From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
"Wei Liu" <wl@xen.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Ian Jackson" <ian.jackson@eu.citrix.com>,
"George Dunlap" <george.dunlap@citrix.com>,
"Julien Grall" <julien.grall@arm.com>,
"Tamas K Lengyel" <tamas@tklengyel.com>,
xen-devel@lists.xenproject.org,
"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 16/17] xen/mm: Convert {s, g}et_gpfn_from_mfn() to use typesafe MFN
Date: Sat, 28 Mar 2020 11:14:16 +0000 [thread overview]
Message-ID: <c640eb5b-224f-e99a-daa2-6def00780e54@xen.org> (raw)
In-Reply-To: <a3d120d0-d67f-bed2-4920-0d3a1c3090ea@suse.com>
Hi,
On 27/03/2020 13:15, Jan Beulich wrote:
> On 22.03.2020 17:14, julien@xen.org wrote:
>> @@ -983,19 +984,20 @@ long p2m_pt_audit_p2m(struct p2m_domain *p2m)
>> /* check for 1GB super page */
>> if ( l3e_get_flags(l3e[i3]) & _PAGE_PSE )
>> {
>> - mfn = l3e_get_pfn(l3e[i3]);
>> - ASSERT(mfn_valid(_mfn(mfn)));
>> + mfn = l3e_get_mfn(l3e[i3]);
>> + ASSERT(mfn_valid(mfn));
>> /* we have to cover 512x512 4K pages */
>> for ( i2 = 0;
>> i2 < (L2_PAGETABLE_ENTRIES * L1_PAGETABLE_ENTRIES);
>> i2++)
>> {
>> - m2pfn = get_gpfn_from_mfn(mfn+i2);
>> + m2pfn = get_pfn_from_mfn(mfn_add(mfn, i2));
>> if ( m2pfn != (gfn + i2) )
>> {
>> pmbad++;
>> - P2M_PRINTK("mismatch: gfn %#lx -> mfn %#lx -> gfn %#lx\n",
>> - gfn + i2, mfn + i2, m2pfn);
>> + P2M_PRINTK("mismatch: gfn %#lx -> mfn %"PRI_mfn" gfn %#lx\n",
>> + gfn + i2, mfn_x(mfn_add(mfn, i2)),
>
> As in the earlier patch, "mfn_x(mfn) + i2" would be shorter and
> hence imo preferable, especially in printk() and alike invocations.
The goal of using typesafe is to make the code safer not try to
open-code everything because it might be shorter to write.
>
> I would also prefer if you left %#lx alone, with the 2nd best
> option being to also use PRI_gfn alongside PRI_mfn. Primarily
> I'd like to avoid having a mixture.
The two options would be wrong:
* gfn is an unsigned long and not gfn_t, so using PRI_gfn would be
incorrect
* mfn is now an mfn_t so using %lx would be incorrect
So the format string used in the patch is correct based on the types
used. This...
>
> Same (for both) at least one more time further down.
... would likely be applicable for all the other uses.
>> @@ -974,7 +974,7 @@ guest_physmap_add_entry(struct domain *d, gfn_t gfn, mfn_t mfn,
>> P2M_DEBUG("old gfn=%#lx -> mfn %#lx\n",
>> gfn_x(ogfn) , mfn_x(omfn));
>> if ( mfn_eq(omfn, mfn_add(mfn, i)) )
>> - p2m_remove_page(p2m, gfn_x(ogfn), mfn_x(mfn_add(mfn, i)),
>> + p2m_remove_page(p2m, gfn_x(ogfn), mfn_add(mfn, i),
>> 0);
>
> Pull this up then onto the now shorter prior line?
Ok.
>
>> @@ -2843,53 +2843,53 @@ void audit_p2m(struct domain *d,
>> spin_lock(&d->page_alloc_lock);
>> page_list_for_each ( page, &d->page_list )
>> {
>> - mfn = mfn_x(page_to_mfn(page));
>> + mfn = page_to_mfn(page);
>>
>> - P2M_PRINTK("auditing guest page, mfn=%#lx\n", mfn);
>> + P2M_PRINTK("auditing guest page, mfn=%"PRI_mfn"\n", mfn_x(mfn));
>>
>> od = page_get_owner(page);
>>
>> if ( od != d )
>> {
>> - P2M_PRINTK("mfn %"PRI_mfn" owner %pd != %pd\n", mfn, od, d);
>> + P2M_PRINTK("mfn %"PRI_mfn" owner %pd != %pd\n", mfn_x(mfn), od, d);
>> continue;
>> }
>>
>> - gfn = get_gpfn_from_mfn(mfn);
>> + gfn = get_pfn_from_mfn(mfn);
>> if ( gfn == INVALID_M2P_ENTRY )
>> {
>> orphans_count++;
>> - P2M_PRINTK("orphaned guest page: mfn=%#lx has invalid gfn\n",
>> - mfn);
>> + P2M_PRINTK("orphaned guest page: mfn=%"PRI_mfn" has invalid gfn\n",
>> + mfn_x(mfn));
>> continue;
>> }
>>
>> if ( SHARED_M2P(gfn) )
>> {
>> - P2M_PRINTK("shared mfn (%lx) on domain page list!\n",
>> - mfn);
>> + P2M_PRINTK("shared mfn (%"PRI_mfn") on domain page list!\n",
>> + mfn_x(mfn));
>> continue;
>> }
>>
>> p2mfn = get_gfn_type_access(p2m, gfn, &type, &p2ma, 0, NULL);
>> - if ( mfn_x(p2mfn) != mfn )
>> + if ( !mfn_eq(p2mfn, mfn) )
>> {
>> mpbad++;
>> - P2M_PRINTK("map mismatch mfn %#lx -> gfn %#lx -> mfn %#lx"
>> + P2M_PRINTK("map mismatch mfn %"PRI_mfn" -> gfn %#lx -> mfn %"PRI_mfn""
>> " (-> gfn %#lx)\n",
>> - mfn, gfn, mfn_x(p2mfn),
>> + mfn_x(mfn), gfn, mfn_x(p2mfn),
>> (mfn_valid(p2mfn)
>> - ? get_gpfn_from_mfn(mfn_x(p2mfn))
>> + ? get_pfn_from_mfn(p2mfn)
>> : -1u));
>
> I realize this is an entirely unrelated change, but the -1u here
> is standing out too much to not mention it: Could I talk you into
> making this gfn_x(INVALID_GFN) at this occasion?
Hmmm, I am not sure why I missed this one. I will use gfn_x(INVALID_GFN).
>
>> --- a/xen/include/asm-x86/mm.h
>> +++ b/xen/include/asm-x86/mm.h
>> @@ -500,9 +500,10 @@ extern paddr_t mem_hotplug;
>> */
>> extern bool machine_to_phys_mapping_valid;
>>
>> -static inline void set_gpfn_from_mfn(unsigned long mfn, unsigned long pfn)
>> +static inline void set_pfn_from_mfn(mfn_t mfn_, unsigned long pfn)
>> {
>> - const struct domain *d = page_get_owner(mfn_to_page(_mfn(mfn)));
>> + const unsigned long mfn = mfn_x(mfn_);
>
> I think it would be better overall if the parameter was named
> "mfn" and there was no local variable altogether. This would
> bring things in line with ...
You asked for this approach on the previous version [1]:
"Btw, the cheaper (in terms of code churn) change here would seem to
be to name the function parameter mfn_, and the local variable mfn.
That'll also reduce the number of uses of the unfortunate trailing-
underscore-name."
So can you pick a side and stick with it?
>
>> @@ -515,11 +516,14 @@ static inline void set_gpfn_from_mfn(unsigned long mfn, unsigned long pfn)
>>
>> extern struct rangeset *mmio_ro_ranges;
>>
>> -#define get_gpfn_from_mfn(mfn) (machine_to_phys_mapping[(mfn)])
>> +static inline unsigned long get_pfn_from_mfn(mfn_t mfn)
>> +{
>> + return machine_to_phys_mapping[mfn_x(mfn)];
>> +}
>
> ... this.
>
> Jan
>
Cheers,
[1] <5CF7A1090200007800235782@prv1-mh.provo.novell.com>
--
Julien Grall
next prev parent reply other threads:[~2020-03-28 11:15 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-22 16:14 [Xen-devel] [PATCH 00/17] Bunch of typesafe conversion julien
2020-03-22 16:14 ` [Xen-devel] [PATCH 01/17] xen/x86: Introduce helpers to generate/convert the CR3 from/to a MFN/GFN julien
2020-03-25 14:46 ` Jan Beulich
2020-03-28 10:14 ` Julien Grall
2020-03-30 7:38 ` Jan Beulich
2020-04-16 11:50 ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 02/17] xen/x86_64: Convert do_page_walk() to use typesafe MFN julien
2020-03-25 14:51 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 03/17] xen/mm: Move the MM types in a separate header julien
2020-03-25 15:00 ` Jan Beulich
2020-03-25 18:09 ` Julien Grall
2020-03-26 9:02 ` Jan Beulich
2020-03-28 10:15 ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 04/17] xen: Convert virt_to_mfn() and mfn_to_virt() to use typesafe MFN julien
2020-03-25 15:27 ` Jan Beulich
2020-03-25 18:21 ` Julien Grall
2020-03-26 9:09 ` Jan Beulich
2020-03-28 10:33 ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 05/17] xen/x86: Remove the non-typesafe version of pagetable_* helpers julien
2020-03-26 15:39 ` Jan Beulich
2020-03-28 10:52 ` Julien Grall
2020-03-30 7:52 ` Jan Beulich
2020-04-18 10:23 ` Julien Grall
2020-04-20 9:16 ` Jan Beulich
2020-04-20 10:10 ` Julien Grall
2020-04-20 12:14 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 06/17] xen/x86: mm: Fix the comment on top put_page_from_l2e() to use 'mfn' julien
2020-03-26 15:51 ` Jan Beulich
2020-04-18 10:54 ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 07/17] xen/x86: traps: Convert __page_fault_type() to use typesafe MFN julien
2020-03-26 15:54 ` Jan Beulich
2020-04-18 11:01 ` Julien Grall
2020-04-18 11:43 ` Julien Grall
2020-04-20 9:19 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 08/17] xen/x86: traps: Convert show_page_walk() " julien
2020-03-22 16:14 ` [Xen-devel] [PATCH 09/17] xen/x86: Reduce the number of use of l*e_{from, get}_pfn() julien
2020-03-27 10:52 ` Jan Beulich
2020-03-28 10:53 ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 10/17] xen/x86: pv: Use maddr_to_mfn(...) instead of the open-coding version julien
2020-03-27 11:34 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 11/17] xen/x86: nested_ept: Fix typo in the message in nept_translate_l2ga() julien
2020-03-27 11:35 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 12/17] xen/x86: p2m: Remove duplicate error message in p2m_pt_audit_p2m() julien
2020-03-27 11:35 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 13/17] xen/x86: p2m: Reflow P2M_PRINTK()s " julien
2020-03-27 11:36 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 14/17] xen/x86: mm: Re-implement set_gpfn_from_mfn() as a static inline function julien
2020-03-27 12:44 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 15/17] xen/x86: p2m: Rework printk format in audit_p2m() julien
2020-03-27 12:45 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 16/17] xen/mm: Convert {s, g}et_gpfn_from_mfn() to use typesafe MFN julien
2020-03-23 12:11 ` Hongyan Xia
2020-03-23 12:26 ` Julien Grall
2020-03-27 13:15 ` Jan Beulich
2020-03-28 11:14 ` Julien Grall [this message]
2020-03-30 8:10 ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 17/17] xen: Switch parameter in get_page_from_gfn to use typesafe gfn julien
2020-03-23 8:37 ` Paul Durrant
2020-03-23 10:26 ` Julien Grall
2020-03-27 13:50 ` Jan Beulich
2020-03-27 13:59 ` Julien Grall
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