From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: "Kevin Tian" <kevin.tian@intel.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Wei Liu" <wl@xen.org>, "Paul Durrant" <paul@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>,
"Jun Nakajima" <jun.nakajima@intel.com>,
xen-devel@lists.xenproject.org,
"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: Fri, 27 Mar 2020 13:59:21 +0000 [thread overview]
Message-ID: <e9b4b151-19c2-760a-095f-5a646a025668@xen.org> (raw)
In-Reply-To: <5a5e6da9-ddef-ee4f-fb11-99e3e2b5ef63@suse.com>
Hi Jan,
On 27/03/2020 13:50, Jan Beulich wrote:
> On 22.03.2020 17:14, julien@xen.org wrote:
>> --- 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]),
>
> My earlier comment on this remains - I thing this conversion makes
> the problem this expression has more hidden than with the shift.
> This would better use a gfn_from_cr3() helper (or whatever it'll
> be that it gets named). Same elsewhere in this patch then.
I will have a closer look the *cr3 helpers and reply with some suggestions.
>
>> @@ -2363,7 +2364,7 @@ int hvm_set_cr3(unsigned long value, bool may_defer)
>> {
>> /* Shadow-mode CR3 change. Check PDBR and update refcounts. */
>> HVM_DBG_LOG(DBG_LEVEL_VMMU, "CR3 value = %lx", value);
>> - page = get_page_from_gfn(v->domain, value >> PAGE_SHIFT,
>> + page = get_page_from_gfn(v->domain, cr3_to_gfn(value),
>
> Oh, seeing this I recall Paul did point out the above already.
>
>> @@ -508,7 +508,7 @@ int evtchn_fifo_init_control(struct evtchn_init_control *init_control)
>> {
>> struct domain *d = current->domain;
>> uint32_t vcpu_id;
>> - uint64_t gfn;
>> + gfn_t gfn;
>> uint32_t offset;
>> struct vcpu *v;
>> int rc;
>> @@ -516,7 +516,7 @@ int evtchn_fifo_init_control(struct evtchn_init_control *init_control)
>> init_control->link_bits = EVTCHN_FIFO_LINK_BITS;
>>
>> vcpu_id = init_control->vcpu;
>> - gfn = init_control->control_gfn;
>> + gfn = _gfn(init_control->control_gfn);
>
> There's silent truncation here now for Arm32, afaict. Are we really
> okay with this?
Well, the truncation was already silently happening as we call
get_page_from_gfn() in map_guest_page(). So it is not worse than the
current situation.
Although, there are a slight advantage with the new code as you can more
easily spot potential truncation. Indeed, you could add some type check
in _gfn().
Cheers,
--
Julien Grall
prev parent reply other threads:[~2020-03-27 13:59 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
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 [this message]
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