From: Jan Beulich <jbeulich@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Elias El Yandouzi <eliasely@amazon.com>,
xen-devel@lists.xenproject.org, julien@xen.org,
pdurrant@amazon.com, dwmw@amazon.com,
Hongyan Xia <hongyxia@amazon.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <jgrall@amazon.com>
Subject: Re: [PATCH V3 (resend) 06/19] x86: Add a boot option to enable and disable the direct map
Date: Thu, 16 May 2024 11:24:49 +0200 [thread overview]
Message-ID: <cc7620c8-a458-451e-badb-8e46d2cb9d90@suse.com> (raw)
In-Reply-To: <ZkXPvgRupZw31nGw@macbook>
On 16.05.2024 11:19, Roger Pau Monné wrote:
> On Wed, May 15, 2024 at 03:54:51PM +0200, Jan Beulich wrote:
>> On 14.05.2024 11:20, Roger Pau Monné wrote:
>>> On Mon, May 13, 2024 at 01:40:33PM +0000, Elias El Yandouzi wrote:
>>>> --- a/docs/misc/xen-command-line.pandoc
>>>> +++ b/docs/misc/xen-command-line.pandoc
>>>> @@ -799,6 +799,18 @@ that enabling this option cannot guarantee anything beyond what underlying
>>>> hardware guarantees (with, where available and known to Xen, respective
>>>> tweaks applied).
>>>>
>>>> +### directmap (x86)
>>>> +> `= <boolean>`
>>>> +
>>>> +> Default: `true`
>>>> +
>>>> +Enable or disable the directmap region in Xen.
>>>
>>> Enable or disable fully populating the directmap region in Xen.
>>
>> Elias, would you please take care to address earlier review comments
>> before sending a new version? This and ...
>>
>>>> +
>>>> +By default, Xen creates the directmap region which maps physical memory
>>> ^ all?
>>>> +in that region. Setting this to no will sparsely populate the directmap,
>>>
>>> "Setting this to no" => "Disabling this option will sparsely..."
>>
>> ... this is what I had already asked for in reply to v2, of course with
>> different wording.
>>
>>>> --- a/xen/arch/x86/setup.c
>>>> +++ b/xen/arch/x86/setup.c
>>>> @@ -1517,6 +1517,8 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p)
>>>> if ( highmem_start )
>>>> xenheap_max_mfn(PFN_DOWN(highmem_start - 1));
>>>>
>>>> + printk("Booting with directmap %s\n", has_directmap() ? "on" : "off");
>>>
>>> IMO this wants to be printed as part of the speculation mitigations, see
>>> print_details() in spec_ctrl.c
>>
>> And not "on" / "off", but "full" / "sparse" (and word order changed accordingly)
>> perhaps.
>
> I've been thinking about this, and I'm leaning towards calling this
> new mode "ondemand" rather than "sparse". The fact that the direct
> map ends up sparely populated is a consequence of populating it on
> demand, and hence the later would be more descriptive IMO.
>
> (Same for the Kconfig option then ONDEMAND_DIRECTMAP, or some such)
Fine with me, fwiw.
Jan
next prev parent reply other threads:[~2024-05-16 9:25 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-13 13:40 [PATCH V3 (resend) 00/19] Remove the directmap Elias El Yandouzi
2024-05-13 13:40 ` [PATCH V3 (resend) 01/19] x86: Create per-domain mapping of guest_root_pt Elias El Yandouzi
2024-05-14 14:51 ` Jan Beulich
2024-05-15 18:25 ` Elias El Yandouzi
2024-05-16 7:17 ` Jan Beulich
2024-06-13 16:31 ` Elias El Yandouzi
2024-06-14 6:23 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 02/19] x86/pv: Domheap pages should be mapped while relocating initrd Elias El Yandouzi
2024-05-13 15:40 ` Roger Pau Monné
2024-05-13 13:40 ` [PATCH V3 (resend) 03/19] x86/pv: Rewrite how building PV dom0 handles domheap mappings Elias El Yandouzi
2024-05-13 16:49 ` Roger Pau Monné
2024-05-14 14:58 ` Jan Beulich
2024-05-14 15:03 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 04/19] x86: Lift mapcache variable to the arch level Elias El Yandouzi
2024-05-14 8:21 ` Roger Pau Monné
2024-05-15 13:11 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 05/19] x86/mapcache: Initialise the mapcache for the idle domain Elias El Yandouzi
2024-05-14 8:42 ` Roger Pau Monné
2024-05-15 13:44 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 06/19] x86: Add a boot option to enable and disable the direct map Elias El Yandouzi
2024-05-14 9:20 ` Roger Pau Monné
2024-05-14 10:20 ` Roger Pau Monné
2024-05-15 13:54 ` Jan Beulich
2024-05-16 9:19 ` Roger Pau Monné
2024-05-16 9:24 ` Jan Beulich [this message]
2024-05-15 13:59 ` Jan Beulich
2024-05-15 16:02 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 07/19] xen/x86: Add support for the PMAP Elias El Yandouzi
2024-05-14 9:40 ` Roger Pau Monné
2024-05-14 9:43 ` Jan Beulich
2024-05-14 10:22 ` Roger Pau Monné
2024-05-14 10:26 ` Jan Beulich
2024-05-14 11:51 ` Roger Pau Monné
2024-05-14 12:33 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 08/19] xen/x86: Add build assertion for fixmap entries Elias El Yandouzi
2024-05-14 9:42 ` Roger Pau Monné
2024-05-14 9:45 ` Jan Beulich
2024-05-15 14:03 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 09/19] x86/domain_page: Remove the fast paths when mfn is not in the directmap Elias El Yandouzi
2024-05-14 11:48 ` Roger Pau Monné
2024-05-15 14:21 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 10/19] xen/page_alloc: Add a path for xenheap when there is no direct map Elias El Yandouzi
2024-05-14 13:07 ` Roger Pau Monné
2024-05-15 15:13 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 11/19] x86/setup: Leave early boot slightly earlier Elias El Yandouzi
2024-05-14 14:11 ` Roger Pau Monné
2024-05-15 15:22 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 12/19] x86/setup: vmap heap nodes when they are outside the direct map Elias El Yandouzi
2024-05-14 15:02 ` Roger Pau Monné
2024-05-15 15:28 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 13/19] x86/setup: Do not create valid mappings when directmap=no Elias El Yandouzi
2024-05-14 15:39 ` Roger Pau Monné
2024-05-15 15:50 ` Jan Beulich
2024-05-15 15:59 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 14/19] Rename mfn_to_virt() calls Elias El Yandouzi
2024-05-14 15:45 ` Roger Pau Monné
2024-05-14 16:22 ` Jan Beulich
2024-05-15 9:38 ` Roger Pau Monné
2024-05-15 9:42 ` Jan Beulich
2024-05-16 8:57 ` Jan Beulich
2024-05-13 13:40 ` [PATCH V3 (resend) 15/19] Rename maddr_to_virt() calls Elias El Yandouzi
2024-05-13 13:40 ` [PATCH V3 (resend) 16/19] xen/arm32: mm: Rename 'first' to 'root' in init_secondary_pagetables() Elias El Yandouzi
2024-05-13 13:40 ` [PATCH V3 (resend) 17/19] xen/arm64: mm: Use per-pCPU page-tables Elias El Yandouzi
2024-05-13 13:40 ` [PATCH V3 (resend) 18/19] xen/arm64: Implement a mapcache for arm64 Elias El Yandouzi
2024-05-13 13:40 ` [PATCH V3 (resend) 19/19] xen/arm64: Allow the admin to enable/disable the directmap Elias El Yandouzi
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