[v6,02/14] KVM: Cache as_id in kvm_memory_slot
diff mbox series

Message ID 20200309214424.330363-3-peterx@redhat.com
State New
Headers show
Series
  • KVM: Dirty ring interface
Related show

Commit Message

Peter Xu March 9, 2020, 9:44 p.m. UTC
Cache the address space ID just like the slot ID.  It will be used in
order to fill in the dirty ring entries.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/linux/kvm_host.h | 1 +
 virt/kvm/kvm_main.c      | 2 ++
 2 files changed, 3 insertions(+)

Comments

Sean Christopherson March 10, 2020, 2:48 p.m. UTC | #1
On Mon, Mar 09, 2020 at 05:44:12PM -0400, Peter Xu wrote:
> Cache the address space ID just like the slot ID.  It will be used in
> order to fill in the dirty ring entries.
> 
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Peter Xu <peterx@redhat.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 bcb9b2ac0791..afa0e9034881 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -346,6 +346,7 @@ struct kvm_memory_slot {
>  	unsigned long userspace_addr;
>  	u32 flags;
>  	short id;
> +	u8 as_id;

My vote is to store this as a u16 and remove the BUILD_BUG_ON.  Using a u8
doesn't save any memory since the compiler will pad out the struct.

>  };
>  
>  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 70f03ce0e5c1..e6484dabfc59 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1036,6 +1036,8 @@ 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;
> -- 
> 2.24.1
>
Peter Xu March 11, 2020, 3:48 p.m. UTC | #2
On Tue, Mar 10, 2020 at 07:48:59AM -0700, Sean Christopherson wrote:
> On Mon, Mar 09, 2020 at 05:44:12PM -0400, Peter Xu wrote:
> > Cache the address space ID just like the slot ID.  It will be used in
> > order to fill in the dirty ring entries.
> > 
> > Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> > Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Signed-off-by: Peter Xu <peterx@redhat.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 bcb9b2ac0791..afa0e9034881 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -346,6 +346,7 @@ struct kvm_memory_slot {
> >  	unsigned long userspace_addr;
> >  	u32 flags;
> >  	short id;
> > +	u8 as_id;
> 
> My vote is to store this as a u16 and remove the BUILD_BUG_ON.  Using a u8
> doesn't save any memory since the compiler will pad out the struct.

Sure. Indeed that BUILD_BUG_ON does not help much in this case.  Thanks,

> 
> >  };
> >  
> >  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 70f03ce0e5c1..e6484dabfc59 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1036,6 +1036,8 @@ 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;
> > -- 
> > 2.24.1
> > 
>

Patch
diff mbox series

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bcb9b2ac0791..afa0e9034881 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -346,6 +346,7 @@  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 70f03ce0e5c1..e6484dabfc59 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1036,6 +1036,8 @@  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;