Re: [PATCH 3/3] KVM: x86: do not scan IRR twice on APICv vmentry
From: Yang Zhang
Date: Fri Oct 14 2016 - 03:32:48 EST
On 2016/9/28 5:20, Paolo Bonzini wrote:
Calling apic_find_highest_irr results in IRR being scanned twice,
once in vmx_sync_pir_from_irr and once in apic_search_irr. Change
vcpu_enter_guest to use sync_pir_from_irr (with a new argument to
trigger the RVI write), and let sync_pir_from_irr get the new RVI
directly from kvm_apic_update_irr.
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/lapic.c | 25 ++++++++++++++++---------
arch/x86/kvm/lapic.h | 4 ++--
arch/x86/kvm/svm.c | 2 +-
arch/x86/kvm/vmx.c | 25 ++++++++++++++-----------
arch/x86/kvm/x86.c | 7 +++----
6 files changed, 37 insertions(+), 28 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4b20f7304b9c..f73eea243567 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -941,7 +941,7 @@ 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);
+ void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu, bool sync_rvi);
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 be8b7ad56dd1..85b79b90e3d0 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -317,7 +317,7 @@ static int find_highest_vector(void *bitmap)
vec >= 0; vec -= APIC_VECTORS_PER_REG) {
reg = bitmap + REG_POS(vec);
if (*reg)
- return fls(*reg) - 1 + vec;
+ return __fls(*reg) + vec;
}
return -1;
@@ -337,25 +337,32 @@ static u8 count_vectors(void *bitmap)
return count;
}
-void __kvm_apic_update_irr(u32 *pir, void *regs)
+int __kvm_apic_update_irr(u32 *pir, void *regs)
{
- u32 i, pir_val;
+ u32 i, vec;
+ u32 pir_val, irr_val;
+ int max_irr = -1;
- for (i = 0; i <= 7; i++) {
+ for (i = vec = 0; i <= 7; i++, vec += 32) {
how about ignore the first 32 vectors since they cannot be used as
normal interrupt except nmi interrupt which is special handled.
pir_val = READ_ONCE(pir[i]);
+ irr_val = *((u32 *)(regs + APIC_IRR + i * 0x10));
if (pir_val) {
- pir_val = xchg(&pir[i], 0);
- *((u32 *)(regs + APIC_IRR + i * 0x10)) |= pir_val;
+ irr_val |= xchg(&pir[i], 0);
+ *((u32 *)(regs + APIC_IRR + i * 0x10)) = irr_val;
}
+ if (irr_val)
+ max_irr = __fls(irr_val) + vec;
}
+
+ return max_irr;
}
EXPORT_SYMBOL_GPL(__kvm_apic_update_irr);
-void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
+int kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
{
struct kvm_lapic *apic = vcpu->arch.apic;
- __kvm_apic_update_irr(pir, apic->regs);
+ return __kvm_apic_update_irr(pir, apic->regs);
}
EXPORT_SYMBOL_GPL(kvm_apic_update_irr);
@@ -376,7 +383,7 @@ static inline int apic_find_highest_irr(struct kvm_lapic *apic)
return -1;
if (apic->vcpu->arch.apicv_active)
- kvm_x86_ops->sync_pir_to_irr(apic->vcpu);
+ kvm_x86_ops->sync_pir_to_irr(apic->vcpu, false);
result = apic_search_irr(apic);
You have got the max_irr in sync_pir_to_irr. It seems the
apic_search_irr() is redundant here.
ASSERT(result == -1 || result >= 16);
I think the result must >= 32. But it seems this code exists when kvm
first merging into kernel.
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f60d01c29d51..fc72828c3782 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -70,8 +70,8 @@ int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len,
bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
int short_hand, unsigned int dest, int dest_mode);
-void __kvm_apic_update_irr(u32 *pir, void *regs);
-void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
+int __kvm_apic_update_irr(u32 *pir, void *regs);
+int kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
struct dest_map *dest_map);
int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 9b4221471e3d..60e53fa2b554 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4383,7 +4383,7 @@ 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)
+static void svm_sync_pir_to_irr(struct kvm_vcpu *vcpu, bool sync_rvi)
{
return;
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 207b9aa32915..1edefab54d01 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4852,17 +4852,6 @@ static void vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
kvm_vcpu_kick(vcpu);
}
-static void vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu)
-{
- struct vcpu_vmx *vmx = to_vmx(vcpu);
-
- if (!pi_test_on(&vmx->pi_desc) ||
- !pi_test_and_clear_on(&vmx->pi_desc))
- return;
-
- kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
-}
-
/*
* Set up the vmcs's constant host-state fields, i.e., host-state fields that
* will not change in the lifetime of the guest.
@@ -8609,6 +8598,20 @@ static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
}
}
+static void vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu, bool sync_rvi)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ int max_irr;
+
+ if (!pi_test_on(&vmx->pi_desc) ||
+ !pi_test_and_clear_on(&vmx->pi_desc))
+ return;
+
+ max_irr = kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
+ if (sync_rvi)
+ vmx_hwapic_irr_update(vcpu, max_irr);
+}
+
static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
{
if (!kvm_vcpu_apicv_active(vcpu))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 604cfbfc5bee..148e14fdc55d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2821,7 +2821,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
{
if (vcpu->arch.apicv_active)
- kvm_x86_ops->sync_pir_to_irr(vcpu);
+ kvm_x86_ops->sync_pir_to_irr(vcpu, false);
return kvm_apic_get_state(vcpu, s);
}
@@ -6448,7 +6448,7 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
kvm_scan_ioapic_routes(vcpu, vcpu->arch.ioapic_handled_vectors);
else {
if (vcpu->arch.apicv_active)
- kvm_x86_ops->sync_pir_to_irr(vcpu);
+ kvm_x86_ops->sync_pir_to_irr(vcpu, false);
kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
}
bitmap_or((ulong *)eoi_exit_bitmap, vcpu->arch.ioapic_handled_vectors,
@@ -6611,8 +6611,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
* virtual interrupt delivery.
*/
if (vcpu->arch.apicv_active)
- kvm_x86_ops->hwapic_irr_update(vcpu,
- kvm_lapic_find_highest_irr(vcpu));
+ kvm_x86_ops->sync_pir_to_irr(vcpu, true);
}
if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
--
Yang
Alibaba Cloud Computing