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Shutemov" To: Yosry Ahmed Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Rick Edgecombe , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86/mm: Fix LAM inconsistency during context switch Message-ID: <3a56vovcqy7ju5og76nqlekfruq42i56wmp4oek3jgkffvzjby@q5guufebkpzr> References: <20240312035951.3535980-1-yosryahmed@google.com> <20240312035951.3535980-2-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240312035951.3535980-2-yosryahmed@google.com> X-Rspamd-Queue-Id: 45F8510000B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: gn8xasozzjoag5hzw68eznao66k9uyte X-HE-Tag: 1710246952-391653 X-HE-Meta: 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 Oy+y+GqQ fN4AJAoGw8jTRJG/7uaaeL7GsMh55FVegEtHs0HeTssi7I56NbCajTRXu6TVT3ToGqGZ9lKX+gVH+r88kemJFNDmb8eByuwuzJsCctwgaMVxcuLVbqPjnLKV66zFifJ/1JACQ 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 Tue, Mar 12, 2024 at 03:59:50AM +0000, Yosry Ahmed wrote: > diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c > index 76e91fc68c5f3..748d2b3bdb985 100644 > --- a/arch/x86/kernel/process_64.c > +++ b/arch/x86/kernel/process_64.c > @@ -753,10 +753,12 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) > static void enable_lam_func(void *__mm) > { > struct mm_struct *mm = __mm; > + unsigned long lam = mm_lam_cr3_mask(mm); > + u64 untag_mask = mm_untag_mask(mm); > Maybe push these mm dereferences inside the if block below? I am not sure if compiler can re-order operations past this_cpu_read(). > if (this_cpu_read(cpu_tlbstate.loaded_mm) == mm) { > - write_cr3(__read_cr3() | mm->context.lam_cr3_mask); > - set_tlbstate_lam_mode(mm); > + write_cr3(__read_cr3() | lam); > + cpu_tlbstate_update_lam(lam, untag_mask); > } > } > -- Kiryl Shutsemau / Kirill A. Shutemov