Re: [Xen-devel] [PATCH v2 01/20] x86: make hvm_{get/set}_param accessible

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Thu, Dec 19, 2019 at 12:41 PM Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
>
> On 19/12/2019 19:38, Tamas K Lengyel wrote:
> >>> --- a/xen/include/asm-x86/hvm/hvm.h
> >>> +++ b/xen/include/asm-x86/hvm/hvm.h
> >>> @@ -335,6 +335,10 @@ unsigned long hvm_cr4_guest_valid_bits(const struct 
> >>> domain *d, bool restore);
> >>>  bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
> >>>                          void *ctxt);
> >>>
> >>> +/* Caller must hold domain locks */
> >> How about asserting so?
> > AFAICT there is no "domain_locked_by_me" function, only
> > paging/p2m/gfn_locked_by_me. So any suggestion on how to achieve that?
>
> spin_is_locked() gets you most of the way, and would be a start.
>
> But yes - now you say this, I remember that we don't currently have
> suitable infrastructure.

Is the domain lock even a spin lock (the on you use by
rcu_lock_live_remote_domain_by_id)? Looks to me it just goes down to
"rcu_read_lock" which only does a preempt_disable() call o.O

Tamas

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