lkml.org 
[lkml]   [2021]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] KVM: x86: reduce pvclock_gtod_sync_lock critical sections
Date
There is no need to include changes to vcpu->requests into
the pvclock_gtod_sync_lock critical section. The changes to
the shared data structures (in pvclock_update_vm_gtod_copy)
already occur under the lock.

Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fe806e894212..0a83eff40b43 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2562,10 +2562,12 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)

kvm_hv_invalidate_tsc_page(kvm);

- spin_lock(&ka->pvclock_gtod_sync_lock);
kvm_make_mclock_inprogress_request(kvm);
+
/* no guest entries from this point */
+ spin_lock(&ka->pvclock_gtod_sync_lock);
pvclock_update_vm_gtod_copy(kvm);
+ spin_unlock(&ka->pvclock_gtod_sync_lock);

kvm_for_each_vcpu(i, vcpu, kvm)
kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@@ -2573,8 +2575,6 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)
/* guest entries allowed */
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);
-
- spin_unlock(&ka->pvclock_gtod_sync_lock);
#endif
}

@@ -7740,16 +7740,14 @@ static void kvm_hyperv_tsc_notifier(void)
struct kvm_arch *ka = &kvm->arch;

spin_lock(&ka->pvclock_gtod_sync_lock);
-
pvclock_update_vm_gtod_copy(kvm);
+ spin_unlock(&ka->pvclock_gtod_sync_lock);

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);
-
- spin_unlock(&ka->pvclock_gtod_sync_lock);
}
mutex_unlock(&kvm_lock);
}
--
2.26.2

\
 
 \ /
  Last update: 2021-03-30 19:02    [W:0.098 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site