Xen project Mailing List

Re: [PATCH v2] SUPPORT.md: extend security support for x86 hosts to 12 TiB of memory

Date: Wed, 25 May 2022 13:11:52 +0200

Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none

Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=NhJ/hkYyGjiLhb/bgpOLzeT3CNP2lxqvZcaKsWBYCmQ=; b=nuxb6ds3DT8XcdZ5mxMsORRoTrXFLnD3GTFG2v9TElaWeMOeYD6wYI2ZVWFd3stGKfb3TAZGrglMMzrpVNnunH9QZnQssc2Wnd3CYM1U/PLivSGynlDN33GX/a+G3Bwk9gu3wv8pRl8uo3lHXuSkG6K1JRCQ3YFlbYx3psqVxeY0gIsw0Aqd3eeQoak3FX6VHqwwkDoLhAVYH8XGVYd8zIV7m6fUgeckZvlv2sj+6Nu54E/pP+oZplmBIXaOcJWOgAh9sGtduOS8Zg74LOvFMm+QimyRGy6CuTjsgDVa6KaB0Yzl6bQEmv6YzaHNstkKoOCTeNJBjG6FgBq5yoaeIQ==

Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Msw8hEt/TckhbKF2BmBhCZtQKmyhbVQQB5dYEheCk845rziJ0e6gUXr/GlBEE3z3c4rupRmFIz3xkEGBMR02/+2ClANhHacGj+HiKbMWRzuej2tWzMw2m3Q3OGJfeAZeyWFHz4tc+Y1OdECCfblVvfwgrJx7rGnuVznZNJT0450IDyhH+wE0pP0HdkN5Hnp2e9JSoPkmUu4AoL5OS7NDNgRSpVCwzyEEL1TrMm5O/RLV2C8fSBZWSWiesrehkzJKWnGpaHxIdT1zE2AuT/lSLo2Vyyr20WlEp8y+hat1qMy34cKKWoUcuoQEIW0tWtTbDpUAiGciDoWIkmJeiUmqFQ==

Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com;

Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>

Delivery-date: Wed, 25 May 2022 11:12:24 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 25.05.2022 12:58, Julien Grall wrote: > On 25/05/2022 10:21, Jan Beulich wrote: >> --- a/SUPPORT.md >> +++ b/SUPPORT.md >> @@ -50,7 +50,7 @@ For the Cortex A57 r0p0 - r1p1, see Erra >> >> ### Physical Memory >> >> - Status, x86: Supported up to 8 TiB. Hosts with more memory are >> supported, but not security supported. >> + Status, x86: Supported up to 12 TiB. Hosts with more memory are >> supported, but not security supported. >> Status, Arm32: Supported up to 12 GiB >> Status, Arm64: Supported up to 2 TiB >> >> @@ -121,6 +121,17 @@ ARM only has one guest type at the momen >> >> Status: Supported >> >> +## Guest Limits >> + >> +### Memory >> + >> + Status, x86: Supported up to 8 TiB >> + Status, Arm64: Supported up to 1 TiB >> + Status, Arm32: Supported up to 32 GiB > > IIRC, the max the architecture would allow us is 16 Gib. Here we are > limited with how much physical memory is supported by Xen. So this wants > to be 12 GiB. Hmm, while I don't know where I took the 32 from, it was you who suggested (in reply to v1) I put 16 here. Though yes, with the host limit now set to just 12, putting more here would be odd. I didn't cross check the numbers, I'll admit. >> + >> +Guests with more memory, but less than 16 TiB, are supported, >> +but not security supported. > > On Arm32, we definitely can't support up to 16 TiB. On Arm64, we would > need some work to support it. So I would move this sentence in the > "Status, x86" section. Sure, I can do that. Would have been nice if you had said so right on v1. As to Arm64 though - the host limit is 2 TiB. Going beyond that being impossible (without becoming at least unsupported), is the uniform upper bound of 16 TiB really a problem here (IOW do guests really only function up to 1 TiB)? For Arm32 it would be even less of an issue, as hosts with more than 12 GiB are unsupported. (I'm trying to avoid moving the line up not the least because it'll be even more of a line length violation than what was necessary to accept for the host limits.) Jan

©2013 Xen Project, A Linux Foundation Collaborative Project. All Rights Reserved.
Linux Foundation is a registered trademark of The Linux Foundation.
Xen Project is a trademark of The Linux Foundation.