Re: [Xen-devel] [PATCH v2 6/8] x86/hyperv: provide percpu hypercall input page

From: Wei Liu <wl@xen.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Wei Liu" <liuwe@microsoft.com>, "Wei Liu" <wl@xen.org>,
	"Paul Durrant" <paul@xen.org>,
	"Michael Kelley" <mikelley@microsoft.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Xen Development List" <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v2 6/8] x86/hyperv: provide percpu hypercall input page
Date: Fri, 3 Jan 2020 16:55:13 +0000	[thread overview]
Message-ID: <20200103165513.wlgihc4kfqducwtm@debian> (raw)
In-Reply-To: <ec797a21-8b06-6eb1-84a8-7e059c430e7a@citrix.com>

On Fri, Jan 03, 2020 at 04:30:49PM +0000, Andrew Cooper wrote:
> On 03/01/2020 16:08, Wei Liu wrote:
> > @@ -83,14 +84,39 @@ static void __init setup_hypercall_page(void)
> >      wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> >  }
> >  
> > +static void setup_hypercall_pcpu_arg(void)
> > +{
> > +    struct page_info *pg;
> > +    void *mapping;
> > +    unsigned int cpu = smp_processor_id();
> > +
> > +    pg = alloc_domheap_page(NULL, 0);
> > +    if ( !pg )
> > +        panic("Failed to setup hypercall input page for %u\n", cpu);
> > +
> > +    mapping = __map_domain_page_global(pg);
> > +    if ( !mapping )
> > +        panic("Failed to map hypercall input page for %u\n", cpu);
> 
> Sorry I didn't spot this before, but an always-mapped domheap page is
> just alloc_xenheap_page() (give or take NUMA positioning above the 5T
> boundary, which isn't used here).

I had the (wrong) impression that using domheap was preferred.

I'm fine with switching to xenheap, of course.

Wei.

> 
> ~Andrew

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