Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942235AbcJSO0L (ORCPT ); Wed, 19 Oct 2016 10:26:11 -0400 Received: from mail-vk0-f41.google.com ([209.85.213.41]:35543 "EHLO mail-vk0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942309AbcJSO0D (ORCPT ); Wed, 19 Oct 2016 10:26:03 -0400 Date: Wed, 19 Oct 2016 12:32:00 +0100 From: Matt Fleming To: Alex Thorlton Cc: linux-kernel@vger.kernel.org, Mike Travis , Russ Anderson , Dimitri Sivanich , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Masahiro Yamada , x86@kernel.org, Ard Biesheuvel Subject: Re: [PATCH] x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates Message-ID: <20161019113200.GE31476@codeblueprint.co.uk> References: <1476794858-200667-1-git-send-email-athorlton@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1476794858-200667-1-git-send-email-athorlton@sgi.com> User-Agent: Mutt/1.5.24+41 (02bc14ed1569) (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2836 Lines: 67 On Tue, 18 Oct, at 07:47:38AM, Alex Thorlton wrote: > Some time ago, we brought our UV BIOS callback code up to speed with the > new EFI memory mapping scheme, in commit: > > d1be84a232e3 ("x86/uv: Update uv_bios_call() to use efi_call_virt_pointer()") > > By leveraging some changes that I made to a few of the EFI runtime > callback mechanisms, in commit: > > 80e75596079f ("efi: Convert efi_call_virt() to efi_call_virt_pointer()") > > This got everything running smoothly on UV, with the new EFI mapping > code. However, this left one, small loose end, in that EFI_OLD_MEMMAP > (a.k.a. efi=old_map) will no longer work on UV, on kernels that include > the aforementioned changes. > > At the time this was not a major issue (in fact, it still really isn't), > but there's no reason that EFI_OLD_MEMMAP *shouldn't* work on our > systems. This commit adds a check into uv_bios_call, to see if we have > the EFI_OLD_MEMMAP bit set in efi.flags. If it is set, we fall back to > using our old callback method, which uses efi_call directly on the __va > of our function pointer. > > Signed-off-by: Alex Thorlton > Cc: Mike Travis > Cc: Russ Anderson > Cc: Dimitri Sivanich > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Matt Fleming > Cc: Masahiro Yamada > Cc: x86@kernel.org > --- > arch/x86/platform/uv/bios_uv.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c > index b4d5e95..12b6e52 100644 > --- a/arch/x86/platform/uv/bios_uv.c > +++ b/arch/x86/platform/uv/bios_uv.c > @@ -40,7 +40,15 @@ s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5) > */ > return BIOS_STATUS_UNIMPLEMENTED; > > - ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5); > + /* > + * If EFI_OLD_MEMMAP is set, we need to fall back to using our old EFI > + * callback method, which uses efi_call directly, with the kernel page tables. > + */ > + if (!test_bit(EFI_OLD_MEMMAP, &efi.flags)) > + ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5); > + else > + ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5); > + > return ret; > } > EXPORT_SYMBOL_GPL(uv_bios_call); Could you please invert the conditional? I had to read it 3 times to make sure it was correct given the comment that precedes it. E.g. this is preferable, if (efi_enabled(EFI_OLD_MEMMAP)) ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5); else ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);