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KVM: async_pf: Cleanup kvm_setup_async_pf()

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commit 7863e346e1 upstream.

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>
Message-Id: <20200610175532.779793-1-vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vitaly Kuznetsov 2020-06-10 19:55:31 +02:00 committed by Greg Kroah-Hartman
parent 90f43980ea
commit 7dc6e67f51
1 changed files with 6 additions and 13 deletions
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19
virt/kvm/async_pf.c
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@ -195,7 +195,9 @@ 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
@ -213,24 +215,15 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
work->mm = current->mm;
mmget(work->mm);
/* 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)