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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: thomas.de_schampheleire@nokia.com
Cc: bp@alien8.de, linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: x86/amd late microcode thread loading slows down boot
Date: Wed, 6 Nov 2024 18:50:12 +0000	[thread overview]
Message-ID: <6449aa6c-43b1-40eb-ab54-48803481d11b@citrix.com> (raw)
In-Reply-To: <ZyulbYuvrkshfsd2@antipodes>

> Hi Borislav, all,
>
> I am encountering varying delays in the boot process

I recognise those symptoms.

https://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=f19a199281a23725beb73bef61eb8964d8e225ce

We found it in Xen in 2019, and were instructed by AMD to insert a TLB
flush immediately after patchloading.

Looking at Linux, there's no such workaround.

It turns out that a side effect of patchloading on some CPUs leaves the
mapping of the blob in the TLB (at whatever granularity) as fully UC. 
When this happens to be a 2M/1G superpage, it causes whole lot of perf
problems in unrelated areas.

I suggest Linux take the same approach.

~Andrew

  reply	other threads:[~2024-11-06 18:50 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-06 17:20 Thomas De Schampheleire
2024-11-06 18:50 ` Andrew Cooper [this message]
2024-11-07 15:30   ` Borislav Petkov
2024-11-07 20:58     ` Thomas De Schampheleire
2024-11-14  9:56       ` Borislav Petkov
2024-11-14 12:03         ` Andrew Cooper
2024-11-15 20:51           ` Borislav Petkov
2024-11-16 19:32             ` Andrew Cooper
2024-11-17 18:23             ` David Laight
2024-11-17 19:52               ` Borislav Petkov
2024-11-18 15:13             ` Thomas De Schampheleire
2024-11-18 15:28               ` Borislav Petkov
2024-11-18 15:58                 ` Thomas De Schampheleire
2024-11-19 10:46                 ` Thomas De Schampheleire
2024-11-19 11:17                   ` Borislav Petkov
2024-11-18 19:16           ` Borislav Petkov
2024-11-14 20:01         ` Thomas De Schampheleire
2024-11-19 11:21 ` [PATCH 1/2] x86/mm: Carve out INVLPG inline asm for use by others Borislav Petkov
2024-11-19 11:21   ` [PATCH 2/2] x86/microcode/AMD: Flush patch buffer mapping after application Borislav Petkov
2024-11-25 11:04 ` [tip: x86/urgent] " tip-bot2 for Borislav Petkov (AMD)
2024-11-25 11:04 ` [tip: x86/urgent] x86/mm: Carve out INVLPG inline asm for use by others tip-bot2 for Borislav Petkov (AMD)

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