linux-kernel - Re: [PATCH v8 17/19] grant-table: call set_phys_to

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Message-ID: <alpine.DEB.2.02.1310231815420.26077@kaball.uk.xensource.com>
Date:	Wed, 23 Oct 2013 18:15:56 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	<xen-devel@...ts.xensource.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <Ian.Campbell@...rix.com>
Subject: Re: [PATCH v8 17/19] grant-table: call set_phys_to_machine after
 mapping grant refs

On Wed, 23 Oct 2013, Konrad Rzeszutek Wilk wrote:
> On Thu, Oct 17, 2013 at 06:43:32PM +0100, Stefano Stabellini wrote:
> > When mapping/unmapping grant refs, call
> > set_phys_to_machine to update the P2M with the new mappings for
> > autotranslate guests.
> 
> Heh. That sounds so odd (p2m + xlat).
> Can you add a sentence saying that this is a mostly a nop on x86 please?
> 
> (Well, the call to set_phys_to_machine does end up with this check:
> 
>     if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
>                 BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
>                 return true;
>         }    
> But that should be a fairly small amount of code.
> 

Sure, I'll add a comment.

> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> > ---
> >  drivers/xen/grant-table.c |   17 +++++++++++++++--
> >  1 files changed, 15 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> > index 04cdeb8..a36cb03 100644
> > --- a/drivers/xen/grant-table.c
> > +++ b/drivers/xen/grant-table.c
> > @@ -49,6 +49,7 @@
> >  #include <xen/grant_table.h>
> >  #include <xen/interface/memory.h>
> >  #include <xen/hvc-console.h>
> > +#include <xen/swiotlb-xen.h>
> >  #include <asm/xen/hypercall.h>
> >  #include <asm/xen/interface.h>
> >  
> > @@ -889,8 +890,15 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
> >  			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
> >  						&map_ops[i].status, __func__);
> >  
> > -	if (xen_feature(XENFEAT_auto_translated_physmap))
> > +	if (xen_feature(XENFEAT_auto_translated_physmap)) {
> > +		for (i = 0; i < count; i++) {
> > +			if (map_ops[i].status)
> > +				continue;
> > +			set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,
> > +					map_ops[i].dev_bus_addr >> PAGE_SHIFT);
> > +		}
> >  		return ret;
> > +	}
> >  
> >  	if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
> >  		arch_enter_lazy_mmu_mode();
> > @@ -933,8 +941,13 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
> >  	if (ret)
> >  		return ret;
> >  
> > -	if (xen_feature(XENFEAT_auto_translated_physmap))
> > +	if (xen_feature(XENFEAT_auto_translated_physmap)) {
> > +		for (i = 0; i < count; i++) {
> > +			set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
> > +					INVALID_P2M_ENTRY);
> > +		}
> >  		return ret;
> > +	}
> >  
> >  	if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
> >  		arch_enter_lazy_mmu_mode();
> > -- 
> > 1.7.2.5
> > 
> 
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