Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751447AbdINIIW (ORCPT ); Thu, 14 Sep 2017 04:08:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36748 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168AbdINIIV (ORCPT ); Thu, 14 Sep 2017 04:08:21 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com EB9FA806A1 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=bhe@redhat.com Date: Thu, 14 Sep 2017 16:08:14 +0800 From: Baoquan He To: Dave Young Cc: linux-kernel@vger.kernel.org, x86@kernel.org, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, thgarnie@google.com, keescook@chromium.org, akpm@linux-foundation.org, yamada.masahiro@socionext.com, rja@hpe.com, frank.ramsay@hpe.com Subject: Re: [PATCH v2 RESEND 1/2] x86/UV: Introduce a helper function to check UV system at earlier stage Message-ID: <20170914080814.GO12824@x1> References: <1504770150-25456-1-git-send-email-bhe@redhat.com> <1504770150-25456-2-git-send-email-bhe@redhat.com> <20170914072952.GN12824@x1> <20170914074901.GA5182@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170914074901.GA5182@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.7.0 (2016-08-17) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 14 Sep 2017 08:08:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2488 Lines: 72 On 09/14/17 at 03:49pm, Dave Young wrote: > > > diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h > > > index b5a32231abd8..93d7ad8763ba 100644 > > > --- a/arch/x86/include/asm/uv/uv.h > > > +++ b/arch/x86/include/asm/uv/uv.h > > > @@ -18,6 +18,11 @@ extern void uv_nmi_init(void); > > > extern void uv_system_init(void); > > > extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask, > > > const struct flush_tlb_info *info); > > > +#include > > > +static inline int is_early_uv_system(void) > > > +{ > > > + return !((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || !efi.uv_systab); > > > +} > Thanks for looking into this, Dave! > > Sorry for jumping in late, I have two questions about the patch: > > 1) For efi tables, the only invalid value is EFI_INVALID_TABLE_ADDR, and > efi struct is initialized as EFI_INVALID_TABLE_ADDR by default so no > need to check "|| !efi.uv_systab". Do we have any UV firmware specific > assumption that "0" is also possible to be assigned? Hmm, in uv_bios_init() it also checks the !efi.uv_systab case. And EFI_INVALID_TABLE_ADDR checking is earlier, it won't affect the result if it's EFI_INVALID_TABLE_ADDR. And !efi.uv_systab can make it safer since it doesn't work either if efi.uv_systab is 0. Mainly it's not harmful. Mike, what's your thought? Should I only check the (efi.uv_systab == EFI_INVALID_TABLE_ADDR) case? > > 2) It seems adding this function in uv.h for separating this for uv > system only purpose. But I feel it is better to put it in efi.h instead. At the beginning I put it in efi.c, later Mike suggested putting it in asm/uv/uv.h. You can also find the discussion in below link. https://patchwork.kernel.org/patch/9732787/ Thanks Baoquan > > uv_systab is already a member of struct efi, it is in efi.h so it is > natural to check the table exist or not. Then just include efi.h in > kaslr.c and use the function. > > something like drivers/firmware/efi/esrt.c: esrt_table_exists() > > Anyway I have no strong opinon, it looks more natural to me though. > > > > > > > #else /* X86_UV */ > > > > > > @@ -30,6 +35,7 @@ static inline const struct cpumask * > > > uv_flush_tlb_others(const struct cpumask *cpumask, > > > const struct flush_tlb_info *info) > > > { return cpumask; } > > > +static inline int is_early_uv_system(void) { return 0; } > > > > > > #endif /* X86_UV */ > > > > > > -- > > > 2.5.5 > > > > > Thanks > Dave