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KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask

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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@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-9-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2021-09-03 09:51:41 +02:00 committed by Paolo Bonzini
parent baff59ccdc
commit 620b2438ab
5 changed files with 12 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/kvm_host.h
View File

@ -581,7 +581,6 @@ 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 */

5
arch/x86/kvm/hyperv.c
View File

@ -1754,7 +1754,6 @@ 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];
@ -1836,8 +1835,6 @@ 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.
@ -1849,7 +1846,7 @@ 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:

9
arch/x86/kvm/x86.c
View File

@ -9242,14 +9242,7 @@ 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);
kvm_make_vcpus_request_mask(kvm, KVM_REQ_SCAN_IOAPIC, vcpu_bitmap);
}
void kvm_make_scan_ioapic_request(struct kvm *kvm)

2
include/linux/kvm_host.h
View File

@ -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);

29
virt/kvm/kvm_main.c
View File

@ -237,15 +237,8 @@ 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;
@ -254,7 +247,7 @@ 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;
@ -264,14 +257,6 @@ 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
@ -290,22 +275,26 @@ 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;