID and TMCCT: need software's assistance to get right value.
> >>>> TPR,EOI,SELF-IPI: no write intercept for virtual interrupt delivery.
> >>>> Signed-off-by: Kevin Tian <kevin.tian@intel.com>
> >>>> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> >>>> ---
> >>>> arch/x86/include/asm/kvm_host.h | 2 + arch/x86/include/asm/vmx.h
> >>>> | 1 + arch/x86/kvm/lapic.c | 5 +-
> >>>> arch/x86/kvm/svm.c | 6 + arch/x86/kvm/vmx.c | 194
> >>>> +++++++++++++++++++++++++++++++++++++-- 5 files
> > changed, 200
> >>>> insertions(+), 8 deletions(-)
> >>>> diff --git a/arch/x86/include/asm/kvm_host.h
> >>>> b/arch/x86/include/asm/kvm_host.h index c431b33..572a562 100644 ---
> >>>> a/arch/x86/include/asm/kvm_host.h +++
> >>>> b/arch/x86/include/asm/kvm_host.h @@ -697,6 +697,8 @@ struct
> >>>> kvm_x86_ops {
> >>>> void (*enable_nmi_window)(struct kvm_vcpu *vcpu);
> >>>> void (*enable_irq_window)(struct kvm_vcpu *vcpu);
> >>>> void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);
> >>>> + void (*enable_virtual_x2apic_mode)(struct kvm_vcpu *vcpu);
> >>>> + void (*disable_virtual_x2apic_mode)(struct kvm_vcpu *vcpu);
> >>> Make one callback with enable/disable parameter. And do not forget SVM.
> >>>
> >>>> int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
> >>>> int (*get_tdp_level)(void);
> >>>> u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool
> > is_mmio);
> >>>> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> >>>> index 44c3f7e..0a54df0 100644
> >>>> --- a/arch/x86/include/asm/vmx.h
> >>>> +++ b/arch/x86/include/asm/vmx.h
> >>>> @@ -139,6 +139,7 @@
> >>>> #define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001 #define
> >>>> SECONDARY_EXEC_ENABLE_EPT 0x00000002 #define
> >>>> SECONDARY_EXEC_RDTSCP 0x00000008 +#define
> >>>> SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE 0x00000010 #define
> >>>> SECONDARY_EXEC_ENABLE_VPID 0x00000020 #define
> >>>> SECONDARY_EXEC_WBINVD_EXITING 0x00000040 #define
> >>>> SECONDARY_EXEC_UNRESTRICTED_GUEST 0x00000080
> >>>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> >>>> index 0664c13..ec38906 100644
> >>>> --- a/arch/x86/kvm/lapic.c
> >>>> +++ b/arch/x86/kvm/lapic.c
> >>>> @@ -1328,7 +1328,10 @@ void kvm_lapic_set_base(struct kvm_vcpu
> > *vcpu,
> >>> u64 value)
> >>>> u32 id = kvm_apic_id(apic);
> >>>> u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
> >>>> kvm_apic_set_ldr(apic, ldr);
> >>>> - }
> >>>> + kvm_x86_ops->enable_virtual_x2apic_mode(vcpu);
> >>>> + } else
> >>>> + kvm_x86_ops->disable_virtual_x2apic_mode(vcpu);
> >>>> +
> >>> You just broke SVM.
> >>>> apic->base_address = apic->vcpu->arch.apic_base &
> >>>> MSR_IA32_APICBASE_BASE;
> >>>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> >>>> index d29d3cd..0b82cb1 100644
> >>>> --- a/arch/x86/kvm/svm.c
> >>>> +++ b/arch/x86/kvm/svm.c
> >>>> @@ -3571,6 +3571,11 @@ static void update_cr8_intercept(struct
> > kvm_vcpu
> >>> *vcpu, int tpr, int irr)
> >>>> set_cr_intercept(svm, INTERCEPT_CR8_WRITE);
> >>>> }
> >>>> +static void svm_enable_virtual_x2apic_mode(struct kvm_vcpu *vcpu)
> >>>> +{
> >>>> + return;
> >>>> +}
> >>>> +
> >>>> static int svm_nmi_allowed(struct kvm_vcpu *vcpu) { struct vcpu_svm
> >>>> *svm = to_svm(vcpu); @@ -4290,6 +4295,7 @@ static struct kvm_x86_ops
> >>>> svm_x86_ops = { .enable_nmi_window = enable_nmi_window,
> >>>> .enable_irq_window = enable_irq_window, .update_cr8_intercept =
> >>>> update_cr8_intercept,
> >>>> + .enable_virtual_x2apic_mode = svm_enable_virtual_x2apic_mode,
> >>>>
> >>>> .set_tss_addr = svm_set_tss_addr,
> >>>> .get_tdp_level = get_npt_level,
> >>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> >>>> index 688f43f..b203ce7 100644
> >>>> --- a/arch/x86/kvm/vmx.c
> >>>> +++ b/arch/x86/kvm/vmx.c
> >>>> @@ -433,6 +433,8 @@ struct vcpu_vmx {
> >>>>
> >>>> bool rdtscp_enabled;
> >>>> + bool virtual_x2apic_enabled;
> >>>> +
> >>>> /* Support for a guest hypervisor (nested VMX) */
> >>>> struct nested_vmx nested;
> >>>> };
> >>>> @@ -767,12 +769,23 @@ static inline bool
> >>> cpu_has_vmx_virtualize_apic_accesses(void)
> >>>> SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
> >>>> }
> >>>> +static inline bool cpu_has_vmx_virtualize_x2apic_mode(void)
> >>>> +{
> >>>> + return vmcs_config.cpu_based_2nd_exec_ctrl &
> >>>> + SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
> >>>> +}
> >>>> +
> >>>> static inline bool cpu_has_vmx_apic_register_virt(void)
> >>>> {
> >>>> return vmcs_config.cpu_based_2nd_exec_ctrl &
> >>>> SECONDARY_EXEC_APIC_REGISTER_VIRT;
> >>>> }
> >>>> +static inline bool cpu_has_vmx_virtual_intr_delivery(void)
> >>>> +{
> >>>> + return false;
> >>>> +}
> >>>> +
> >>>> static inline bool cpu_has_vmx_flexpriority(void)
> >>>> {
> >>>> return cpu_has_vmx_tpr_shadow() &&
> >>>> @@ -2544,6 +2557,7 @@ static __init int setup_vmcs_config(struct
> >>> vmcs_config *vmcs_conf)
> >>>> if (_cpu_based_exec_control &
> >>>> CPU_BASED_ACTIVATE_SECONDARY_CONTROLS) { min2 = 0; opt2 =
> >>>> SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
> >>>> + SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
> >>>> SECONDARY_EXEC_WBINVD_EXITING | SECONDARY_EXEC_ENABLE_VPID |
> >>>> SECONDARY_EXEC_ENABLE_EPT | @@ -3731,7 +3745,45 @@ static void
> >>>> free_vpid(struct vcpu_vmx *vmx) spin_unlock(&vmx_vpid_lock); }
> >>>> -static void __vmx_disable_intercept_for_msr(unsigned long
> >>>> *msr_bitmap, u32 msr) +#define MSR_TYPE_R 1 +#define MSR_TYPE_W 2
> >>>> +static void __vmx_disable_intercept_for_msr(unsigned long
> >>>> *msr_bitmap, + u32 msr, int type) +{ + int f = sizeof(unsigned
> >>>> long); + + if (!cpu_has_vmx_msr_bitmap()) + return; + + /* + * See
> >>>> Intel PRM Vol. 3, 20.6.9 (MSR-Bitmap Address). Early manuals + *
> >>>> have the write-low and read-high bitmap offsets the wrong way round.
> >>>> + * We can control MSRs 0x00000000-0x00001fff and
> >>>> 0xc0000000-0xc0001fff. + */ + if (msr <= 0x1fff) { + if (type &
> >>>> MSR_TYPE_R) + /* read-low */ + __clear_bit(msr, msr_bitmap +
> >>>> 0x000 / f); + + if (type & MSR_TYPE_W) + /* write-low */ +
> >>>> __clear_bit(msr, msr_bitmap + 0x800 / f); + + } else if ((msr >=
> >>>> 0xc0000000) && (msr <= 0xc0001fff)) { + msr &= 0x1fff; + if (type &
> >>>> MSR_TYPE_R) + /* read-high */ + __clear_bit(msr, msr_bitmap +
> >>>> 0x400 / f); + + if (type & MSR_TYPE_W) + /* write-high */ +
> >>>> __clear_bit(msr, msr_bitmap + 0xc00 / f); + + } +} + +static void
> >>>> __vmx_enable_intercept_for_msr(unsigned long *msr_bitmap, + u32
> >>>> msr, int type)
> >>>> {
> >>>> int f = sizeof(unsigned long);
> >>>> @@ -3744,20 +3796,75 @@ static void
> >>> __vmx_disable_intercept_for_msr(unsigned long *msr_bitmap, u32 msr)
> >>>> * We can control MSRs 0x00000000-0x00001fff and
> >>>> 0xc0000000-0xc0001fff. */ if (msr <= 0x1fff) {
> >>>> - __clear_bit(msr, msr_bitmap + 0x000 / f); /* read-low */
> >>>> - __clear_bit(msr, msr_bitmap + 0x800 / f); /* write-low */
> >>>> + if (type & MSR_TYPE_R)
> >>>> + /* read-low */
> >>>> + __set_bit(msr, msr_bitmap + 0x000 / f);
> >>>> +
> >>>> + if (type & MSR_TYPE_W)
> >>>> + /* write-low */
> >>>> + __set_bit(msr, msr_bitmap + 0x800 / f);
> >>>> +
> >>>> } else if ((msr >= 0xc0000000) && (msr <= 0xc0001fff)) {
> >>>> msr &= 0x1fff;
> >>>> - __clear_bit(msr, msr_bitmap + 0x400 / f); /* read-high */
> >>>> - __clear_bit(msr, msr_bitmap + 0xc00 / f); /* write-high */
> >>>> + if (type & MSR_TYPE_R)
> >>>> + /* read-high */
> >>>> + __set_bit(msr, msr_bitmap + 0x400 / f);
> >>>> +
> >>>> + if (type & MSR_TYPE_W)
> >>>> + /* write-high */
> >>>> + __set_bit(msr, msr_bitmap + 0xc00 / f);
> >>>> +
> >>>> } } + static void vmx_disable_intercept_for_msr(u32 msr, bool
> >>>> longmode_only) { if (!longmode_only)
> >>>> - __vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, msr);
> >>>> - __vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, msr);
> >>>> + __vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, + msr,
> >>>> MSR_TYPE_R | MSR_TYPE_W);
> >>>> + __vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode,
> >>>> + msr, MSR_TYPE_R | MSR_TYPE_W); +} + +static void
> >>>> vmx_intercept_for_msr_read(u32 msr, bool longmode_only, + bool
> >>>> set) +{ + if (!longmode_only) { + if (set) +
> >>>> __vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy, + msr,
> >>>> MSR_TYPE_R); + else +
> >>>> __vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, + msr,
> >>>> MSR_TYPE_R); + + } + if (set)
> >>>> + __vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode, + msr,
> >>>> MSR_TYPE_R); + else
> >>>> + __vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, + msr,
> >>>> MSR_TYPE_R); +} + +static void vmx_intercept_for_msr_write(u32 msr,
> >>>> bool longmode_only, + bool set) +{ + if (!longmode_only) { + if
> >>>> (set) + __vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy,
> >>>> + msr, MSR_TYPE_W); + else +
> >>>> __vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, + msr,
> >>>> MSR_TYPE_W); + + } + if (set)
> >>>> + __vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode, + msr,
> >>>> MSR_TYPE_W); + else
> >>>> + __vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, + msr,
> >>>> MSR_TYPE_W);
> >>>> }
> >>>>
> >>>> /*
> >>>> @@ -3855,6 +3962,7 @@ static u32 vmx_secondary_exec_control(struct
> >>> vcpu_vmx *vmx)
> >>>> exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING; if
> >>>> (!enable_apicv_reg_vid) exec_control &=
> >>>> ~SECONDARY_EXEC_APIC_REGISTER_VIRT; + exec_control &=
> >>>> ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE; return
> > exec_control; }
> >>>> @@ -6110,6 +6218,76 @@ static void update_cr8_intercept(struct
> > kvm_vcpu
> >>> *vcpu, int tpr, int irr)
> >>>> vmcs_write32(TPR_THRESHOLD, irr);
> >>>> }
> >>>> +static void vmx_enable_virtual_x2apic_mode(struct kvm_vcpu *vcpu)
> >>>> +{
> >>>> + u32 exec_control;
> >>>> + int msr;
> >>>> + struct vcpu_vmx *vmx = to_vmx(vcpu);
> >>>> +
> >>>> + if (!cpu_has_vmx_virtualize_x2apic_mode())
> >>>> + return;
> >>>> +
> >>>> + exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> >>>> + /* virtualize x2apic mode relies on tpr shadow */
> >>>> + if (!(exec_control & CPU_BASED_TPR_SHADOW))
> >>>> + return;
> >>>> +
> >>>> + exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> >>>> + exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
> >>>> + exec_control |= SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
> >>>> + vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
> >>>> + vmx->virtual_x2apic_enabled = true;
> >>> Why track it?
> >> With this flag, we don't need to read vmcs to check whether we enabled
> >> virtua x2apic before.
> >>
> > Why do you care? Just disabled it regardless.
> kvm_lapic_set_base will be called when creating lapic. At that time, vcpu didn't initialized. Then read/write vmcs in vmx_disable_virtual_x2apic_mode will cause error.
> With this flag, we only disable the virtual x2apic mode if it is enabled before.
>
Then call vmx_enable_virtual_x2apic_mode() only when mode actually changes.
kvm_lapic_set_base() can track it like it does to MSR_IA32_APICBASE_ENABLE.

--
Gleb.