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Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: On Wed, Jul 19, 2023, Paolo Bonzini wrote: > On 7/19/23 01:44, Sean Christopherson wrote: > > + BUILD_BUG_ON(sizeof(gfn_range.arg) != sizeof(gfn_range.arg.raw)); > > + BUILD_BUG_ON(sizeof(range->arg) != sizeof(range->arg.raw)); > > I think these should be static assertions near the definition of the > structs. However another possibility is to remove 'raw' and just assign the > whole union. Duh, and use a named union. I think when I first proposed this I forgot that a single value would be passed between kvm_hva_range *and* kvm_gfn_range, and so created an anonymous union without thinking about the impliciations. A named union is _much_ cleaner. I'll post a complete version of the below snippet as a standalone non-RFC patch. diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9d3ac7720da9..9125d0ab642d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -256,11 +256,15 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); #endif #ifdef KVM_ARCH_WANT_MMU_NOTIFIER +union kvm_mmu_notifier_arg { + pte_t pte; +}; + struct kvm_gfn_range { struct kvm_memory_slot *slot; gfn_t start; gfn_t end; - pte_t pte; + union kvm_mmu_notifier_arg arg; bool may_block; }; bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dfbaafbe3a00..f84ef9399aee 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -526,7 +526,7 @@ typedef void (*on_unlock_fn_t)(struct kvm *kvm); struct kvm_hva_range { unsigned long start; unsigned long end; - pte_t pte; + union kvm_mmu_notifier_arg arg; hva_handler_t handler; on_lock_fn_t on_lock; on_unlock_fn_t on_unlock; @@ -547,6 +547,8 @@ static void kvm_null_fn(void) } #define IS_KVM_NULL_FN(fn) ((fn) == (void *)kvm_null_fn) +static const union kvm_mmu_notifier_arg KVM_NO_ARG; + /* Iterate over each memslot intersecting [start, last] (inclusive) range */ #define kvm_for_each_memslot_in_hva_range(node, slots, start, last) \ for (node = interval_tree_iter_first(&slots->hva_tree, start, last); \ @@ -591,7 +593,7 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm, * bother making these conditional (to avoid writes on * the second or later invocation of the handler). */ - gfn_range.pte = range->pte; + gfn_range.arg = range->arg; gfn_range.may_block = range->may_block; /*