Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966454AbaFRMcF (ORCPT ); Wed, 18 Jun 2014 08:32:05 -0400 Received: from smtp.citrix.com ([66.165.176.89]:7176 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966306AbaFRMcE (ORCPT ); Wed, 18 Jun 2014 08:32:04 -0400 X-IronPort-AV: E=Sophos;i="5.01,499,1400025600"; d="scan'208";a="144865924" Message-ID: <53A186BC.6040107@citrix.com> Date: Wed, 18 Jun 2014 13:31:56 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: Matt Fleming , Daniel Kiper CC: , , , , , , , , , , , , , , , , , Mark Salter Subject: Re: [PATCH v5 1/7] efi: Use early_mem*() instead of early_io*() References: <1402678823-24589-1-git-send-email-daniel.kiper@oracle.com> <1402678823-24589-2-git-send-email-daniel.kiper@oracle.com> <20140618121709.GF24049@console-pimps.org> In-Reply-To: <20140618121709.GF24049@console-pimps.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.76] X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/06/14 13:17, Matt Fleming wrote: > (Pulling in Mark Salter for early_ioremap() knowledge) > > On Fri, 13 Jun, at 07:00:17PM, Daniel Kiper wrote: >> Use early_mem*() instead of early_io*() because all mapped EFI regions >> are true RAM not I/O regions. Additionally, I/O family calls do not work >> correctly under Xen in our case. AIUI, early_io*() maps/unmaps real machine >> addresses. However, all artificial EFI structures created under Xen live >> in dom0 memory and should be mapped/unmapped using early_mem*() family >> calls which map domain memory. >> >> Signed-off-by: Daniel Kiper >> --- >> arch/x86/platform/efi/efi.c | 42 +++++++++++++++++++++--------------------- >> drivers/firmware/efi/efi.c | 4 ++-- >> 2 files changed, 23 insertions(+), 23 deletions(-) >> >> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c >> index 87fc96b..dd1e351 100644 >> --- a/arch/x86/platform/efi/efi.c >> +++ b/arch/x86/platform/efi/efi.c >> @@ -427,7 +427,7 @@ void __init efi_unmap_memmap(void) >> { >> clear_bit(EFI_MEMMAP, &efi.flags); >> if (memmap.map) { >> - early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size); >> + early_memunmap(memmap.map, memmap.nr_map * memmap.desc_size); >> memmap.map = NULL; >> } >> } >> @@ -467,12 +467,12 @@ static int __init efi_systab_init(void *phys) >> if (!data) >> return -ENOMEM; >> } >> - systab64 = early_ioremap((unsigned long)phys, >> - sizeof(*systab64)); >> + systab64 = early_memremap((unsigned long)phys, >> + sizeof(*systab64)); > > Please don't misalign the arguments :-( This makes the diff harder to > read when all you're doing is changing the function call. You're > indentation isn't an improvement. > > As Matthew pointed out we may also need to access EFI mapped flash > devices. > > Now, the only difference between early_memremap() and early_ioremap(), > at least on x86, is PAGE_KERNEL vs. PAGE_KERNEL_IO, where PAGE_KERNEL_IO > has the additional _PAGE_BIT_IOMAP bit set in the pte. But that's a > software bit for x86. _PAGE_BIT_IOMAP is supposed to be going away... > So, even though this change should be harmless, it's not clear to me why > this change is needed. You say "I/O family calls do not work correctly > under Xen in our case", but could you provide some more explanation as > to why they don't work correctly? _PAGE_BIT_IOMAP causes a Xen PV guest to skip the PFN to MFN conversion when building the PTE. Using it for RAM will attempt to map the wrong machine frame. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/