diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2023-01-11 18:06:48 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-01-11 13:32:21 -0500 |
| commit | 23e60258aeafb04e5dd813f03cb0c8ab7b01462a (patch) | |
| tree | 65a89b3df863d272ce0d6677862e6c558b6a5f0c | |
| parent | 71d0393576e9e1ef536c3bc3cf11f661c58dded9 (diff) | |
| download | linux-23e60258aeafb04e5dd813f03cb0c8ab7b01462a.tar.gz | |
KVM: x86/xen: Fix lockdep warning on "recursive" gpc locking
In commit 5ec3289b31 ("KVM: x86/xen: Compatibility fixes for shared runstate
area") we declared it safe to obtain two gfn_to_pfn_cache locks at the same
time:
/*
* The guest's runstate_info is split across two pages and we
* need to hold and validate both GPCs simultaneously. We can
* declare a lock ordering GPC1 > GPC2 because nothing else
* takes them more than one at a time.
*/
However, we forgot to tell lockdep. Do so, by setting a subclass on the
first lock before taking the second.
Fixes: 5ec3289b31 ("KVM: x86/xen: Compatibility fixes for shared runstate area")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20230111180651.14394-1-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/xen.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 2e29bdc2949ca..bfa9809721b5b 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -304,8 +304,10 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic) * The guest's runstate_info is split across two pages and we * need to hold and validate both GPCs simultaneously. We can * declare a lock ordering GPC1 > GPC2 because nothing else - * takes them more than one at a time. + * takes them more than one at a time. Set a subclass on the + * gpc1 lock to make lockdep shut up about it. */ + lock_set_subclass(&gpc1->lock.dep_map, 1, _THIS_IP_); read_lock(&gpc2->lock); if (!kvm_gpc_check(gpc2, user_len2)) { |