[PATCH 5/6] KVM: x86: do not scan IRR twice on APICv vmentry

Paolo Bonzini
2016-12-19T16:17:49Z

Calls to apic_find_highest_irr are scanning IRR twice, once
in vmx_sync_pir_from_irr and once in apic_search_irr. Change
sync_pir_from_irr to get the new maximum IRR from kvm_apic_update_irr;
now that it does the computation, it can also do the RVI write.

In order to avoid complications in svm.c, make the callback optional.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/lapic.c | 8 +++++---
arch/x86/kvm/svm.c | 6 ------
arch/x86/kvm/vmx.c | 30 ++++++++++++++++++------------
arch/x86/kvm/x86.c | 7 ++-----
5 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4b820b2b6bfa..b182b0ee0997 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -965,7 +965,7 @@ struct kvm_x86_ops {
void (*set_virtual_x2apic_mode)(struct kvm_vcpu *vcpu, bool set);
void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu, hpa_t hpa);
void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
- void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
+ int (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
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/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 4af0e105caad..f644dd1dbe71 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -515,6 +515,7 @@ int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu)
*/
return apic_find_highest_irr(vcpu->arch.apic);
}
+EXPORT_SYMBOL_GPL(kvm_lapic_find_highest_irr);

static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
int vector, int level, int trig_mode,
@@ -580,9 +581,10 @@ static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu)
static int apic_has_interrupt_for_ppr(struct kvm_lapic *apic, u32 ppr)
{
int highest_irr;
- if (apic->vcpu->arch.apicv_active)
- kvm_x86_ops->sync_pir_to_irr(apic->vcpu);
- highest_irr = apic_find_highest_irr(apic);
+ if (kvm_x86_ops->sync_pir_to_irr)
+ highest_irr = kvm_x86_ops->sync_pir_to_irr(apic->vcpu);
+ else
+ highest_irr = apic_find_highest_irr(apic);
if (highest_irr == -1 || (highest_irr & 0xF0) <= ppr)
return -1;
return highest_irr;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 08a4d3ab3455..dc4b8834caee 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4357,11 +4357,6 @@ static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
return;
}

-static void svm_sync_pir_to_irr(struct kvm_vcpu *vcpu)
-{
- return;
-}
-
static void svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
{
kvm_lapic_set_irr(vec, vcpu->arch.apic);
@@ -5371,7 +5366,6 @@ static inline void avic_post_state_restore(struct kvm_vcpu *vcpu)
.get_enable_apicv = svm_get_enable_apicv,
.refresh_apicv_exec_ctrl = svm_refresh_apicv_exec_ctrl,
.load_eoi_exitmap = svm_load_eoi_exitmap,
- .sync_pir_to_irr = svm_sync_pir_to_irr,
.hwapic_irr_update = svm_hwapic_irr_update,
.hwapic_isr_update = svm_hwapic_isr_update,
.apicv_post_state_restore = avic_post_state_restore,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index eab8ab023705..27e40b180242 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6660,8 +6660,10 @@ static __init int hardware_setup(void)
if (!cpu_has_vmx_ple())
ple_gap = 0;

- if (!cpu_has_vmx_apicv())
+ if (!cpu_has_vmx_apicv()) {
enable_apicv = 0;
+ kvm_x86_ops->sync_pir_to_irr = NULL;
+ }

if (cpu_has_vmx_tsc_scaling()) {
kvm_has_tsc_control = true;
@@ -8734,20 +8736,24 @@ static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
}
}

-static void vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu)
+static int vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ int max_irr;

- if (!pi_test_on(&vmx->pi_desc))
- return;
-
- pi_clear_on(&vmx->pi_desc);
- /*
- * IOMMU can write to PIR.ON, so the barrier matters even on UP.
- * But on x86 this is just a compiler barrier anyway.
- */
- smp_mb__after_atomic();
- kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
+ if (vcpu->arch.apicv_active && pi_test_on(&vmx->pi_desc)) {
+ pi_clear_on(&vmx->pi_desc);
+ /*
+ * IOMMU can write to PIR.ON, so the barrier matters even on UP.
+ * But on x86 this is just a compiler barrier anyway.
+ */
+ smp_mb__after_atomic();
+ max_irr = kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
+ } else {
+ max_irr = kvm_lapic_find_highest_irr(vcpu);
+ }
+ vmx_hwapic_irr_update(vcpu, max_irr);
+ return max_irr;
}

static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 641e9309ee08..c666414adc1d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2871,7 +2871,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
{
- if (vcpu->arch.apicv_active)
+ if (kvm_x86_ops->sync_pir_to_irr)
kvm_x86_ops->sync_pir_to_irr(vcpu);

return kvm_apic_get_state(vcpu, s);
@@ -6719,11 +6719,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
* Update architecture specific hints for APIC
* virtual interrupt delivery.
*/
- if (vcpu->arch.apicv_active) {
+ if (kvm_x86_ops->sync_pir_to_irr)
kvm_x86_ops->sync_pir_to_irr(vcpu);
- kvm_x86_ops->hwapic_irr_update(vcpu,
- kvm_lapic_find_highest_irr(vcpu));
- }
}

if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
--
1.8.3.1