Re: [PATCH 06/22] kvm: mmu: Make address space ID a property of memslots

[Sean Christopherson]

On Fri, Sep 25, 2020 at 02:22:46PM -0700, Ben Gardon wrote:
> Save address space ID as a field in each memslot so that functions that
> do not use rmaps (which implicitly encode the id) can handle multiple
> address spaces correctly.
> 
> Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
> machine. This series introduced no new failures.
> 
> This series can be viewed in Gerrit at:
> 	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538
> 
> Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
> ---
>  include/linux/kvm_host.h | 1 +
>  virt/kvm/kvm_main.c      | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 05e3c2fb3ef78..a460bc712a81c 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -345,6 +345,7 @@ struct kvm_memory_slot {
>  	struct kvm_arch_memory_slot arch;
>  	unsigned long userspace_addr;
>  	u32 flags;
> +	int as_id;

Ha!  Peter Xu's dirtly ring also added this.  This should be a u16, it'll
save 8 bytes per memslot (oooooooh).  Any chance you want to include Peter's
patch[*]?  It has some nitpicking from Peter and I regarding what to do
with as_id on deletion.  That would also avoid silent merge conflicts on
Peter's end.

[*] https://lkml.kernel.org/r/20200708193408.242909-2-peterx@xxxxxxxxxx

>  	short id;
>  };
>  
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index cf88233b819a0..f9c80351c9efd 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1318,6 +1318,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  	new.npages = mem->memory_size >> PAGE_SHIFT;
>  	new.flags = mem->flags;
>  	new.userspace_addr = mem->userspace_addr;
> +	new.as_id = as_id;
>  
>  	if (new.npages > KVM_MEM_MAX_NR_PAGES)
>  		return -EINVAL;
> -- 
> 2.28.0.709.gb0816b6eb0-goog
>