Re: [Xen-devel] [PATCH 17/17] xen: Switch parameter in get_page_from_gfn to use typesafe gfn

From: Julien Grall <julien@xen.org>
To: paul@xen.org, xen-devel@lists.xenproject.org
Cc: "'Kevin Tian'" <kevin.tian@intel.com>,
	"'Stefano Stabellini'" <sstabellini@kernel.org>,
	"'Jun Nakajima'" <jun.nakajima@intel.com>,
	"'Wei Liu'" <wl@xen.org>,
	"'Andrew Cooper'" <andrew.cooper3@citrix.com>,
	"'Ian Jackson'" <ian.jackson@eu.citrix.com>,
	"'George Dunlap'" <george.dunlap@citrix.com>,
	"'Tim Deegan'" <tim@xen.org>,
	"'Julien Grall'" <julien.grall@arm.com>,
	"'Jan Beulich'" <jbeulich@suse.com>,
	"'Volodymyr Babchuk'" <Volodymyr_Babchuk@epam.com>,
	"'Roger Pau Monné'" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 17/17] xen: Switch parameter in get_page_from_gfn to use typesafe gfn
Date: Mon, 23 Mar 2020 10:26:07 +0000	[thread overview]
Message-ID: <aa254dec-e856-2693-8d12-3dc1b2bc0ca7@xen.org> (raw)
In-Reply-To: <002101d600ee$5120aa40$f361fec0$@xen.org>

Hi Paul,

On 23/03/2020 08:37, Paul Durrant wrote:
>> -----Original Message-----
>> From: julien@xen.org <julien@xen.org>
>> Sent: 22 March 2020 16:14
>> To: xen-devel@lists.xenproject.org
>> Cc: julien@xen.org; Julien Grall <julien.grall@arm.com>; Stefano Stabellini <sstabellini@kernel.org>;
>> Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>; Andrew Cooper <andrew.cooper3@citrix.com>; George
>> Dunlap <george.dunlap@citrix.com>; Ian Jackson <ian.jackson@eu.citrix.com>; Jan Beulich
>> <jbeulich@suse.com>; Wei Liu <wl@xen.org>; Roger Pau Monné <roger.pau@citrix.com>; Paul Durrant
>> <paul@xen.org>; Jun Nakajima <jun.nakajima@intel.com>; Kevin Tian <kevin.tian@intel.com>; Tim Deegan
>> <tim@xen.org>
>> Subject: [PATCH 17/17] xen: Switch parameter in get_page_from_gfn to use typesafe gfn
>>
>> From: Julien Grall <julien.grall@arm.com>
>>
>> No functional change intended.
>>
>> Only reasonable clean-ups are done in this patch. The rest will use _gfn
>> for the time being.
>>
>> Signed-off-by: Julien Grall <julien.grall@arm.com>
> 
> Definitely an improvement so...
> 
> Reviewed-by: Paul Durrant <paul@xen.org>
> 
> But a couple of things I noticed...
> 
> [snip]
>> diff --git a/xen/arch/x86/hvm/domain.c b/xen/arch/x86/hvm/domain.c
>> index 5d5a746a25..3c29ff86be 100644
>> --- a/xen/arch/x86/hvm/domain.c
>> +++ b/xen/arch/x86/hvm/domain.c
>> @@ -296,8 +296,10 @@ int arch_set_info_hvm_guest(struct vcpu *v, const vcpu_hvm_context_t *ctx)
>>       if ( hvm_paging_enabled(v) && !paging_mode_hap(v->domain) )
>>       {
>>           /* Shadow-mode CR3 change. Check PDBR and update refcounts. */
>> -        struct page_info *page = get_page_from_gfn(v->domain,
>> -                                 v->arch.hvm.guest_cr[3] >> PAGE_SHIFT,
>> +        struct page_info *page;
>> +
>> +        page = get_page_from_gfn(v->domain,
>> +                                 gaddr_to_gfn(v->arch.hvm.guest_cr[3]),
> 
> Should this be cr3_to_gfn?

Definitely yes. I thought I spotted all the use when introducing the new 
helper but it looks like not. I will update the patch in the new version 
to use cr3_to_gfn() everywhere you suggested.

Thanks.

Cheers,

-- 
Julien Grall

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