From: Sean Christopherson <[email protected]> Explicitly mark the Xen shared info page as never being dirty tracked so that higher-level gpc APIs can be added to automatically take care of things like dirty tracking, without reintroducing the bug fixed by commit 55749769fe60 ("KVM: x86: Fix wall clock writes in Xen shared_info not to mark page dirty"). And because the code _looks_ buggy.
No functional change intended. Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: David Woodhouse <[email protected]> Assisted-by: LLM --- arch/x86/kvm/xen.c | 2 +- include/linux/kvm_host.h | 10 ++++++++-- include/linux/kvm_types.h | 1 + virt/kvm/pfncache.c | 4 +++- 4 files changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index a931458f0c71..f8162914d6c6 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -2469,7 +2469,7 @@ void kvm_xen_init_vm(struct kvm *kvm) { mutex_init(&kvm->arch.xen.xen_lock); xa_init(&kvm->arch.xen.evtchn_ports); - kvm_gpc_init(&kvm->arch.xen.shinfo_cache, kvm); + __kvm_gpc_init(&kvm->arch.xen.shinfo_cache, kvm, true); } void kvm_xen_destroy_vm(struct kvm *kvm) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 88c1ee37550c..1abd3811b953 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1465,7 +1465,13 @@ int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data, * immutable attributes. Note, the cache must be zero-allocated (or zeroed by * the caller before init). */ -void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm); +void __kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm, + bool never_dirty); + +static inline void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm) +{ + __kvm_gpc_init(gpc, kvm, false); +} /** * kvm_gpc_activate - prepare a cached kernel mapping and HPA for a given guest @@ -1987,7 +1993,7 @@ static inline void kvm_gpc_mark_dirty_in_slot(struct gfn_to_pfn_cache *gpc) { lockdep_assert_held(&gpc->lock); - if (!gpc->memslot) + if (!gpc->memslot || gpc->never_dirty) return; mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpa_to_gfn(gpc->gpa)); diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index a568d8e6f4e8..e850adc3f47e 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -94,6 +94,7 @@ struct gfn_to_pfn_cache { kvm_pfn_t pfn; bool active; bool valid; + bool never_dirty; }; #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 8504e26fa111..0e2c9cfa8056 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -431,7 +431,8 @@ int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len, bool wait) } } -void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm) +void __kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm, + bool never_dirty) { rwlock_init(&gpc->lock); mutex_init(&gpc->refresh_lock); @@ -441,6 +442,7 @@ void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm) gpc->gpa = INVALID_GPA; gpc->uhva = KVM_HVA_ERR_BAD; gpc->active = gpc->valid = false; + gpc->never_dirty = never_dirty; } static int __kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long uhva, -- 2.43.0
