[PATCH 2/2] KVM: x86: introduce lapic_in_kernel

From: Paolo Bonzini
Date: Thu Jul 30 2015 - 07:27:36 EST

Avoid pointer chasing and memory barriers, and simplify the code
when split irqchip (LAPIC in kernel, IOAPIC/PIC in userspace)
is introduced.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/irq.c | 6 +++---
arch/x86/kvm/irq.h | 8 ++++++++
arch/x86/kvm/lapic.c | 4 ++--
arch/x86/kvm/mmu.c | 2 +-
arch/x86/kvm/svm.c | 4 ++--
arch/x86/kvm/vmx.c | 46 ++++++++++++++++++++--------------------------
arch/x86/kvm/x86.c | 18 +++++++++---------
7 files changed, 45 insertions(+), 43 deletions(-)

diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index c0dad893dc59..b653ae202c8e 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -57,7 +57,7 @@ static int kvm_cpu_has_extint(struct kvm_vcpu *v)
*/
int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
{
- if (!irqchip_in_kernel(v->kvm))
+ if (!lapic_in_kernel(v))
return v->arch.interrupt.pending;

if (kvm_cpu_has_extint(v))
@@ -75,7 +75,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
*/
int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
{
- if (!irqchip_in_kernel(v->kvm))
+ if (!lapic_in_kernel(v))
return v->arch.interrupt.pending;

if (kvm_cpu_has_extint(v))
@@ -103,7 +103,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
{
int vector;

- if (!irqchip_in_kernel(v->kvm))
+ if (!lapic_in_kernel(v))
return v->arch.interrupt.nr;

vector = kvm_cpu_get_extint(v);
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 3d782a2c336a..9e6e7e04de98 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -92,6 +92,14 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
return vpic != NULL;
}

+static inline int lapic_in_kernel(struct kvm_vcpu *vcpu)
+{
+ /* Same as irqchip_in_kernel(vcpu->kvm), but with less
+ * pointer chasing and no unnecessary memory barriers.
+ */
+ return vcpu->arch.apic != NULL;
+}
+
void kvm_pic_reset(struct kvm_kpic_state *s);

void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ab28cb40d51b..5cae917451f9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1984,7 +1984,7 @@ int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)
struct kvm_lapic *apic = vcpu->arch.apic;
u32 reg = (msr - APIC_BASE_MSR) << 4;

- if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
+ if (!lapic_in_kernel(vcpu) || !apic_x2apic_mode(apic))
return 1;

if (reg == APIC_ICR2)
@@ -2001,7 +2001,7 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
struct kvm_lapic *apic = vcpu->arch.apic;
u32 reg = (msr - APIC_BASE_MSR) << 4, low, high = 0;

- if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
+ if (!lapic_in_kernel(vcpu) || !apic_x2apic_mode(apic))
return 1;

if (reg == APIC_DFR || reg == APIC_ICR2) {
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 44171462bd2a..6de896fd0b78 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3421,7 +3421,7 @@ static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn)

static bool can_do_async_pf(struct kvm_vcpu *vcpu)
{
- if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
+ if (unlikely(!lapic_in_kernel(vcpu) ||
kvm_event_needs_reinjection(vcpu)))
return false;

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 194646383eea..4283bd0d2bc2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3151,7 +3151,7 @@ static int cr8_write_interception(struct vcpu_svm *svm)
u8 cr8_prev = kvm_get_cr8(&svm->vcpu);
/* instruction emulation calls kvm_set_cr8() */
r = cr_interception(svm);
- if (irqchip_in_kernel(svm->vcpu.kvm))
+ if (lapic_in_kernel(&svm->vcpu))
return r;
if (cr8_prev <= kvm_get_cr8(&svm->vcpu))
return r;
@@ -3406,7 +3406,7 @@ static int interrupt_window_interception(struct vcpu_svm *svm)
* If the user space waits to inject interrupts, exit as soon as
* possible
*/
- if (!irqchip_in_kernel(svm->vcpu.kvm) &&
+ if (!lapic_in_kernel(&svm->vcpu) &&
kvm_run->request_interrupt_window &&
!kvm_cpu_has_interrupt(&svm->vcpu)) {
kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 57a645b85145..7ede71374da8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -809,7 +809,6 @@ static void kvm_cpu_vmxon(u64 addr);
static void kvm_cpu_vmxoff(void);
static bool vmx_mpx_supported(void);
static bool vmx_xsaves_supported(void);
-static int vmx_vm_has_apicv(struct kvm *kvm);
static int vmx_cpu_uses_apicv(struct kvm_vcpu *vcpu);
static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
static void vmx_set_segment(struct kvm_vcpu *vcpu,
@@ -947,9 +946,9 @@ static inline bool cpu_has_vmx_tpr_shadow(void)
return vmcs_config.cpu_based_exec_ctrl & CPU_BASED_TPR_SHADOW;
}

-static inline bool vm_need_tpr_shadow(struct kvm *kvm)
+static inline bool cpu_need_tpr_shadow(struct kvm_vcpu *vcpu)
{
- return (cpu_has_vmx_tpr_shadow()) && (irqchip_in_kernel(kvm));
+ return cpu_has_vmx_tpr_shadow() && lapic_in_kernel(vcpu);
}

static inline bool cpu_has_secondary_exec_ctrls(void)
@@ -1063,9 +1062,9 @@ static inline bool cpu_has_vmx_ple(void)
SECONDARY_EXEC_PAUSE_LOOP_EXITING;
}

-static inline bool vm_need_virtualize_apic_accesses(struct kvm *kvm)
+static inline bool cpu_need_virtualize_apic_accesses(struct kvm_vcpu *vcpu)
{
- return flexpriority_enabled && irqchip_in_kernel(kvm);
+ return flexpriority_enabled && lapic_in_kernel(vcpu);
}

static inline bool cpu_has_vmx_vpid(void)
@@ -2378,7 +2377,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
vmx->nested.nested_vmx_pinbased_ctls_high |=
PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR |
PIN_BASED_VMX_PREEMPTION_TIMER;
- if (vmx_vm_has_apicv(vmx->vcpu.kvm))
+ if (vmx_cpu_uses_apicv(&vmx->vcpu))
vmx->nested.nested_vmx_pinbased_ctls_high |=
PIN_BASED_POSTED_INTR;

@@ -4333,14 +4332,9 @@ static void vmx_disable_intercept_msr_write_x2apic(u32 msr)
msr, MSR_TYPE_W);
}

-static int vmx_vm_has_apicv(struct kvm *kvm)
-{
- return enable_apicv && irqchip_in_kernel(kvm);
-}
-
static int vmx_cpu_uses_apicv(struct kvm_vcpu *vcpu)
{
- return vmx_vm_has_apicv(vcpu->kvm);
+ return enable_apicv && lapic_in_kernel(vcpu);
}

static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
@@ -4520,7 +4514,7 @@ static u32 vmx_pin_based_exec_ctrl(struct vcpu_vmx *vmx)
{
u32 pin_based_exec_ctrl = vmcs_config.pin_based_exec_ctrl;

- if (!vmx_vm_has_apicv(vmx->vcpu.kvm))
+ if (!vmx_cpu_uses_apicv(&vmx->vcpu))
pin_based_exec_ctrl &= ~PIN_BASED_POSTED_INTR;
return pin_based_exec_ctrl;
}
@@ -4532,7 +4526,7 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
if (vmx->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)
exec_control &= ~CPU_BASED_MOV_DR_EXITING;

- if (!vm_need_tpr_shadow(vmx->vcpu.kvm)) {
+ if (!cpu_need_tpr_shadow(&vmx->vcpu)) {
exec_control &= ~CPU_BASED_TPR_SHADOW;
#ifdef CONFIG_X86_64
exec_control |= CPU_BASED_CR8_STORE_EXITING |
@@ -4549,7 +4543,7 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
{
u32 exec_control = vmcs_config.cpu_based_2nd_exec_ctrl;
- if (!vm_need_virtualize_apic_accesses(vmx->vcpu.kvm))
+ if (!cpu_need_virtualize_apic_accesses(&vmx->vcpu))
exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
if (vmx->vpid == 0)
exec_control &= ~SECONDARY_EXEC_ENABLE_VPID;
@@ -4563,7 +4557,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
if (!ple_gap)
exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;
- if (!vmx_vm_has_apicv(vmx->vcpu.kvm))
+ if (!vmx_cpu_uses_apicv(&vmx->vcpu))
exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |
SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
@@ -4624,7 +4618,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmx_secondary_exec_control(vmx));
}

- if (vmx_vm_has_apicv(vmx->vcpu.kvm)) {
+ if (vmx_cpu_uses_apicv(&vmx->vcpu)) {
vmcs_write64(EOI_EXIT_BITMAP0, 0);
vmcs_write64(EOI_EXIT_BITMAP1, 0);
vmcs_write64(EOI_EXIT_BITMAP2, 0);
@@ -4768,7 +4762,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)

if (cpu_has_vmx_tpr_shadow() && !init_event) {
vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0);
- if (vm_need_tpr_shadow(vcpu->kvm))
+ if (cpu_need_tpr_shadow(vcpu))
vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
__pa(vcpu->arch.apic->regs));
vmcs_write32(TPR_THRESHOLD, 0);
@@ -4776,7 +4770,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)

kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu);

- if (vmx_vm_has_apicv(vcpu->kvm))
+ if (vmx_cpu_uses_apicv(vcpu))
memset(&vmx->pi_desc, 0, sizeof(struct pi_desc));

if (vmx->vpid != 0)
@@ -5316,7 +5310,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
u8 cr8 = (u8)val;
err = kvm_set_cr8(vcpu, cr8);
kvm_complete_insn_gp(vcpu, err);
- if (irqchip_in_kernel(vcpu->kvm))
+ if (lapic_in_kernel(vcpu))
return 1;
if (cr8_prev <= cr8)
return 1;
@@ -5535,7 +5529,7 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu)
* If the user space waits to inject interrupts, exit as soon as
* possible
*/
- if (!irqchip_in_kernel(vcpu->kvm) &&
+ if (!lapic_in_kernel(vcpu) &&
vcpu->run->request_interrupt_window &&
!kvm_cpu_has_interrupt(vcpu)) {
vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
@@ -8012,10 +8006,10 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
* apicv
*/
if (!cpu_has_vmx_virtualize_x2apic_mode() ||
- !vmx_vm_has_apicv(vcpu->kvm))
+ !vmx_cpu_uses_apicv(vcpu))
return;

- if (!vm_need_tpr_shadow(vcpu->kvm))
+ if (!cpu_need_tpr_shadow(vcpu))
return;

sec_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
@@ -8120,7 +8114,7 @@ static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu)
{
u64 *eoi_exit_bitmap = vcpu->arch.eoi_exit_bitmap;
- if (!vmx_vm_has_apicv(vcpu->kvm))
+ if (!vmx_cpu_uses_apicv(vcpu))
return;

vmcs_write64(EOI_EXIT_BITMAP0, eoi_exit_bitmap[0]);
@@ -8619,7 +8613,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
put_cpu();
if (err)
goto free_vmcs;
- if (vm_need_virtualize_apic_accesses(kvm)) {
+ if (cpu_need_virtualize_apic_accesses(&vmx->vcpu)) {
err = alloc_apic_access_page(kvm);
if (err)
goto free_vmcs;
@@ -9407,7 +9401,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
vmcs_write64(APIC_ACCESS_ADDR,
page_to_phys(vmx->nested.apic_access_page));
} else if (!(nested_cpu_has_virt_x2apic_mode(vmcs12)) &&
- (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm))) {
+ cpu_need_virtualize_apic_accesses(&vmx->vcpu)) {
exec_control |=
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
kvm_vcpu_reload_apic_access_page(vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4ad7334aa604..741e7c0bcd9d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -786,7 +786,7 @@ int kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
{
if (cr8 & CR8_RESERVED_BITS)
return 1;
- if (irqchip_in_kernel(vcpu->kvm))
+ if (lapic_in_kernel(vcpu))
kvm_lapic_set_tpr(vcpu, cr8);
else
vcpu->arch.cr8 = cr8;
@@ -796,7 +796,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cr8);

unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu)
{
- if (irqchip_in_kernel(vcpu->kvm))
+ if (lapic_in_kernel(vcpu))
return kvm_lapic_get_cr8(vcpu);
else
return vcpu->arch.cr8;
@@ -3187,7 +3187,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
struct kvm_vapic_addr va;

r = -EINVAL;
- if (!irqchip_in_kernel(vcpu->kvm))
+ if (!lapic_in_kernel(vcpu))
goto out;
r = -EFAULT;
if (copy_from_user(&va, argp, sizeof va))
@@ -5678,7 +5678,7 @@ void kvm_arch_exit(void)
int kvm_vcpu_halt(struct kvm_vcpu *vcpu)
{
++vcpu->stat.halt_exits;
- if (irqchip_in_kernel(vcpu->kvm)) {
+ if (lapic_in_kernel(vcpu)) {
vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
return 1;
} else {
@@ -6167,7 +6167,7 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
{
struct page *page = NULL;

- if (!irqchip_in_kernel(vcpu->kvm))
+ if (!lapic_in_kernel(vcpu))
return;

if (!kvm_x86_ops->set_apic_access_page_addr)
@@ -6205,7 +6205,7 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
{
int r;
- bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
+ bool req_int_win = !lapic_in_kernel(vcpu) &&
vcpu->run->request_interrupt_window;
bool req_immediate_exit = false;

@@ -6602,7 +6602,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
}

/* re-sync apic's tpr */
- if (!irqchip_in_kernel(vcpu->kvm)) {
+ if (!lapic_in_kernel(vcpu)) {
if (kvm_set_cr8(vcpu, kvm_run->cr8) != 0) {
r = -EINVAL;
goto out;
@@ -7302,7 +7302,7 @@ bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)

bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
{
- return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL);
+ return irqchip_in_kernel(vcpu->kvm) == lapic_in_kernel(vcpu);
}

struct static_key kvm_no_apic_vcpu __read_mostly;
@@ -7396,7 +7396,7 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
kvm_mmu_destroy(vcpu);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
free_page((unsigned long)vcpu->arch.pio_data);
- if (!irqchip_in_kernel(vcpu->kvm))
+ if (!lapic_in_kernel(vcpu))
static_key_slow_dec(&kvm_no_apic_vcpu);
}

--
1.8.3.1

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