lkml.org 
[lkml]   [2020]   [Jun]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] KVM: async_pf: Cleanup kvm_setup_async_pf()
Date
schedule_work() returns 'false' only when the work is already on the queue
and this can't happen as kvm_setup_async_pf() always allocates a new one.
Also, to avoid potential race, it makes sense to to schedule_work() at the
very end after we've added it to the queue.

While on it, do some minor cleanup. gfn_to_pfn_async() mentioned in a
comment does not currently exist and, moreover, we can check
kvm_is_error_hva() at the very beginning, before we try to allocate work so
'retry_sync' label can go away completely.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
virt/kvm/async_pf.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index f1e07fae84e9..ba080088da76 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -164,7 +164,9 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
return 0;

- /* setup delayed work */
+ /* Arch specific code should not do async PF in this case */
+ if (unlikely(kvm_is_error_hva(hva)))
+ return 0;

/*
* do alloc nowait since if we are going to sleep anyway we
@@ -183,24 +185,15 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
mmget(work->mm);
kvm_get_kvm(work->vcpu->kvm);

- /* this can't really happen otherwise gfn_to_pfn_async
- would succeed */
- if (unlikely(kvm_is_error_hva(work->addr)))
- goto retry_sync;
-
INIT_WORK(&work->work, async_pf_execute);
- if (!schedule_work(&work->work))
- goto retry_sync;

list_add_tail(&work->queue, &vcpu->async_pf.queue);
vcpu->async_pf.queued++;
kvm_arch_async_page_not_present(vcpu, work);
+
+ schedule_work(&work->work);
+
return 1;
-retry_sync:
- kvm_put_kvm(work->vcpu->kvm);
- mmput(work->mm);
- kmem_cache_free(async_pf_cache, work);
- return 0;
}

int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
--
2.25.4
\
 
 \ /
  Last update: 2020-06-10 19:56    [W:0.081 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site