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Date: Wed, 11 Aug 2021 06:23:56 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: vkuznets@...hat.com, mtosatti@...hat.com
Subject: [PATCH 2/2] 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.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/include/asm/kvm_host.h | 1 -
arch/x86/kvm/x86.c | 66 +++++++++++++--------------------
2 files changed, 26 insertions(+), 41 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index bc6157677753..c54f9da91f99 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1839,7 +1839,6 @@ 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);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 284afaa1db86..8f96cdfcf364 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2757,35 +2757,36 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm)
#endif
}
-void kvm_make_mclock_inprogress_request(struct kvm *kvm)
+static void kvm_start_pvclock_update(struct kvm *kvm)
{
+ struct kvm_arch *ka = &kvm->arch;
kvm_make_all_cpus_request(kvm, KVM_REQ_MCLOCK_INPROGRESS);
+
+ /* no guest entries from this point */
+ spin_lock_irq(&ka->pvclock_gtod_sync_lock);
}
-static void kvm_gen_update_masterclock(struct kvm *kvm)
+static void kvm_end_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);
+ 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)
@@ -6077,12 +6078,10 @@ 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
@@ -6091,15 +6090,12 @@ 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: {
@@ -8105,9 +8101,7 @@ 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)
@@ -8121,19 +8115,11 @@ static void kvm_hyperv_tsc_notifier(void)
kvm_max_guest_tsc_khz = tsc_khz;
list_for_each_entry(kvm, &vm_list, vm_list) {
- struct kvm_arch *ka = &kvm->arch;
-
- kvm_make_mclock_inprogress_request(kvm);
- spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
+ kvm_start_pvclock_update(kvm);
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
@@ -9413,7 +9399,7 @@ 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)) {
--
2.27.0
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