5.4-stable review patch. If anyone has any objections, please let me know.
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From: Vitaly Kuznetsov vkuznets@redhat.com
commit 7863e346e1089b40cac1c7d9098314c405e2e1e3 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 --- virt/kvm/async_pf.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-)
--- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -195,7 +195,9 @@ int kvm_setup_async_pf(struct kvm_vcpu * 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 * 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)