Re: swapping with MMU Notifiers V2

[Carsten Otte <cotte-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>]

Andrea Arcangeli wrote:
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index ea4764b..9349160 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -15,6 +15,7 @@
>  #include <linux/sched.h>
>  #include <linux/mm.h>
>  #include <linux/preempt.h>
> +#include <linux/mmu_notifier.h>
>  #include <asm/signal.h>
> 
>  #include <linux/kvm.h>
> @@ -118,6 +119,7 @@ struct kvm {
>  	struct kvm_io_bus pio_bus;
>  	struct kvm_vm_stat stat;
>  	struct kvm_arch arch;
> +	struct mmu_notifier mmu_notifier;
>  };
> 
>  /* The guest did something we don't support. */
This should not be in struct kvm, it should go to x86's kvm_arch. This 
is x86 specific, we don't need a notifier since the core-vm will just 
page out our guest memory like regular userspace mem.

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 8fc12dc..bb4747c 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -165,6 +165,7 @@ static struct kvm *kvm_create_vm(void)
> 
>  	kvm->mm = current->mm;
>  	atomic_inc(&kvm->mm->mm_count);
> +	mmu_notifier_register(&kvm->mmu_notifier, kvm->mm);
>  	spin_lock_init(&kvm->mmu_lock);
>  	kvm_io_bus_init(&kvm->pio_bus);
>  	mutex_init(&kvm->lock);
to kvm_arch_create_vm please

> @@ -1265,7 +1266,11 @@ static int kvm_resume(struct sys_device *dev)
>  }
> 
>  static struct sysdev_class kvm_sysdev_class = {
> +#ifdef set_kset_name
>  	set_kset_name("kvm"),
> +#else
> +	.name = "kvm",
> +#endif
>  	.suspend = kvm_suspend,
>  	.resume = kvm_resume,
>  };

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4295623..a67e38f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -298,7 +299,15 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  		memset(new.rmap, 0, npages * sizeof(*new.rmap));
> 
>  		new.user_alloc = user_alloc;
> -		new.userspace_addr = mem->userspace_addr;
> +		/*
> +		 * hva_to_rmmap() serialzies with the mmu_lock and to be
> +		 * safe it has to ignore memslots with !user_alloc &&
> +		 * !userspace_addr.
> +		 */
> +		if (user_alloc)
> +			new.userspace_addr = mem->userspace_addr;
> +		else
> +			new.userspace_addr = 0;
>  	}
> 
>  	/* Allocate page dirty bitmap if needed */
> @@ -311,14 +320,18 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  		memset(new.dirty_bitmap, 0, dirty_bytes);
>  	}
> 
> +	spin_lock(&kvm->mmu_lock);
>  	if (mem->slot >= kvm->nmemslots)
>  		kvm->nmemslots = mem->slot + 1;
> 
>  	*memslot = new;
> +	spin_unlock(&kvm->mmu_lock);
> 
>  	r = kvm_arch_set_memory_region(kvm, mem, old, user_alloc);
>  	if (r) {
> +		spin_lock(&kvm->mmu_lock);
>  		*memslot = old;
> +		spin_unlock(&kvm->mmu_lock);
>  		goto out_free;
>  	}
> 
> 
> 
This needs to go to arch too.

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