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Code Issues Releases Wiki Activity

kvm: x86: abstract locking around pvclock_update_vm_gtod_copy

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Updates to the kvmclock parameters needs to do a complicated dance of
KVM_REQ_MCLOCK_INPROGRESS and KVM_REQ_CLOCK_UPDATE in addition to taking
pvclock_gtod_sync_lock.  Place that in two functions that can be called
on all of master clock update, KVM_SET_CLOCK, and Hyper-V reenlightenment.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-09-16 18:15:32 +00:00
parent 3e44dce4d0
commit 6b6fcd2804
2 changed files with 29 additions and 34 deletions
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1
arch/x86/include/asm/kvm_host.h
View file

@ -1862,7 +1862,6 @@ u64 kvm_calc_nested_tsc_multiplier(u64 l1_multiplier, u64 l2_multiplier);
unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu);
bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
void kvm_make_mclock_inprogress_request(struct kvm *kvm);
void kvm_make_scan_ioapic_request(struct kvm *kvm);
void kvm_make_scan_ioapic_request_mask(struct kvm *kvm,
unsigned long *vcpu_bitmap);

62
arch/x86/kvm/x86.c
View file

@ -2743,35 +2743,42 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm)
#endif
}
void kvm_make_mclock_inprogress_request(struct kvm *kvm)
static void kvm_make_mclock_inprogress_request(struct kvm *kvm)
{
kvm_make_all_cpus_request(kvm, KVM_REQ_MCLOCK_INPROGRESS);
}
static void kvm_gen_update_masterclock(struct kvm *kvm)
static void kvm_start_pvclock_update(struct kvm *kvm)
{
#ifdef CONFIG_X86_64
int i;
struct kvm_vcpu *vcpu;
struct kvm_arch *ka = &kvm->arch;
unsigned long flags;
kvm_hv_invalidate_tsc_page(kvm);
kvm_make_mclock_inprogress_request(kvm);
/* no guest entries from this point */
spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
pvclock_update_vm_gtod_copy(kvm);
spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
spin_lock_irq(&ka->pvclock_gtod_sync_lock);
}
static void kvm_end_pvclock_update(struct kvm *kvm)
{
struct kvm_arch *ka = &kvm->arch;
struct kvm_vcpu *vcpu;
int i;
spin_unlock_irq(&ka->pvclock_gtod_sync_lock);
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
/* guest entries allowed */
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);
#endif
}
static void kvm_update_masterclock(struct kvm *kvm)
{
kvm_hv_invalidate_tsc_page(kvm);
kvm_start_pvclock_update(kvm);
pvclock_update_vm_gtod_copy(kvm);
kvm_end_pvclock_update(kvm);
}
u64 get_kvmclock_ns(struct kvm *kvm)
@ -6067,12 +6074,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
r = 0;
/*
* TODO: userspace has to take care of races with VCPU_RUN, so
* kvm_gen_update_masterclock() can be cut down to locked
* pvclock_update_vm_gtod_copy().
*/
kvm_gen_update_masterclock(kvm);
kvm_hv_invalidate_tsc_page(kvm);
kvm_start_pvclock_update(kvm);
pvclock_update_vm_gtod_copy(kvm);
/*
* This pairs with kvm_guest_time_update(): when masterclock is
@ -6081,15 +6086,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
* is slightly ahead) here we risk going negative on unsigned
* 'system_time' when 'user_ns.clock' is very small.
*/
spin_lock_irq(&ka->pvclock_gtod_sync_lock);
if (kvm->arch.use_master_clock)
now_ns = ka->master_kernel_ns;
else
now_ns = get_kvmclock_base_ns();
ka->kvmclock_offset = user_ns.clock - now_ns;
spin_unlock_irq(&ka->pvclock_gtod_sync_lock);
kvm_make_all_cpus_request(kvm, KVM_REQ_CLOCK_UPDATE);
kvm_end_pvclock_update(kvm);
break;
}
case KVM_GET_CLOCK: {
@ -8102,14 +8104,13 @@ static void tsc_khz_changed(void *data)
static void kvm_hyperv_tsc_notifier(void)
{
struct kvm *kvm;
struct kvm_vcpu *vcpu;
int cpu;
unsigned long flags;
mutex_lock(&kvm_lock);
list_for_each_entry(kvm, &vm_list, vm_list)
kvm_make_mclock_inprogress_request(kvm);
/* no guest entries from this point */
hyperv_stop_tsc_emulation();
/* TSC frequency always matches when on Hyper-V */
@ -8120,16 +8121,11 @@ static void kvm_hyperv_tsc_notifier(void)
list_for_each_entry(kvm, &vm_list, vm_list) {
struct kvm_arch *ka = &kvm->arch;
spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
spin_lock_irq(&ka->pvclock_gtod_sync_lock);
pvclock_update_vm_gtod_copy(kvm);
spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
kvm_for_each_vcpu(cpu, vcpu, kvm)
kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
kvm_for_each_vcpu(cpu, vcpu, kvm)
kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);
kvm_end_pvclock_update(kvm);
}
mutex_unlock(&kvm_lock);
}
#endif
@ -9406,7 +9402,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu))
__kvm_migrate_timers(vcpu);
if (kvm_check_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu))
kvm_gen_update_masterclock(vcpu->kvm);
kvm_update_masterclock(vcpu->kvm);
if (kvm_check_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu))
kvm_gen_kvmclock_update(vcpu);
if (kvm_check_request(KVM_REQ_CLOCK_UPDATE, vcpu)) {