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d=hostedemail.com; s=arc-20220608; t=1736802721; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D/7jRmw3lMWINWkKurG0TCVlZsbvFMGawhEfjbGoO3c=; b=q9G3A3gtA3HaXiLICD2Erv0HWIk5gilOIpHLKgajsknrKp4uwN6ndWZxueg1mf4QykA1Pk edAhjFMwKbTIAEkdI97yCluamMz9pwE1ianKb6A2AZ+sXwgVxs4A76TxR1T3sSsR4GnvXc EMwEQBzl0FjLKN4ohMW2jzLI5d3ktCY= Received: from fangorn.home.surriel.com ([10.0.13.7]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1tXRhp-000000008HJ-0Lgp; Mon, 13 Jan 2025 16:10:41 -0500 Message-ID: <7045d1666ac5722820a43fffa7f2e6fb3c2eb485.camel@surriel.com> Subject: Re: [PATCH v4 05/12] x86/mm: add INVLPGB support code From: Rik van Riel To: Tom Lendacky , x86@kernel.org Cc: linux-kernel@vger.kernel.org, bp@alien8.de, 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, jannh@google.com Date: Mon, 13 Jan 2025 16:10:41 -0500 In-Reply-To: <685632f2-44a4-a7fd-063b-1d426896f297@amd.com> References: <20250112155453.1104139-1-riel@surriel.com> <20250112155453.1104139-6-riel@surriel.com> <685632f2-44a4-a7fd-063b-1d426896f297@amd.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.1 (3.54.1-1.fc41) MIME-Version: 1.0 X-Stat-Signature: ig8f9mxfjob9b3se1phrjnwbjd4x7kiw X-Rspam-User: X-Rspamd-Queue-Id: 2FCF540003 X-Rspamd-Server: rspam08 X-HE-Tag: 1736802720-190298 X-HE-Meta: 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 qItIiPq2 aa2E93SmnZsbmmTDzcG9QZAx32KbnM5jwJnK5QtKad4KMUTs1+mr0KqjSYyV1+mCB5EWBL6c6oqH2qOb+zBWORQjhbwNKs0QiCs9ou/v+hSiLP+c9qOLPAj1gLOd0JoGlmQ9NO1NBodWkGGnmo2EXskTMRD7TABJN6YZIZGkbbF7Flk7sgKGPFm8mil86uEc9C0O/w9ZWtCLnlo/lL8GU34mHgrp5hYB2rDITu2mi7/HN0hoIEk3ujibm2OVJM4AEVrtyu1/gyI8sBQFw7zt2EGQXLZWR554i8LA4GQSjE+TzN+pTiaJWaoRCZaa4QTL1hTfLQR7xbaFLeDqscXLNdRfvTA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 2025-01-13 at 08:21 -0600, Tom Lendacky wrote: > On 1/12/25 09:53, Rik van Riel wrote: > >=20 > > +static inline void __invlpgb(unsigned long asid, unsigned long > > pcid, unsigned long addr, > > + =C2=A0=C2=A0=C2=A0 int extra_count, bool pmd_stride, > > unsigned long flags) > > +{ > > + u32 edx =3D (pcid << 16) | asid; > > + u32 ecx =3D (pmd_stride << 31); > > + u64 rax =3D addr | flags; > > + > > + /* Protect against negative numbers. */ > > + extra_count =3D max(extra_count, 0); > > + ecx |=3D extra_count; >=20 > A bad ECX value (ECX[15:0] > invlpgb_count_max) will result in a #GP, > is > that ok? The calling code ensures we do not call this code with more than invlpgb_count_max pages at a time. Given the choice between "a bug in the calling code crashes the kernel" and "a bug in the calling code results in a missed TLB flush", I'm guessing the crash is probably better. --=20 All Rights Reversed.