linux-kernel - Re: [PATCH RESEND v2 04/17] KVM: Cache as_id in kvm_memory

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Date:   Wed, 8 Jan 2020 18:47:17 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Peter Xu <peterx@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        Christophe de Dinechin <dinechin@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH RESEND v2 04/17] KVM: Cache as_id in kvm_memory_slot

On 21/12/19 02:49, Peter Xu wrote:
> Let's cache the address space ID just like the slot ID.

Please add a not that it will be useful in order to fill in the dirty
page ring buffer.

Paolo

> Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
> Suggested-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  include/linux/kvm_host.h | 1 +
>  virt/kvm/kvm_main.c      | 2 ++
>  2 files changed, 3 insertions(+)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 4e34cf97ca90..24854c9e3717 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -348,6 +348,7 @@ struct kvm_memory_slot {
>  	unsigned long userspace_addr;
>  	u32 flags;
>  	short id;
> +	u8 as_id;
>  };
>  
>  static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index b1047173d78e..cea4b8dd4ac9 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1027,6 +1027,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  
>  	new = old = *slot;
>  
> +	BUILD_BUG_ON(U8_MAX < KVM_ADDRESS_SPACE_NUM);
> +	new.as_id = as_id;
>  	new.id = id;
>  	new.base_gfn = base_gfn;
>  	new.npages = npages;
>