This is a note to let you know that I've just added the patch titled
KVM: async_pf: Cleanup kvm_setup_async_pf()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-async_pf-cleanup-kvm_setup_async_pf.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7863e346e1089b40cac1c7d9098314c405e2e1e3 Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Date: Wed, 10 Jun 2020 19:55:31 +0200
Subject: KVM: async_pf: Cleanup kvm_setup_async_pf()
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
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@xxxxxxxxxx>
Message-Id: <20200610175532.779793-1-vkuznets@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)
Patches currently in stable-queue which might be from vkuznets@xxxxxxxxxx are
queue-5.4/kvm-async_pf-cleanup-kvm_setup_async_pf.patch
