From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v7.1 07/24] x86/mm: Introduce modify_xen_mappings()
Date: Mon, 11 Apr 2016 18:33:10 +0100 [thread overview]
Message-ID: <570BDFD6.5000603@citrix.com> (raw)
In-Reply-To: <570BEA7E02000078000E642A@prv-mh.provo.novell.com>
On 11/04/16 18:18, Jan Beulich wrote:
>>>> On 11.04.16 at 16:04, <andrew.cooper3@citrix.com> wrote:
>> @@ -5964,6 +5976,10 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
>> unsigned int i;
>> unsigned long v = s;
>>
>> + /* Set of valid PTE bits which may be altered. */
>> +#define FLAGS_MASK (_PAGE_NX|_PAGE_RW|_PAGE_PRESENT)
>> + nf &= FLAGS_MASK;
> While we don't need it right away, I think including _PAGE_USER
> here would be quite fine.
I considered that. Until we have a valid use for doing so, I chose not
to give people the opportunity to shoot themselves in the foot.
>
>> @@ -6055,13 +6085,23 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
>> }
>> else
>> {
>> + l1_pgentry_t nl1e;
>> +
>> /* Ordinary 4kB mapping. */
>> pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(v);
>> - l1e_write_atomic(pl1e, l1e_empty());
>> +
>> + nl1e = !(nf & _PAGE_PRESENT) ? l1e_empty()
>> + : l1e_from_pfn(l1e_get_pfn(*pl1e),
>> + (l1e_get_flags(*pl1e) & ~FLAGS_MASK) | nf);
>> +
>> + l1e_write_atomic(pl1e, nl1e);
> Up in the 2M and 1G super page modification logic you check we're
> not creating a new mapping - why not here, too?
Good point. I will add one. (I did have one orignally, and it got lost
through a couple of refactors.)
>
>> v += PAGE_SIZE;
>>
>> - /* If we are done with the L2E, check if it is now empty. */
>> - if ( (v != e) && (l1_table_offset(v) != 0) )
>> + /*
>> + * If we are destroying mappings and done with the L2E, check if
>> + * it is now empty.
>> + */
>> + if ( (nf & _PAGE_PRESENT) && (v != e) && (l1_table_offset(v) != 0) )
>> continue;
> Doesn't this need to be
>
> if ( (nf & _PAGE_PRESENT) || ((v != e) && l1_table_offset(v)) )
>
> ?
It should. On further consideration, I am also going to invert the
sense of the comment, to match the code.
~Andrew
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next prev parent reply other threads:[~2016-04-11 17:33 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-10 21:14 [PATCH v7] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 01/24] xsplice: Design document Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 02/24] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 03/24] libxc: Implementation of XEN_XSPLICE_op in libxc Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 04/24] xen-xsplice: Tool to manipulate xsplice payloads Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 05/24] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables lookup Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 06/24] arm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type Konrad Rzeszutek Wilk
2016-04-11 9:39 ` Andrew Cooper
2016-04-11 13:29 ` Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 07/24] x86/mm: Introduce modify_xen_mappings() Konrad Rzeszutek Wilk
2016-04-11 12:51 ` George Dunlap
2016-04-11 13:00 ` Andrew Cooper
2016-04-11 14:04 ` [PATCH v7.1 " Andrew Cooper
2016-04-11 15:21 ` George Dunlap
2016-04-11 17:18 ` Jan Beulich
2016-04-11 17:33 ` Andrew Cooper [this message]
2016-04-11 17:46 ` [PATCH v7.2 " Andrew Cooper
2016-04-11 17:54 ` Jan Beulich
2016-04-12 9:08 ` Andrew Cooper
2016-04-10 21:14 ` [PATCH v7 08/24] xsplice: Add helper elf routines Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 09/24] xsplice: Implement payload loading Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 10/24] xsplice: Implement support for applying/reverting/replacing patches Konrad Rzeszutek Wilk
2016-04-11 10:14 ` Andrew Cooper
2016-04-11 13:29 ` Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 11/24] x86/xen_hello_world.xsplice: Test payload for patching 'xen_extra_version' Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 12/24] xsplice, symbols: Implement symbol name resolution on address Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 13/24] x86, xsplice: Print payload's symbol name and payload name in backtraces Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 14/24] xsplice: Add support for bug frames Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 15/24] xsplice: Add support for exception tables Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 16/24] xsplice: Add support for alternatives Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 17/24] build_id: Provide ld-embedded build-ids Konrad Rzeszutek Wilk
2016-04-11 12:17 ` Andrew Cooper
2016-04-11 13:31 ` Konrad Rzeszutek Wilk
2016-04-11 13:35 ` Andrew Cooper
2016-04-10 21:14 ` [PATCH v7 18/24] HYPERCALL_version_op: Add VERSION_build_id to retrieve build-id Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 19/24] libxl: info: Display build_id of the hypervisor using XEN_VERSION_build_id Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 20/24] xsplice: Print build_id in keyhandler and on bootup Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 21/24] xsplice: Stacking build-id dependency checking Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 22/24] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 23/24] xsplice: Prevent duplicate payloads from being loaded Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 24/24] MAINTAINERS/xsplice: Add myself and Ross as the maintainers Konrad Rzeszutek Wilk
2016-04-11 14:32 ` [PATCH v7] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-04-11 15:43 ` Konrad Rzeszutek Wilk
2016-04-12 8:10 ` Ross Lagerwall
2016-04-12 20:59 ` Konrad Rzeszutek Wilk
2016-04-12 20:59 ` [PATCH v7 25/24] symbols/xsplice: Implement fast symbol names -> virtual addresses lookup Konrad Rzeszutek Wilk
2016-04-13 2:03 ` Konrad Rzeszutek Wilk
2016-04-13 2:17 ` Konrad Rzeszutek Wilk
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