From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: Re: efi_enabled(EFI_PARAVIRT) use Date: Fri, 29 Apr 2016 16:53:21 +0200 Message-ID: References: <20160429142020.4499e185@canb.auug.org.au> <20160429063936.GA28320@gmail.com> <20160429143931.GG2839@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20160429143931.GG2839@codeblueprint.co.uk> Sender: linux-next-owner@vger.kernel.org To: Matt Fleming Cc: Stefano Stabellini , Ingo Molnar , Stephen Rothwell , "Luis R. Rodriguez" , Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , Stefano Stabellini , Xen Devel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-next@vger.kernel.org, "linux-kernel@vger.kernel.org" , Shannon Zhao , Borislav Petkov List-Id: xen-devel@lists.xenproject.org On 29 April 2016 at 16:39, Matt Fleming wrote: > On Fri, 29 Apr, at 11:34:45AM, Stefano Stabellini wrote: >> On Fri, 29 Apr 2016, Ingo Molnar wrote: >> > Also, it would be nice to have all things EFI in a single tree, the conflicts are >> > going to be painful! There's very little reason not to carry this kind of commit: >> > >> > arch/arm/xen/enlighten.c | 6 +++++ >> > drivers/firmware/efi/arm-runtime.c | 17 +++++++++----- >> > drivers/firmware/efi/efi.c | 45 ++++++++++++++++++++++++++++++++------ >> > 3 files changed, 56 insertions(+), 12 deletions(-) >> > >> > in the EFI tree. >> >> That's true. I'll drop this commit from xentip and let Matt pick it up >> or request changes as he sees fit. > > One small change I think would be sensible to make is to expand > EFI_PARAVIRT into a few more bits to clearly indicate the quirks on > Xen, and in the process, to delete EFI_PARAVIRT. > > That should address Ingo's major concern, and also make it much easier > to rework the code in a piecemeal fashion. > > Could somebody enumerate the things that make Xen (dom0) different on > arm* compared with bare metal EFI boot? The list I made for x86 was, > > 1. Has no EFI memory map > 2. Runtime regions do not need to be mapped > 3. Cannot call SetVirtualAddressMap() > 4. /sys/firmware/efi/fw_vendor is invisible > > The first maps to not setting EFI_MEMMAP, the second to not setting > EFI_RUNTIME. If we add EFI_ALREADY_VIRTUAL and EFI_FW_VENDOR_INVISIBLE > to efi.flags that should cover everything on x86. Does arm* require > anything else? I already proposed when this patch was first under review to make the arm_enable_runtime_services() function bail early without error if the EFI_RUNTIME_SERVICES flag is already set, and the xen code could set that bit as well when it installs its paravirtualized alternatives. I don't remember exactly why that was shot down, though, but I think it is the only reason this code introduces references to EFI_PARAVIRT in the first place.