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Message-Id: <20210903075141.403071-9-vkuznets@redhat.com>
Date: Fri, 3 Sep 2021 09:51:41 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <seanjc@...gle.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
"Dr. David Alan Gilbert" <dgilbert@...hat.com>,
Nitesh Narayan Lal <nitesh@...hat.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
Maxim Levitsky <mlevitsk@...hat.com>,
Eduardo Habkost <ehabkost@...hat.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH v5 8/8] KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask
kvm_make_vcpus_request_mask() already disables preemption so just like
kvm_make_all_cpus_request_except() it can be switched to using
pre-allocated per-cpu cpumasks. This allows for improvements for both
users of the function: in Hyper-V emulation code 'tlb_flush' can now be
dropped from 'struct kvm_vcpu_hv' and kvm_make_scan_ioapic_request_mask()
gets rid of dynamic allocation.
cpumask_available() checks in kvm_make_vcpu_request() and
kvm_kick_many_cpus() can now be dropped as they checks for an impossible
condition: kvm_init() makes sure per-cpu masks are allocated.
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
arch/x86/include/asm/kvm_host.h | 1 -
arch/x86/kvm/hyperv.c | 5 +----
arch/x86/kvm/x86.c | 8 +-------
include/linux/kvm_host.h | 2 +-
virt/kvm/kvm_main.c | 29 +++++++++--------------------
5 files changed, 12 insertions(+), 33 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 09b256db394a..846552fa2012 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -569,7 +569,6 @@ struct kvm_vcpu_hv {
struct kvm_hyperv_exit exit;
struct kvm_vcpu_hv_stimer stimer[HV_SYNIC_STIMER_COUNT];
DECLARE_BITMAP(stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
- cpumask_t tlb_flush;
bool enforce_cpuid;
struct {
u32 features_eax; /* HYPERV_CPUID_FEATURES.EAX */
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 5704bfe53ee0..f76e7228f687 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1755,7 +1755,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
int i;
gpa_t gpa;
struct kvm *kvm = vcpu->kvm;
- struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
struct hv_tlb_flush_ex flush_ex;
struct hv_tlb_flush flush;
u64 vp_bitmap[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
@@ -1837,8 +1836,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
}
}
- cpumask_clear(&hv_vcpu->tlb_flush);
-
/*
* vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't
* analyze it here, flush TLB regardless of the specified address space.
@@ -1850,7 +1847,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
vp_bitmap, vcpu_bitmap);
kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST,
- vcpu_mask, &hv_vcpu->tlb_flush);
+ vcpu_mask);
}
ret_success:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a4752dcc2a75..91c1e6c98b0f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9224,14 +9224,8 @@ static void process_smi(struct kvm_vcpu *vcpu)
void kvm_make_scan_ioapic_request_mask(struct kvm *kvm,
unsigned long *vcpu_bitmap)
{
- cpumask_var_t cpus;
-
- zalloc_cpumask_var(&cpus, GFP_ATOMIC);
-
kvm_make_vcpus_request_mask(kvm, KVM_REQ_SCAN_IOAPIC,
- vcpu_bitmap, cpus);
-
- free_cpumask_var(cpus);
+ vcpu_bitmap);
}
void kvm_make_scan_ioapic_request(struct kvm *kvm)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2f149ed140f7..1ee85de0bf74 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -160,7 +160,7 @@ static inline bool is_error_page(struct page *page)
#define KVM_ARCH_REQ(nr) KVM_ARCH_REQ_FLAGS(nr, 0)
bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
- unsigned long *vcpu_bitmap, cpumask_var_t tmp);
+ unsigned long *vcpu_bitmap);
bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req);
bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
struct kvm_vcpu *except);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ddd091f05c18..12dbf3f062da 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -247,15 +247,8 @@ static void ack_flush(void *_completed)
{
}
-static inline bool kvm_kick_many_cpus(cpumask_var_t tmp, bool wait)
+static inline bool kvm_kick_many_cpus(struct cpumask *cpus, bool wait)
{
- const struct cpumask *cpus;
-
- if (likely(cpumask_available(tmp)))
- cpus = tmp;
- else
- cpus = cpu_online_mask;
-
if (cpumask_empty(cpus))
return false;
@@ -264,7 +257,7 @@ static inline bool kvm_kick_many_cpus(cpumask_var_t tmp, bool wait)
}
static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
- unsigned int req, cpumask_var_t tmp,
+ unsigned int req, struct cpumask *tmp,
int current_cpu)
{
int cpu;
@@ -274,14 +267,6 @@ static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
return;
- /*
- * tmp can be "unavailable" if cpumasks are allocated off stack as
- * allocation of the mask is deliberately not fatal and is handled by
- * falling back to kicking all online CPUs.
- */
- if (!cpumask_available(tmp))
- return;
-
/*
* Note, the vCPU could get migrated to a different pCPU at any point
* after kvm_request_needs_ipi(), which could result in sending an IPI
@@ -300,22 +285,26 @@ static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
}
bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
- unsigned long *vcpu_bitmap, cpumask_var_t tmp)
+ unsigned long *vcpu_bitmap)
{
struct kvm_vcpu *vcpu;
+ struct cpumask *cpus;
int i, me;
bool called;
me = get_cpu();
+ cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
+ cpumask_clear(cpus);
+
for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) {
vcpu = kvm_get_vcpu(kvm, i);
if (!vcpu)
continue;
- kvm_make_vcpu_request(kvm, vcpu, req, tmp, me);
+ kvm_make_vcpu_request(kvm, vcpu, req, cpus, me);
}
- called = kvm_kick_many_cpus(tmp, !!(req & KVM_REQUEST_WAIT));
+ called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
put_cpu();
return called;
--
2.31.1
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