From 93984f19e7bce4c18084a6ef3dacafb155b806ed Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 29 Apr 2022 21:00:23 +0000 Subject: KVM: Fully serialize gfn=>pfn cache refresh via mutex Protect gfn=>pfn cache refresh with a mutex to fully serialize refreshes. The refresh logic doesn't protect against - concurrent unmaps, or refreshes with different GPAs (which may or may not happen in practice, for example if a cache is only used under vcpu->mutex; but it's allowed in the code) - a false negative on the memslot generation. If the first refresh sees a stale memslot generation, it will refresh the hva and generation before moving on to the hva=>pfn translation. If it then drops gpc->lock, a different user of the cache can come along, acquire gpc->lock, see that the memslot generation is fresh, and skip the hva=>pfn update due to the userspace address also matching (because it too was updated). The refresh path can already sleep during hva=>pfn resolution, so wrap the refresh with a mutex to ensure that any given refresh runs to completion before other callers can start their refresh. Cc: stable@vger.kernel.org Cc: Lai Jiangshan Signed-off-by: Sean Christopherson Message-Id: <20220429210025.3293691-7-seanjc@google.com> Signed-off-by: Paolo Bonzini --- include/linux/kvm_types.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index ac1ebb37a0ff..f328a01db4fe 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -19,6 +19,7 @@ struct kvm_memslots; enum kvm_mr_change; #include +#include #include #include @@ -69,6 +70,7 @@ struct gfn_to_pfn_cache { struct kvm_vcpu *vcpu; struct list_head list; rwlock_t lock; + struct mutex refresh_lock; void *khva; kvm_pfn_t pfn; enum pfn_cache_usage usage; -- cgit v1.2.3