Commit 6b6fcd28 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

kvm: x86: abstract locking around pvclock_update_vm_gtod_copy 



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: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 3e44dce4

arch/x86/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/x86.c

+29 −33
Original line number Diff line number Diff line
@@ -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)) {