From: Tom Lendacky <thomas.lendacky@amd.com>
To: Rik van Riel <riel@surriel.com>, Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
peterz@infradead.org, dave.hansen@linux.intel.com,
zhengqi.arch@bytedance.com, nadav.amit@gmail.com,
kernel-team@meta.com, linux-mm@kvack.org,
akpm@linux-foundation.org, jackmanb@google.com, jannh@google.com,
mhklinux@outlook.com, andrew.cooper3@citrix.com,
Manali.Shukla@amd.com, mingo@kernel.org
Subject: Re: [PATCH v13 06/14] x86/mm: use broadcast TLB flushing for page reclaim TLB flushing
Date: Wed, 26 Feb 2025 12:12:23 -0600 [thread overview]
Message-ID: <2731f073-d529-7870-6d25-ebd2e44cd10c@amd.com> (raw)
In-Reply-To: <9086371cfe69760780d67ec279f69e91f65086a7.camel@surriel.com>
On 2/26/25 11:46, Rik van Riel wrote:
> On Wed, 2025-02-26 at 11:36 -0600, Tom Lendacky wrote:
>>
>> Right, but the ASID valid bit is not set, so the flushing may match
>> more
>> than just host/hypervisor TLB entries.
>>
> Good point, when using SVM these flushes could result
> in flushing more TLB entries than we really want.
>
> On the flip side, when SVM is not initialized, the
> invlpgb instruction will fail with a general protection
> fault if we have anything at all in the ASID field.
>
> I don't know whether setting the ASID valid bit in
> rAX will cause a system to crash when SVM is not
> enabled or initialized.
As long as you keep the ASID value in EDX[15:0] as 0, then you won't
#GP. ASID 0 is the host/hypervisor. An ASID > 0 belongs to a guest.
Thanks,
Tom
>
next prev parent reply other threads:[~2025-02-26 18:12 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-23 19:48 [PATCH v13 00/14] AMD broadcast TLB invalidation Rik van Riel
2025-02-23 19:48 ` [PATCH v13 01/14] x86/mm: consolidate full flush threshold decision Rik van Riel
2025-02-24 11:48 ` Borislav Petkov
2025-02-23 19:48 ` [PATCH v13 02/14] x86/mm: get INVLPGB count max from CPUID Rik van Riel
2025-02-24 12:00 ` Borislav Petkov
2025-02-23 19:48 ` [PATCH v13 03/14] x86/mm: add INVLPGB support code Rik van Riel
2025-02-24 12:14 ` Borislav Petkov
2025-02-23 19:48 ` [PATCH v13 04/14] x86/mm: use INVLPGB for kernel TLB flushes Rik van Riel
2025-02-24 12:31 ` Borislav Petkov
2025-02-24 12:44 ` Nadav Amit
2025-02-23 19:48 ` [PATCH v13 05/14] x86/mm: use INVLPGB in flush_tlb_all Rik van Riel
2025-02-24 12:46 ` Borislav Petkov
2025-02-23 19:48 ` [PATCH v13 06/14] x86/mm: use broadcast TLB flushing for page reclaim TLB flushing Rik van Riel
2025-02-24 13:27 ` Borislav Petkov
2025-02-25 19:17 ` Rik van Riel
2025-02-25 20:38 ` Borislav Petkov
2025-02-25 21:03 ` Borislav Petkov
2025-02-25 22:03 ` Rik van Riel
2025-02-26 17:00 ` Tom Lendacky
2025-02-26 17:02 ` Rik van Riel
2025-02-26 17:36 ` Tom Lendacky
2025-02-26 17:46 ` Rik van Riel
2025-02-26 18:12 ` Tom Lendacky [this message]
2025-02-26 22:01 ` Rik van Riel
2025-02-28 1:13 ` Rik van Riel
2025-02-28 15:02 ` Tom Lendacky
2025-02-28 15:57 ` Sean Christopherson
2025-02-28 20:42 ` Tom Lendacky
2025-02-23 19:48 ` [PATCH v13 07/14] x86/mm: global ASID allocation helper functions Rik van Riel
2025-02-24 14:16 ` Borislav Petkov
2025-02-25 20:22 ` Rik van Riel
2025-02-23 19:48 ` [PATCH v13 08/14] x86/mm: global ASID context switch & TLB flush handling Rik van Riel
2025-02-23 23:08 ` kernel test robot
2025-02-24 1:26 ` Rik van Riel
2025-02-24 2:01 ` Rik van Riel
2025-02-24 18:41 ` kernel test robot
2025-02-23 19:48 ` [PATCH v13 09/14] x86/mm: global ASID process exit helpers Rik van Riel
2025-02-23 19:49 ` [PATCH v13 10/14] x86/mm: enable broadcast TLB invalidation for multi-threaded processes Rik van Riel
2025-02-23 19:49 ` [PATCH v13 11/14] x86/mm: do targeted broadcast flushing from tlbbatch code Rik van Riel
2025-02-23 19:49 ` [PATCH v13 12/14] x86/mm: enable AMD translation cache extensions Rik van Riel
2025-02-23 19:49 ` [PATCH v13 13/14] x86/mm: only invalidate final translations with INVLPGB Rik van Riel
2025-02-23 19:49 ` [PATCH v13 14/14] x86/mm: add noinvlpgb commandline option Rik van Riel
2025-02-23 21:29 ` Borislav Petkov
2025-02-24 0:34 ` Rik van Riel
2025-02-24 6:29 ` Borislav Petkov
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